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2025 Volume 41 Issue 9
2025, 41(9):
Abstract:
2025, 41(9): 100101
doi: 10.1016/j.actphy.2025.100101
Abstract:
2025, 41(9): 100108
doi: 10.1016/j.actphy.2025.100108
Abstract:
The interconversion of N2 and N-containing compounds is central to the natural nitrogen cycle, one of the most important global biogeochemical cycles, which plays a crucial role in sustaining life across all organisms. Nitrogen pollution in surface water bodies, caused by the indiscriminate discharge of industrial and domestic wastewater, has become a global environmental concern. The excessive accumulation of nitrogenous wastes poses a serious threat to human health and disrupts the natural nitrogen cycle. Traditional water purification methods, such as chemical redox processes, physical adsorption, and biological treatments, often face limitations, including high energy consumption, low efficiency, large space requirements, prolonged treatment times, sludge generation, and high operating costs. Emerging electrochemical degradation techniques offer promising solutions for efficiently degrading nitrogenous wastes. These electrochemical technologies demonstrate advantages in cost-effectiveness, environmental friendliness, high efficiency, and broad applicability, while also presenting opportunities to generate added value during the electrodegradation processes. Nitrogen-containing wastes in wastewater can be classified into electrophiles (e.g., nitrate and nitrite) and nucleophiles (e.g., ammonia nitrogen, hydrazine, and urea) according to their redox properties. Based on the different properties of nitrogenous wastes, coupling corresponding electrochemical degradation reactions with tailored electrochemical energy storage and conversion devices provides opportunities for additional energy and value generation. Herein, advanced insights into valorization strategies during the electrodegradation processes of representative nitrogenous wastes in sewage are subtly provided, where the approaches for enhanced value output efficiency are highlighted, including (ⅰ) coupling the electroreduction of electrophilic pollutants with Zn-electrophile batteries to achieve energy output and simultaneous chemical production, (ⅱ) coupling electro-oxidation of nucleophilic pollutants with hybrid direct fuel cells to realize energy output, (ⅲ) applying hybrid water electrolysis systems assisted with nucleophilic wastes for energy-saving and clean H2 production, (ⅳ) assembling Zn-nucleophile batteries for energy storage and hydrogen production, and (ⅴ) producing valuable chemicals via C―N coupling processes. The cell design, coupled with selection criteria and optimizing strategies of advanced electrodes and cell configuration, is highlighted. Finally, an in-depth analysis of current challenges and future prospects is provided to deepen the understanding of advanced electrochemical cells and bridge the gap between experimental trials and practical applications with respect to mechanism investigation, electrode design and evaluation, and cell design.![]()
The interconversion of N2 and N-containing compounds is central to the natural nitrogen cycle, one of the most important global biogeochemical cycles, which plays a crucial role in sustaining life across all organisms. Nitrogen pollution in surface water bodies, caused by the indiscriminate discharge of industrial and domestic wastewater, has become a global environmental concern. The excessive accumulation of nitrogenous wastes poses a serious threat to human health and disrupts the natural nitrogen cycle. Traditional water purification methods, such as chemical redox processes, physical adsorption, and biological treatments, often face limitations, including high energy consumption, low efficiency, large space requirements, prolonged treatment times, sludge generation, and high operating costs. Emerging electrochemical degradation techniques offer promising solutions for efficiently degrading nitrogenous wastes. These electrochemical technologies demonstrate advantages in cost-effectiveness, environmental friendliness, high efficiency, and broad applicability, while also presenting opportunities to generate added value during the electrodegradation processes. Nitrogen-containing wastes in wastewater can be classified into electrophiles (e.g., nitrate and nitrite) and nucleophiles (e.g., ammonia nitrogen, hydrazine, and urea) according to their redox properties. Based on the different properties of nitrogenous wastes, coupling corresponding electrochemical degradation reactions with tailored electrochemical energy storage and conversion devices provides opportunities for additional energy and value generation. Herein, advanced insights into valorization strategies during the electrodegradation processes of representative nitrogenous wastes in sewage are subtly provided, where the approaches for enhanced value output efficiency are highlighted, including (ⅰ) coupling the electroreduction of electrophilic pollutants with Zn-electrophile batteries to achieve energy output and simultaneous chemical production, (ⅱ) coupling electro-oxidation of nucleophilic pollutants with hybrid direct fuel cells to realize energy output, (ⅲ) applying hybrid water electrolysis systems assisted with nucleophilic wastes for energy-saving and clean H2 production, (ⅳ) assembling Zn-nucleophile batteries for energy storage and hydrogen production, and (ⅴ) producing valuable chemicals via C―N coupling processes. The cell design, coupled with selection criteria and optimizing strategies of advanced electrodes and cell configuration, is highlighted. Finally, an in-depth analysis of current challenges and future prospects is provided to deepen the understanding of advanced electrochemical cells and bridge the gap between experimental trials and practical applications with respect to mechanism investigation, electrode design and evaluation, and cell design.
