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2022 Volume 41 Issue 10
2022, 41(10): 221000
doi: 10.14102/j.cnki.0254-5861.2022-0164
Abstract:
LMR materials contain two structures (i.e., LiTMO2 and Li2MnO3) that exhibit different electrochemical behaviors during charging/discharging. Limited by characterization techniques, this process is difficult to observe. The LiTMO2 and Li2MnO3 domains share a coherent lattice at the nanoscale but exhibit differentiated electrochemical activities due to different redox chemistries. By probing the origin of structural instability, it is suggested that the lattice strain observed not only affects the electrochemical performance of LMR, but also has implication in other layered cathode materials for Li-ion batteries.![]()
2022, 41(10): 221000
doi: 10.14102/j.cnki.0254-5861.2022-0083
Abstract:
A comprehensive understanding of the microscopic reaction mechanisms at the gas-solid-liquid electrochemical interfaces is urgently required for the development of advanced electrocatalysts applied in burgeoning sustainable energy conversion systems. In-situ synchrotron radiation Fourier transform infrared (SR-FTIR) spectroscopy is one of the most powerful techniques for investigating the evolving dynamics of reactive intermediates during electrocatalytic reactions. In this review, we methodically summarize the recent progress in the research of dynamic mechanisms for valuable electrocatalytic reactions based on in-situ SR-FTIR methodology. Moreover, the merits and drawbacks of SR-FTIR spectroscopy, the design principles of infrared beam setups and in-situ cells, as well as the in-situ measurement criteria are also discussed in detail. Lastly, the potential challenges and opportunities in this field are prudently stated. This review is expected to stimulate a broad interest in the material science and electrochemistry communities for exploring the dynamic mechanisms of prominent catalysis at the atomic/molecular level by using SR-based spectroscopy.
A comprehensive understanding of the microscopic reaction mechanisms at the gas-solid-liquid electrochemical interfaces is urgently required for the development of advanced electrocatalysts applied in burgeoning sustainable energy conversion systems. In-situ synchrotron radiation Fourier transform infrared (SR-FTIR) spectroscopy is one of the most powerful techniques for investigating the evolving dynamics of reactive intermediates during electrocatalytic reactions. In this review, we methodically summarize the recent progress in the research of dynamic mechanisms for valuable electrocatalytic reactions based on in-situ SR-FTIR methodology. Moreover, the merits and drawbacks of SR-FTIR spectroscopy, the design principles of infrared beam setups and in-situ cells, as well as the in-situ measurement criteria are also discussed in detail. Lastly, the potential challenges and opportunities in this field are prudently stated. This review is expected to stimulate a broad interest in the material science and electrochemistry communities for exploring the dynamic mechanisms of prominent catalysis at the atomic/molecular level by using SR-based spectroscopy.
2022, 41(10): 221001
doi: 10.14102/j.cnki.0254-5861.2022-0099
Abstract:
Photo/electrocatalytic water splitting has been considered as one of the most promising approaches for the clean hydrogen production. Among various photo/electrocatalysts, 2D nanomaterials exhibit great potential because of their conspicuous properties. Meanwhile, synchrotron-based soft X-ray absorption spectroscopy (XAS) as a powerful and element-specific technique has been widely used to explore the electronic structure of 2D photo/electrocatalysts to comprehensively understand their working mechanism for the development of high-performance catalysts. In this work, the recent developments of soft XAS techniques applied in 2D photo/electrocatalysts have been reviewed, mainly focusing on identifying the surface active sites, elucidating the location of heteroatoms, and unraveling the interfacial interaction in the composite. The challenges and outlook in this research field have also been emphasized. The present review provides an in-depth understanding on how soft XAS techniques unravel the correlations between structure and performance in 2D photo/electrocatalysts, which could guide the rational design of highly efficient catalysts for photo/electrocatalytic water splitting.