2025, 41(9): 100096
doi: 10.1016/j.actphy.2025.100096
Abstract:
As a critical component for achieving sustainable energy systems, secondary lithium-ion batteries (LIBs) have become the dominant electrochemical energy storage technology. Graphite has been widely employed as an anode material in rechargeable LIBs, where the formation of a solid electrolyte interphase (SEI) on graphite particles plays a pivotal role in realizing optimal Li+ ion storage performance. However, solvent co-intercalation with Li+ ions leads to volumetric expansion, unstable SEI formation, irreversible capacity loss, structural layer collapse, and even lithium dendrite formation. To overcome these challenges, surface coating modification has emerged as an effective strategy to enhance graphite anode performance. This review systematically summarizes recent progress in coating materials (including carbon materials, lithium-ion conductors, metal compounds, and polymers) fabricated through vapor-phase or liquid-phase deposition. Enormous research investigations demonstrate that rationally designed coating layers prevent direct electrolyte/graphite contact to inhibit solvent decomposition, regulate lithium-ion flux distribution to promote uniform deposition, and function as artificial SEI components to improve interphasial stability. This review provides both theoretical insights and practical considerations for future research and development of advanced graphite anode materials for lithium-ion batteries.![]()
As a critical component for achieving sustainable energy systems, secondary lithium-ion batteries (LIBs) have become the dominant electrochemical energy storage technology. Graphite has been widely employed as an anode material in rechargeable LIBs, where the formation of a solid electrolyte interphase (SEI) on graphite particles plays a pivotal role in realizing optimal Li+ ion storage performance. However, solvent co-intercalation with Li+ ions leads to volumetric expansion, unstable SEI formation, irreversible capacity loss, structural layer collapse, and even lithium dendrite formation. To overcome these challenges, surface coating modification has emerged as an effective strategy to enhance graphite anode performance. This review systematically summarizes recent progress in coating materials (including carbon materials, lithium-ion conductors, metal compounds, and polymers) fabricated through vapor-phase or liquid-phase deposition. Enormous research investigations demonstrate that rationally designed coating layers prevent direct electrolyte/graphite contact to inhibit solvent decomposition, regulate lithium-ion flux distribution to promote uniform deposition, and function as artificial SEI components to improve interphasial stability. This review provides both theoretical insights and practical considerations for future research and development of advanced graphite anode materials for lithium-ion batteries.
2025, 41(9): 100117
doi: 10.1016/j.actphy.2025.100117
Abstract:
Hydrogen peroxide (H2O2) is one of the 100 most important chemicals used extensively in bleaching, disinfection, and synthetic chemistry industries. It is currently used as a fuel in direct fuel cells. The current H2O2 production relies on the harsh anthraquinone oxidation approach. Photocatalytic H2O2 production is a more favorable alternative from environmental, sustainability, and economic viewpoints. The process requires water and molecular oxygen as inputs and sunlight as the sole power source. Despite these merits, the practical application of this technology remains challenging. The most common bottlenecks are the photocatalyst's inadequacy, uphill thermodynamics, sluggish process kinetics, and competitive and backward reactions. This paper discusses these limitations and highlights the proposed perspectives to improve the efficiency and selectivity, aiming to pave the way toward large-scale H2O2 photogeneration.![]()
Hydrogen peroxide (H2O2) is one of the 100 most important chemicals used extensively in bleaching, disinfection, and synthetic chemistry industries. It is currently used as a fuel in direct fuel cells. The current H2O2 production relies on the harsh anthraquinone oxidation approach. Photocatalytic H2O2 production is a more favorable alternative from environmental, sustainability, and economic viewpoints. The process requires water and molecular oxygen as inputs and sunlight as the sole power source. Despite these merits, the practical application of this technology remains challenging. The most common bottlenecks are the photocatalyst's inadequacy, uphill thermodynamics, sluggish process kinetics, and competitive and backward reactions. This paper discusses these limitations and highlights the proposed perspectives to improve the efficiency and selectivity, aiming to pave the way toward large-scale H2O2 photogeneration.
2025, 41(9): 100118
doi: 10.1016/j.actphy.2025.100118
Abstract:
With the development of ultrafast laser technology, time-resolved spectroscopy has become an essential tool to study the microscopic photophysical mechanisms on ultrafast time scales in the field of solar energy conversion and utilization. Transient absorption spectroscopy (TAS), as an essential technology for studying photoinduced ultrafast electron transfer and photo-induced carrier dynamics, has the unique advantage of revealing key dynamic processes, such as the generation, separation, transport, and recombination of photogenerated carriers. Focusing on light-to-chemical and light-to-electrical energy conversion, this review summarizes TAS applications in two primary solar energy conversion systems: photocatalysis and solar cells. Firstly, according to the different requirements of photocatalysis (emphasizing migration for surface reactions) and solar cells (highlighting interfacial carrier separation efficiency), we summarize design strategies and recent advances for enhancing carrier utilization from three perspectives: electron manipulation, hole manipulation and surface interfacial processes. Subsequently, special attention is given to how in situ spectroscopy elucidates the influence mechanisms of microscopic energy conversion processes and device performance under complex application scenarios involving photo-electro-thermal couplings. Finally, the forward-looking development direction of basic research in solar energy conversion and utilization is summarized, which provides theoretical support for rational design and performance optimization of solar energy conversion materials, reactions, and devices.![]()
With the development of ultrafast laser technology, time-resolved spectroscopy has become an essential tool to study the microscopic photophysical mechanisms on ultrafast time scales in the field of solar energy conversion and utilization. Transient absorption spectroscopy (TAS), as an essential technology for studying photoinduced ultrafast electron transfer and photo-induced carrier dynamics, has the unique advantage of revealing key dynamic processes, such as the generation, separation, transport, and recombination of photogenerated carriers. Focusing on light-to-chemical and light-to-electrical energy conversion, this review summarizes TAS applications in two primary solar energy conversion systems: photocatalysis and solar cells. Firstly, according to the different requirements of photocatalysis (emphasizing migration for surface reactions) and solar cells (highlighting interfacial carrier separation efficiency), we summarize design strategies and recent advances for enhancing carrier utilization from three perspectives: electron manipulation, hole manipulation and surface interfacial processes. Subsequently, special attention is given to how in situ spectroscopy elucidates the influence mechanisms of microscopic energy conversion processes and device performance under complex application scenarios involving photo-electro-thermal couplings. Finally, the forward-looking development direction of basic research in solar energy conversion and utilization is summarized, which provides theoretical support for rational design and performance optimization of solar energy conversion materials, reactions, and devices.
2025, 41(9): 100097
doi: 10.1016/j.actphy.2025.100097
Abstract:
The management of 137Cs-containing radioactive wastewater from the Fukushima nuclear accident (FNA) has garnered significant attention due to the challenge of its safe disposal. The presence of co-existing Na+ ions severely impedes Cs+ removal, exacerbating the costs associated with radioactive wastewater treatment. Recently, capacitive deionization (CDI) technology has demonstrated significant potential in this field. However, its application is limited by the lack of suitable electrode materials that exhibit high Cs+ selectivity. In this study, we developed a composite of carbon nanotubes (CNT) interspersed potassium zinc ferrocyanide (KZnFC-CNT), which was pre-activated via an electrochemical method, to serve as a CDI cathode for the selective electrosorption of Cs+ ions from saline radioactive wastewater. The KZnFC-CNT electrodes exhibited a maximum electrosorption capacity of 392.75 mg∙g−1, with the highest electrosorption rate of 11.21 mg∙g−1∙min−1. Furthermore, these electrodes exhibited remarkable selectivity, achieving a selectivity factor of 138.2 for Cs+ over Na+ in a Na+ : Cs+ molar ratio of 100 : 1. X-ray diffraction, electrochemical analysis, and theoretical simulations revealed that the selective electrosorption of Cs+ is primarily governed by the ion exchange process between Cs+ and Na+ ions, as well as lattice phase transformations in KZnFC. This study presents an effective approach for the treatment of cesium-containing radioactive wastewater with high salinity.![]()
The management of 137Cs-containing radioactive wastewater from the Fukushima nuclear accident (FNA) has garnered significant attention due to the challenge of its safe disposal. The presence of co-existing Na+ ions severely impedes Cs+ removal, exacerbating the costs associated with radioactive wastewater treatment. Recently, capacitive deionization (CDI) technology has demonstrated significant potential in this field. However, its application is limited by the lack of suitable electrode materials that exhibit high Cs+ selectivity. In this study, we developed a composite of carbon nanotubes (CNT) interspersed potassium zinc ferrocyanide (KZnFC-CNT), which was pre-activated via an electrochemical method, to serve as a CDI cathode for the selective electrosorption of Cs+ ions from saline radioactive wastewater. The KZnFC-CNT electrodes exhibited a maximum electrosorption capacity of 392.75 mg∙g−1, with the highest electrosorption rate of 11.21 mg∙g−1∙min−1. Furthermore, these electrodes exhibited remarkable selectivity, achieving a selectivity factor of 138.2 for Cs+ over Na+ in a Na+ : Cs+ molar ratio of 100 : 1. X-ray diffraction, electrochemical analysis, and theoretical simulations revealed that the selective electrosorption of Cs+ is primarily governed by the ion exchange process between Cs+ and Na+ ions, as well as lattice phase transformations in KZnFC. This study presents an effective approach for the treatment of cesium-containing radioactive wastewater with high salinity.
2025, 41(9): 100098
doi: 10.1016/j.actphy.2025.100098
Abstract:
In recent years, single-junction perovskite solar cells (PSCs) have experienced unprecedented development, approaching the Shockley-Queisser (S-Q) theoretical efficiency limit, due to versatile optimization strategies targeting functional layers to minimize energy loss. The antireflection coating (ARC), as part of the light-management strategy, plays a critical role in reducing optical loss to achieve higher efficiency. The development of multifunctional ARC that can simultaneously enhance visible light transmittance while suppressing ultraviolet (UV) light transmission, along with excellent adhesion and wear resistance on glass substrates, remains a significant challenge in current research. Herein, we propose ultra-thin ARC made of multilayer dioxides, SiO2-TiO2-SiO2 (STS) films, optimized using a machine learning approach with a Bayesian optimization algorithm. This process involved parameterized modeling of multilayer dioxide ARC, physical simulations using the Transfer Matrix Method (TMM), and evaluation of antireflective performance. The optimal configuration of STS ARC consists of 100 nm SiO2, 10 nm TiO2, and 10 nm SiO2, increasing the transmittance of FTO glass by 9.2% in the 400–800 nm wavelength range. The ARC effectively enhances external quantum efficiency, achieving 96.94%, thereby increasing the short-circuit current density (JSC) and power conversion efficiency (PCE) by 4%. PSCs with STS ARC retain 81.2% of their initial efficiency after continuous UV illumination for 300 h, while control devices degrade to approximately 69%, demonstrating effective UV filtration and improved operational stability. This ARC exhibit hardness exceeding 9H on the pencil hardness scale and achieve ISO class 0/ASTM class 5B in adhesion tests, meeting the outdoor durability requirements for PSCs. In addition to optical energy loss, the accumulation of defects on the surface of the perovskite layer induces non-radiative recombination energy loss and serves as initiation sites for lattice degradation. To address this, we use 3-amidinopyridinium iodide (3-PyADI) to passivate interface defects, further improving the PCE to 24.44%. The stability of the device remains at 93% of the initial PCE after 1000 h under atmospheric conditions. The proposed ARC and PSCs structure are expected to enhance optoelectronic performance and environmental stability, providing a promising and practical path for the development of PSCs.