Photo/electrocatalytic water splitting has been considered as one of the most promising approaches for the clean hydrogen production. Among various photo/electrocatalysts, 2D nanomaterials exhibit great potential because of their conspicuous properties. Meanwhile, synchrotron-based soft X-ray absorption spectroscopy (XAS) as a powerful and element-specific technique has been widely used to explore the electronic structure of 2D photo/electrocatalysts to comprehensively understand their working mechanism for the development of high-performance catalysts. In this work, the recent developments of soft XAS techniques applied in 2D photo/electrocatalysts have been reviewed, mainly focusing on identifying the surface active sites, elucidating the location of heteroatoms, and unraveling the interfacial interaction in the composite. The challenges and outlook in this research field have also been emphasized. The present review provides an in-depth understanding on how soft XAS techniques unravel the correlations between structure and performance in 2D photo/electrocatalysts, which could guide the rational design of highly efficient catalysts for photo/electrocatalytic water splitting.
2022, 41(10): 221002
doi: 10.14102/j.cnki.0254-5861.2022-0136
Abstract:
Heterogeneous catalysis taking place at solid interfaces plays a crucial role not only in industrial chemical production, energy conversion but also in fundamental research. The dynamic evolution of surface morphology and composition requires full understanding especially under realistic reaction conditions. To this end, conventional scanning tunneling microscopy (STM) has been integrated with high pressure cell and electrochemical cell, forming high pressure (HP) STM and electrochemical (EC) STM for the in-situ/operando characterization at solid-gas and solid-liquid interfaces with atomic resolution, respectively. In this review, we attempt to give a brief introduction to the development and working principle of these two techniques and subsequently summarize several representative progresses in recent days. The dynamic changes in active sites, surface reconstruction, absorbates alteration and products formation are directly characterized in a combination with other surface sensitive technologies. The correlation between surface structures and catalytic performance as well as the underlying mechanism can thus be unraveled, which provides insights into the rational design and optimization of catalysts.
Heterogeneous catalysis taking place at solid interfaces plays a crucial role not only in industrial chemical production, energy conversion but also in fundamental research. The dynamic evolution of surface morphology and composition requires full understanding especially under realistic reaction conditions. To this end, conventional scanning tunneling microscopy (STM) has been integrated with high pressure cell and electrochemical cell, forming high pressure (HP) STM and electrochemical (EC) STM for the in-situ/operando characterization at solid-gas and solid-liquid interfaces with atomic resolution, respectively. In this review, we attempt to give a brief introduction to the development and working principle of these two techniques and subsequently summarize several representative progresses in recent days. The dynamic changes in active sites, surface reconstruction, absorbates alteration and products formation are directly characterized in a combination with other surface sensitive technologies. The correlation between surface structures and catalytic performance as well as the underlying mechanism can thus be unraveled, which provides insights into the rational design and optimization of catalysts.
2022, 41(10): 221004
doi: 10.14102/j.cnki.0254-5861.2022-0166
Abstract:
High-resolution magic angle spinning (MAS) NMR can afford both qualitative and quantitative information of the solid, liquid and gas phase at atomic level, and such information obtained at in situ/operando conditions is of vital importance for understanding the crystallization process of material as well as the reaction mechanism of catalysis. To meet the requirement of experimental conditions for material synthesis and catalytic reactions, in situ MAS NMR techniques have been continuously developed for using at higher temperatures and pressures with high sensitivity. Herein, we will briefly outline the development of this technology and discuss its detailed applications in understanding material synthesis and heterogeneous catalysis.
High-resolution magic angle spinning (MAS) NMR can afford both qualitative and quantitative information of the solid, liquid and gas phase at atomic level, and such information obtained at in situ/operando conditions is of vital importance for understanding the crystallization process of material as well as the reaction mechanism of catalysis. To meet the requirement of experimental conditions for material synthesis and catalytic reactions, in situ MAS NMR techniques have been continuously developed for using at higher temperatures and pressures with high sensitivity. Herein, we will briefly outline the development of this technology and discuss its detailed applications in understanding material synthesis and heterogeneous catalysis.