In recent years, single-junction perovskite solar cells (PSCs) have experienced unprecedented development, approaching the Shockley-Queisser (S-Q) theoretical efficiency limit, due to versatile optimization strategies targeting functional layers to minimize energy loss. The antireflection coating (ARC), as part of the light-management strategy, plays a critical role in reducing optical loss to achieve higher efficiency. The development of multifunctional ARC that can simultaneously enhance visible light transmittance while suppressing ultraviolet (UV) light transmission, along with excellent adhesion and wear resistance on glass substrates, remains a significant challenge in current research. Herein, we propose ultra-thin ARC made of multilayer dioxides, SiO2-TiO2-SiO2 (STS) films, optimized using a machine learning approach with a Bayesian optimization algorithm. This process involved parameterized modeling of multilayer dioxide ARC, physical simulations using the Transfer Matrix Method (TMM), and evaluation of antireflective performance. The optimal configuration of STS ARC consists of 100 nm SiO2, 10 nm TiO2, and 10 nm SiO2, increasing the transmittance of FTO glass by 9.2% in the 400–800 nm wavelength range. The ARC effectively enhances external quantum efficiency, achieving 96.94%, thereby increasing the short-circuit current density (JSC) and power conversion efficiency (PCE) by 4%. PSCs with STS ARC retain 81.2% of their initial efficiency after continuous UV illumination for 300 h, while control devices degrade to approximately 69%, demonstrating effective UV filtration and improved operational stability. This ARC exhibit hardness exceeding 9H on the pencil hardness scale and achieve ISO class 0/ASTM class 5B in adhesion tests, meeting the outdoor durability requirements for PSCs. In addition to optical energy loss, the accumulation of defects on the surface of the perovskite layer induces non-radiative recombination energy loss and serves as initiation sites for lattice degradation. To address this, we use 3-amidinopyridinium iodide (3-PyADI) to passivate interface defects, further improving the PCE to 24.44%. The stability of the device remains at 93% of the initial PCE after 1000 h under atmospheric conditions. The proposed ARC and PSCs structure are expected to enhance optoelectronic performance and environmental stability, providing a promising and practical path for the development of PSCs.
2025, 41(9): 100099
doi: 10.1016/j.actphy.2025.100099
Abstract:
Solar-driven photothermal catalytic CO2 conversion with H2O is a promising approach to produce sustainable fuels and chemicals. However, the competition between hydrogen evolution reaction (HER) and CO2 reduction reaction (CO2RR) results in unsatisfactory product selectivity. Noble metal nanoparticles (NMNPs) are widely used cocatalysts to introduce active sites on semiconductors, with unique active sites at the metal-semiconductor interfacial edges playing a critical role in the competitive mechanisms. Herein, we prepared a series of NMNPs loaded on Al-doped SrTiO3 with abundant interfacial edge sites for continuous photothermal catalytic CO2 and H2O conversion. Different NMNPs demonstrated distinct CO2-induced effects on hydrogen evolution. The key intermediate interactions were investigated by in situ diffuse reflectance infrared Fourier-transform spectroscopy (DRIFTS) and density functional theory (DFT) calculations. The results revealed that bidentate carbonate (b-CO32−) tended to occupy the edge sites at the metal-semiconductor interfaces, competitively consuming the active sites for *H adsorption and altering the energy barrier of hydrogen evolution. The predominant site-blocking effect of b-CO32− on Rh-loaded catalysts was verified through establishing a simplified geometric model to quantify the correlation of particle sizes, active site proportions and CO2-induced hydrogen production variations. Controlling Rh nanoparticle size can tune the proportion of edge sites, which involves a trade-off between *H coverage and CO2 activation and promotes the CO2RR process toward methane production. This work initially unravels the interfacial competitive mechanism between HER and CO2RR via edge-active-site modulation, hoping to provide valuable insights for the rational catalyst design and offer potential strategies to enhance CO2 conversion efficiency.
Solar-driven photothermal catalytic CO2 conversion with H2O is a promising approach to produce sustainable fuels and chemicals. However, the competition between hydrogen evolution reaction (HER) and CO2 reduction reaction (CO2RR) results in unsatisfactory product selectivity. Noble metal nanoparticles (NMNPs) are widely used cocatalysts to introduce active sites on semiconductors, with unique active sites at the metal-semiconductor interfacial edges playing a critical role in the competitive mechanisms. Herein, we prepared a series of NMNPs loaded on Al-doped SrTiO3 with abundant interfacial edge sites for continuous photothermal catalytic CO2 and H2O conversion. Different NMNPs demonstrated distinct CO2-induced effects on hydrogen evolution. The key intermediate interactions were investigated by in situ diffuse reflectance infrared Fourier-transform spectroscopy (DRIFTS) and density functional theory (DFT) calculations. The results revealed that bidentate carbonate (b-CO32−) tended to occupy the edge sites at the metal-semiconductor interfaces, competitively consuming the active sites for *H adsorption and altering the energy barrier of hydrogen evolution. The predominant site-blocking effect of b-CO32− on Rh-loaded catalysts was verified through establishing a simplified geometric model to quantify the correlation of particle sizes, active site proportions and CO2-induced hydrogen production variations. Controlling Rh nanoparticle size can tune the proportion of edge sites, which involves a trade-off between *H coverage and CO2 activation and promotes the CO2RR process toward methane production. This work initially unravels the interfacial competitive mechanism between HER and CO2RR via edge-active-site modulation, hoping to provide valuable insights for the rational catalyst design and offer potential strategies to enhance CO2 conversion efficiency.
2025, 41(9): 100100
doi: 10.1016/j.actphy.2025.100100
Abstract:
Ethanol dehydrogenation is a vital elementary step in ethanol upgrading, for which Cu-based alloy catalysts are the most promising candidates. Nevertheless, elucidating the underlying reasons for the synergistic effect between alloying components and host metals remains challenging due to the intrinsic structural complexity and dynamic evolution of alloy catalysts under operational conditions. Herein, single-atom Pd modified Cu-MFI catalysts with well-defined structures were designed for ethanol dehydrogenation to acetaldehyde and hydrogen. Comprehensive characterizations using aberration-corrected high-angle annular dark-field scanning transmission electron microscopy (AC-HAADF-STEM), X-ray absorption spectroscopy (XAS), X-ray photoelectron spectroscopy (XPS) and density functional theory (DFT) calculations revealed that Pd atoms are isolated by surrounding Cu atoms with a coordination number of 9–10, forming −0.36e charged single-atom sites and being uniformly dispersed on the surface of Cu catalysts. The newly generated Pdδ− and Cuδ+ sites synergistically reduced the activation energy barrier for C—H bond cleavage in ethanol. These sites simultaneously enhanced hydrogen adsorption and H—H bond coupling, leading to improved ethanol conversion and acetaldehyde productivity over Pd/Cu-MFI catalysts.
Ethanol dehydrogenation is a vital elementary step in ethanol upgrading, for which Cu-based alloy catalysts are the most promising candidates. Nevertheless, elucidating the underlying reasons for the synergistic effect between alloying components and host metals remains challenging due to the intrinsic structural complexity and dynamic evolution of alloy catalysts under operational conditions. Herein, single-atom Pd modified Cu-MFI catalysts with well-defined structures were designed for ethanol dehydrogenation to acetaldehyde and hydrogen. Comprehensive characterizations using aberration-corrected high-angle annular dark-field scanning transmission electron microscopy (AC-HAADF-STEM), X-ray absorption spectroscopy (XAS), X-ray photoelectron spectroscopy (XPS) and density functional theory (DFT) calculations revealed that Pd atoms are isolated by surrounding Cu atoms with a coordination number of 9–10, forming −0.36e charged single-atom sites and being uniformly dispersed on the surface of Cu catalysts. The newly generated Pdδ− and Cuδ+ sites synergistically reduced the activation energy barrier for C—H bond cleavage in ethanol. These sites simultaneously enhanced hydrogen adsorption and H—H bond coupling, leading to improved ethanol conversion and acetaldehyde productivity over Pd/Cu-MFI catalysts.
2025, 41(9): 100104
doi: 10.1016/j.actphy.2025.100104
Abstract:
With the rapid development of new energy industries, the utilization of waste batteries has attracted the attention of researchers. Developing a hydrogen peroxide photosynthesis system with battery recycling materials as photocatalysts presents a significant challenge. In this study, an ultrasonic self-assembly technique is employed to integrate LiFePO4 (LFPO) nanoparticles, derived from spent batteries, with g-C3N4 (CN) nanosheets, thereby creating an inorganic/organic S-scheme photocatalyst for the production of H2O2. In situ analyses using X-ray photoelectron spectroscopy (XPS) and Kelvin probe force microscopy (KPFM) demonstrate that the interaction between LFPO and CN facilitates the development of an internal electric field (IEF), which in turn gives rise to a distinctive S-scheme charge transfer mechanism. Combining electron spin resonance spectroscopy, radical-trapping experiments, and in situ DRIFTS spectra, three pathways for H2O2 formation are identified. Benefited from enhanced carrier separation, strong redox power, and multichannel H2O2 formation, the optimal composite shows an impressive H2O2-production rate of 3.22 mol∙g−1∙h−1 under simulated solar irradiation. This research provides a potential method to investigate a sustainable H2O2 photosynthesis pathway by designing S-scheme heterojunctions from spent battery materials.
With the rapid development of new energy industries, the utilization of waste batteries has attracted the attention of researchers. Developing a hydrogen peroxide photosynthesis system with battery recycling materials as photocatalysts presents a significant challenge. In this study, an ultrasonic self-assembly technique is employed to integrate LiFePO4 (LFPO) nanoparticles, derived from spent batteries, with g-C3N4 (CN) nanosheets, thereby creating an inorganic/organic S-scheme photocatalyst for the production of H2O2. In situ analyses using X-ray photoelectron spectroscopy (XPS) and Kelvin probe force microscopy (KPFM) demonstrate that the interaction between LFPO and CN facilitates the development of an internal electric field (IEF), which in turn gives rise to a distinctive S-scheme charge transfer mechanism. Combining electron spin resonance spectroscopy, radical-trapping experiments, and in situ DRIFTS spectra, three pathways for H2O2 formation are identified. Benefited from enhanced carrier separation, strong redox power, and multichannel H2O2 formation, the optimal composite shows an impressive H2O2-production rate of 3.22 mol∙g−1∙h−1 under simulated solar irradiation. This research provides a potential method to investigate a sustainable H2O2 photosynthesis pathway by designing S-scheme heterojunctions from spent battery materials.
2025, 41(9): 100105
doi: 10.1016/j.actphy.2025.100105
Abstract:
g-C3N4/Bi2WO6 (MCN/BWO) heterojunction photocatalysts were synthesized via a one-step hydrothermal method for the degradation of levofloxacin (LEV). Under simulated sunlight irradiation, the degradation rate of LEV by MCN/BWO with a molar ratio of 1 : 1 reached 98.14%, which was attributed to the formation of an S-scheme heterojunction between MCN and BWO. In situ XPS analysis and surface work function measurements confirmed that the electron transfer pathway follows the S-scheme heterojunction mechanism. The internal electric field (IEF) generated by the S-scheme heterojunction in the MCN/BWO system facilitates direct transfer of photogenerated electrons (e−) from the conduction band (CB) of BWO to the valence band (VB) of MCN. This process enables efficient separation of photogenerated electron-hole (e−-h+) pairs, with h⁺ accumulating on the VB of BWO and e− accumulating on the CB of MCN. Free radical trapping experiments demonstrated that the superoxide free radical (·O₂−) and h⁺ were the primary active species. Besides exhibiting superior photocatalytic performance, the catalyst maintained excellent stability over three consecutive cycles. To elucidate the degradation mechanism, liquid chromatography-mass spectrometry (LC-MS) and quantitative structure-activity relationship (QSAR) analysis were employed to identify degradation pathways, intermediates, and potential toxicity. This study provides a theoretical foundation for wastewater treatment applications.
g-C3N4/Bi2WO6 (MCN/BWO) heterojunction photocatalysts were synthesized via a one-step hydrothermal method for the degradation of levofloxacin (LEV). Under simulated sunlight irradiation, the degradation rate of LEV by MCN/BWO with a molar ratio of 1 : 1 reached 98.14%, which was attributed to the formation of an S-scheme heterojunction between MCN and BWO. In situ XPS analysis and surface work function measurements confirmed that the electron transfer pathway follows the S-scheme heterojunction mechanism. The internal electric field (IEF) generated by the S-scheme heterojunction in the MCN/BWO system facilitates direct transfer of photogenerated electrons (e−) from the conduction band (CB) of BWO to the valence band (VB) of MCN. This process enables efficient separation of photogenerated electron-hole (e−-h+) pairs, with h⁺ accumulating on the VB of BWO and e− accumulating on the CB of MCN. Free radical trapping experiments demonstrated that the superoxide free radical (·O₂−) and h⁺ were the primary active species. Besides exhibiting superior photocatalytic performance, the catalyst maintained excellent stability over three consecutive cycles. To elucidate the degradation mechanism, liquid chromatography-mass spectrometry (LC-MS) and quantitative structure-activity relationship (QSAR) analysis were employed to identify degradation pathways, intermediates, and potential toxicity. This study provides a theoretical foundation for wastewater treatment applications.
2025, 41(9): 100106
doi: 10.1016/j.actphy.2025.100106
Abstract:
Aqueous zinc-ion batteries (AZIBs) have gained considerable attention as next-generation energy storage devices due to their inherent safety, environmental friendliness, and cost-effectiveness. However, their widespread application is severely hampered by uncontrolled zinc dendrite growth and detrimental side reactions (e.g., hydrogen evolution, corrosion, and passivation), which lead to reduced Coulombic efficiency and shortened cycle life. Current strategies to improve zinc anode stability mainly focus on artificial interface coatings, electrode structure design, and electrolyte optimization. Among these approaches, electrolyte additive engineering is considered the most promising for practical applications due to its simplicity, low cost, and excellent scalability. Nevertheless, conventional additives (including metal ions, polymers, and surfactants) typically address only single issues (either dendrite suppression or side reaction mitigation), failing to achieve synergistic effects. In this work, we developed sulfur-doped carbon dots (S-CDs) as a novel bifunctional electrolyte additive to significantly enhance AZIB performance. The carbon dot additive was synthesized via a facile calcination method, followed by systematic characterization of its structure and properties using methods such as Fourier transform infrared spectroscopy (FT-IR), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), and density functional theory (DFT) calculations. Comprehensive electrochemical evaluations were conducted to investigate the influence of S-CDs on zinc deposition behavior and overall battery performance. Experimental results demonstrate the successful synthesis of sulfur-doped carbon dots with abundant surface functional groups. During battery operation, the strong binding affinity between S-CDs and Zn2+ effectively reconstructs the Zn2+ solvation shell, reducing water molecule content and thereby minimizing electrode corrosion and side reactions caused by interfacial active water molecules. Moreover, the S-CDs induce the formation of stable (002) crystallographic planes that continuously renew during plating/stripping cycles, with particularly pronounced effects under high current densities, significantly enhancing the structural stability of the electrode. The synergistic effect of these dual functions leads to remarkable improvement in zinc electrode performance and ultimately endows the battery with ultra-long cycling life. Benefiting from the positive effects of the carbon dot additive, the symmetric cell achieves exceptional stability for nearly 2000 h at a high current density of 10 mA∙cm−2, far outperforming conventional electrolyte systems. Furthermore, both Zn||NH4V4O10 and Zn||MnO2 full cells exhibit superior electrochemical performance and significantly enhanced cycling stability, confirming the excellent compatibility of the carbon dot additive with various cathode materials. This study provides novel insights and fundamental theoretical guidance for developing high-performance AZIBs, representing a significant advancement in sustainable energy storage technologies.![]()
Aqueous zinc-ion batteries (AZIBs) have gained considerable attention as next-generation energy storage devices due to their inherent safety, environmental friendliness, and cost-effectiveness. However, their widespread application is severely hampered by uncontrolled zinc dendrite growth and detrimental side reactions (e.g., hydrogen evolution, corrosion, and passivation), which lead to reduced Coulombic efficiency and shortened cycle life. Current strategies to improve zinc anode stability mainly focus on artificial interface coatings, electrode structure design, and electrolyte optimization. Among these approaches, electrolyte additive engineering is considered the most promising for practical applications due to its simplicity, low cost, and excellent scalability. Nevertheless, conventional additives (including metal ions, polymers, and surfactants) typically address only single issues (either dendrite suppression or side reaction mitigation), failing to achieve synergistic effects. In this work, we developed sulfur-doped carbon dots (S-CDs) as a novel bifunctional electrolyte additive to significantly enhance AZIB performance. The carbon dot additive was synthesized via a facile calcination method, followed by systematic characterization of its structure and properties using methods such as Fourier transform infrared spectroscopy (FT-IR), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), and density functional theory (DFT) calculations. Comprehensive electrochemical evaluations were conducted to investigate the influence of S-CDs on zinc deposition behavior and overall battery performance. Experimental results demonstrate the successful synthesis of sulfur-doped carbon dots with abundant surface functional groups. During battery operation, the strong binding affinity between S-CDs and Zn2+ effectively reconstructs the Zn2+ solvation shell, reducing water molecule content and thereby minimizing electrode corrosion and side reactions caused by interfacial active water molecules. Moreover, the S-CDs induce the formation of stable (002) crystallographic planes that continuously renew during plating/stripping cycles, with particularly pronounced effects under high current densities, significantly enhancing the structural stability of the electrode. The synergistic effect of these dual functions leads to remarkable improvement in zinc electrode performance and ultimately endows the battery with ultra-long cycling life. Benefiting from the positive effects of the carbon dot additive, the symmetric cell achieves exceptional stability for nearly 2000 h at a high current density of 10 mA∙cm−2, far outperforming conventional electrolyte systems. Furthermore, both Zn||NH4V4O10 and Zn||MnO2 full cells exhibit superior electrochemical performance and significantly enhanced cycling stability, confirming the excellent compatibility of the carbon dot additive with various cathode materials. This study provides novel insights and fundamental theoretical guidance for developing high-performance AZIBs, representing a significant advancement in sustainable energy storage technologies.
2025, 41(9): 100107
doi: 10.1016/j.actphy.2025.100107
Abstract:
The van der Waals heterojunctions demonstrate exceptional advantages due to their outstanding charge separation capabilities and remarkable flexibility in tuning electronic properties. This study explores the potential application of the 2D/2D g-C3N4 @BN van der Waals heterojunction in the photocatalytic synthesis of hydrogen peroxide (H2O2). Based on this heterojunction, we investigated the energy transfer process between triplet excitons and singlet oxygen, emphasizing the importance of catalyst structure for charge separation and the stable generation of triplet electrons. By constructing a charge transfer pathway, the built-in electric field within the heterojunction effectively drives the directional migration of charge carriers, significantly extending their lifetime. We employed two modification strategies to regulate the excited state electronic properties of the catalyst, including adjusting the interlayer arrangement to enhance charge transport capability and halogen modification to improve the light responsiveness of materials. Experimental validation indicates that the representative chlorinated-CN@BN effectively suppresses exciton recombination compared to CN, extending the lifetime of excited-state carriers by 3.52 times. Furthermore, the photocatalytic yield of H2O2 is improved by 2.73 times. This study provides a theoretical basis for developing novel photocatalysts and inspires the design of catalysts for direct synthesis of H2O2 from oxygen.![]()
The van der Waals heterojunctions demonstrate exceptional advantages due to their outstanding charge separation capabilities and remarkable flexibility in tuning electronic properties. This study explores the potential application of the 2D/2D g-C3N4 @BN van der Waals heterojunction in the photocatalytic synthesis of hydrogen peroxide (H2O2). Based on this heterojunction, we investigated the energy transfer process between triplet excitons and singlet oxygen, emphasizing the importance of catalyst structure for charge separation and the stable generation of triplet electrons. By constructing a charge transfer pathway, the built-in electric field within the heterojunction effectively drives the directional migration of charge carriers, significantly extending their lifetime. We employed two modification strategies to regulate the excited state electronic properties of the catalyst, including adjusting the interlayer arrangement to enhance charge transport capability and halogen modification to improve the light responsiveness of materials. Experimental validation indicates that the representative chlorinated-CN@BN effectively suppresses exciton recombination compared to CN, extending the lifetime of excited-state carriers by 3.52 times. Furthermore, the photocatalytic yield of H2O2 is improved by 2.73 times. This study provides a theoretical basis for developing novel photocatalysts and inspires the design of catalysts for direct synthesis of H2O2 from oxygen.
2025, 41(9): 100109
doi: 10.1016/j.actphy.2025.100109
Abstract:
Carbon dots (CDs) have emerged as promising photothermal agents for near-infrared (NIR)-mediated tumor therapy due to their excellent biocompatibility and tunable optical properties. However, it is still unclear how to precisely control their assembly behavior to enhance NIR absorption and photothermal conversion efficiency. In this work, we present a hyper-assembled electron donor/acceptor CDs complex (S-d/a-CDs), constructed by integrating electron-donating CDs (d-CDs) with electron-withdrawing CDs (a-CDs). This configuration significantly enhances the NIR absorption capacity of S-d/a-CDs. Under 740 nm laser irradiation, S-d/a-CDs achieve a remarkable photothermal conversion efficiency (PTCE) of 65.8%. S-d/a-CDs exhibit negligible cytotoxicity and effective tumor accumulation capacity through intravenous administration, enabling complete tumor elimination after NIR laser irradiation. To our knowledge, this study is the first to exploit synergistic assembles of two types of CDs for photo-physical property engineering, establishing a groundbreaking paradigm for the development of advanced NIR-triggered photothermal materials.![]()
Carbon dots (CDs) have emerged as promising photothermal agents for near-infrared (NIR)-mediated tumor therapy due to their excellent biocompatibility and tunable optical properties. However, it is still unclear how to precisely control their assembly behavior to enhance NIR absorption and photothermal conversion efficiency. In this work, we present a hyper-assembled electron donor/acceptor CDs complex (S-d/a-CDs), constructed by integrating electron-donating CDs (d-CDs) with electron-withdrawing CDs (a-CDs). This configuration significantly enhances the NIR absorption capacity of S-d/a-CDs. Under 740 nm laser irradiation, S-d/a-CDs achieve a remarkable photothermal conversion efficiency (PTCE) of 65.8%. S-d/a-CDs exhibit negligible cytotoxicity and effective tumor accumulation capacity through intravenous administration, enabling complete tumor elimination after NIR laser irradiation. To our knowledge, this study is the first to exploit synergistic assembles of two types of CDs for photo-physical property engineering, establishing a groundbreaking paradigm for the development of advanced NIR-triggered photothermal materials.
2025, 41(9): 100111
doi: 10.1016/j.actphy.2025.100111
Abstract:
Understanding the activity-determining factors governing the alkaline hydrogen evolution reaction (HER) on transition metal catalysts is indispensable for water electrolysis with renewable energy. However, it remains a critical challenge. Although hydroxyl adsorption has been proposed to influence alkaline HER performance, its exact mechanistic role and quantitative correlations remain elusive. Here, we systematically investigate the alkaline HER on ten transition metal surfaces using density functional theory (DFT), revealing that hydroxyl adsorption critically modulates both pathway selection and reaction energy barrier. However, hydroxyl adsorption energy alone cannot fully explain the anomalous activity of certain catalysts, especially Pt. To address this, we introduce a multi-parameter coupled descriptor (ECS) that integrates electron occupancy (E), adsorption configuration (C), and surface crystallographic (S), enabling a qualitative evaluation of catalytic activity. This descriptor successfully elucidates previously unexplained activity trends and demonstrates a good correlation with over 10 experimental datasets, including those involving single-atom alloy (SAA) catalysts, indicating its robustness beyond pure metals. Our findings provide a descriptor based on the key species of hydroxyl for rational catalyst design and screening, and offer a fundamental framework for advancing the development of high-performance alkaline HER catalysts.![]()
Understanding the activity-determining factors governing the alkaline hydrogen evolution reaction (HER) on transition metal catalysts is indispensable for water electrolysis with renewable energy. However, it remains a critical challenge. Although hydroxyl adsorption has been proposed to influence alkaline HER performance, its exact mechanistic role and quantitative correlations remain elusive. Here, we systematically investigate the alkaline HER on ten transition metal surfaces using density functional theory (DFT), revealing that hydroxyl adsorption critically modulates both pathway selection and reaction energy barrier. However, hydroxyl adsorption energy alone cannot fully explain the anomalous activity of certain catalysts, especially Pt. To address this, we introduce a multi-parameter coupled descriptor (ECS) that integrates electron occupancy (E), adsorption configuration (C), and surface crystallographic (S), enabling a qualitative evaluation of catalytic activity. This descriptor successfully elucidates previously unexplained activity trends and demonstrates a good correlation with over 10 experimental datasets, including those involving single-atom alloy (SAA) catalysts, indicating its robustness beyond pure metals. Our findings provide a descriptor based on the key species of hydroxyl for rational catalyst design and screening, and offer a fundamental framework for advancing the development of high-performance alkaline HER catalysts.
2025, 41(9): 100116
doi: 10.1016/j.actphy.2025.100116
Abstract:
S-scheme heterojunctions have garnered significant interest in photocatalytic CO2 conversion to valuable products (e.g., CH4) due to their enhanced charge separation and robust redox capabilities. Carbon dots (CDs), with their tunable band structures and light absorption ranges, show particular promise in constructing efficient S-scheme photocatalytic systems. Nevertheless, the critical roles of CDs' band alignment and surface adsorption properties in determining heterojunction configuration, charge carrier kinetics, and ultimately CO2 activation/product selectivity distribution remain insufficiently explored. Herein, we construct four CDs/TiO2 heterojunctions using CDs synthesized from varied carbon sources, in which S-scheme heterojunctions were successfully constructed based on cost-effective coal pitch (C-GQDs, 1.75 nm), glucose (G-CQDs, 1.84 nm), and acetone (CQDs-X, 1.82 nm) carbon sources, whereas Type-Ⅰ heterojunctions were formed by carbon black based CDs (GQDs-A, 1.92 nm). Systematic investigations reveal that both the band structure and adsorption characteristics of CDs play important roles in the charge transfer path and separation efficiency, CO2 adsorption and activation capacities, and product selectivity in photocatalytic CO2 reduction. Remarkably, the introduction of CDs significantly broadens the photo-response range compared to fresh TiO2, and in particular, the C-GQDs/TiO2 exhibits exceptional performance with a CH4 production rate of 32.7 μmol·g−1·h−1, surpassing TiO2 by 6.3-fold and outperforming GQDs-A/TiO2, CQDs-X/TiO2, and G-CQDs/TiO2 by factors of 3.8, 2.7, and 2.3, respectively. This heterojunction simultaneously achieves 72.6% CH4 selectivity and 98.1% hydrocarbons selectivity (encompassing CH4, C2H6, C2H4, and C3H8). In contrast, composites incorporating GQDs-A, CQDs-X, or G-CQDs exhibit substantially diminished CH4 selectivity (< 40.0%). The high CH4 production rate and selectivity of C-GQDs/TiO2 can be attributed to its unique S-scheme heterojunction structure, higher reduction potential, and well-matched CO2 and H2O adsorption and activation capabilities. This study provides unique insights into the efficient photoreduction of CO2 to CH4 driven by the S-scheme heterojunction electron transfer pathway in CDs/TiO2 photocatalysts.![]()
S-scheme heterojunctions have garnered significant interest in photocatalytic CO2 conversion to valuable products (e.g., CH4) due to their enhanced charge separation and robust redox capabilities. Carbon dots (CDs), with their tunable band structures and light absorption ranges, show particular promise in constructing efficient S-scheme photocatalytic systems. Nevertheless, the critical roles of CDs' band alignment and surface adsorption properties in determining heterojunction configuration, charge carrier kinetics, and ultimately CO2 activation/product selectivity distribution remain insufficiently explored. Herein, we construct four CDs/TiO2 heterojunctions using CDs synthesized from varied carbon sources, in which S-scheme heterojunctions were successfully constructed based on cost-effective coal pitch (C-GQDs, 1.75 nm), glucose (G-CQDs, 1.84 nm), and acetone (CQDs-X, 1.82 nm) carbon sources, whereas Type-Ⅰ heterojunctions were formed by carbon black based CDs (GQDs-A, 1.92 nm). Systematic investigations reveal that both the band structure and adsorption characteristics of CDs play important roles in the charge transfer path and separation efficiency, CO2 adsorption and activation capacities, and product selectivity in photocatalytic CO2 reduction. Remarkably, the introduction of CDs significantly broadens the photo-response range compared to fresh TiO2, and in particular, the C-GQDs/TiO2 exhibits exceptional performance with a CH4 production rate of 32.7 μmol·g−1·h−1, surpassing TiO2 by 6.3-fold and outperforming GQDs-A/TiO2, CQDs-X/TiO2, and G-CQDs/TiO2 by factors of 3.8, 2.7, and 2.3, respectively. This heterojunction simultaneously achieves 72.6% CH4 selectivity and 98.1% hydrocarbons selectivity (encompassing CH4, C2H6, C2H4, and C3H8). In contrast, composites incorporating GQDs-A, CQDs-X, or G-CQDs exhibit substantially diminished CH4 selectivity (< 40.0%). The high CH4 production rate and selectivity of C-GQDs/TiO2 can be attributed to its unique S-scheme heterojunction structure, higher reduction potential, and well-matched CO2 and H2O adsorption and activation capabilities. This study provides unique insights into the efficient photoreduction of CO2 to CH4 driven by the S-scheme heterojunction electron transfer pathway in CDs/TiO2 photocatalysts.