2022, 41(10): 221005
doi: 10.14102/j.cnki.0254-5861.2022-0187
Abstract:
An in-depth understanding of the catalytic reaction mechanism is the key to designing efficient and stable catalysts. In situ transmission electron microscope (TEM) is the most powerful tool to visualize and analyze the microstructures of catalysts during catalysis. In situ TEM combined with three-dimensional (3D) electron tomography (ET) reconstruction technique enables interrogations of catalysts' structural dynamics and chemical changes in high temporal and spatial dimensions. In this review, we discuss and summarize the recent advances in in situ TEM together with 3D ET for catalyst studies. Topics include the latest research progress of in situ TEM imaging as well as 3D visualization and quantitative analysis of catalysts. We also pay particular attention to artificial intelligence (AI)-enhanced smart 3D ET. These include deep learning (DL)-based data compression and storage for the analysis of large TEM data, recovery of wedge-shaped information lost in 3D ET reconstructions, and DL models for reducing residual artifacts in 3D reconstructed images. Finally, the challenges and development prospects of current in situ TEM and 3D ET research are discussed.
An in-depth understanding of the catalytic reaction mechanism is the key to designing efficient and stable catalysts. In situ transmission electron microscope (TEM) is the most powerful tool to visualize and analyze the microstructures of catalysts during catalysis. In situ TEM combined with three-dimensional (3D) electron tomography (ET) reconstruction technique enables interrogations of catalysts' structural dynamics and chemical changes in high temporal and spatial dimensions. In this review, we discuss and summarize the recent advances in in situ TEM together with 3D ET for catalyst studies. Topics include the latest research progress of in situ TEM imaging as well as 3D visualization and quantitative analysis of catalysts. We also pay particular attention to artificial intelligence (AI)-enhanced smart 3D ET. These include deep learning (DL)-based data compression and storage for the analysis of large TEM data, recovery of wedge-shaped information lost in 3D ET reconstructions, and DL models for reducing residual artifacts in 3D reconstructed images. Finally, the challenges and development prospects of current in situ TEM and 3D ET research are discussed.
2022, 41(10): 221007
doi: 10.14102/j.cnki.0254-5861.2022-0134
Abstract:
The roles of temperature change in surface-enhanced Raman scattering (SERS) hotspots are important for understanding the plasmon-mediated selective oxidation of p-aminothiophenol in a SERS measurement. Here, we demonstrate that the temperature change in hotspots seriously influences the conversion of p-aminothiophenol on Au by employing variable-temperature SERS measurements. The conversion steadily and irreversibly increased when the temperature increased from 100 to 360 K. But the conversion decreased above 360 K, because this conversion was exothermic. This temperature-dependence conversion suggests that the temperature change in hotspots originated from the photothermal effect should be coupled to the hot-electron effect in promoting the selective oxidation of p-aminothiophenol.
The roles of temperature change in surface-enhanced Raman scattering (SERS) hotspots are important for understanding the plasmon-mediated selective oxidation of p-aminothiophenol in a SERS measurement. Here, we demonstrate that the temperature change in hotspots seriously influences the conversion of p-aminothiophenol on Au by employing variable-temperature SERS measurements. The conversion steadily and irreversibly increased when the temperature increased from 100 to 360 K. But the conversion decreased above 360 K, because this conversion was exothermic. This temperature-dependence conversion suggests that the temperature change in hotspots originated from the photothermal effect should be coupled to the hot-electron effect in promoting the selective oxidation of p-aminothiophenol.
2022, 41(10): 221008
doi: 10.14102/j.cnki.0254-5861.2022-0133
Abstract:
Understanding the atomic and electronic changes of active sites promotes the whole new sight into electrochemical carbon dioxide reduction reaction (CO2RR), which provides a feasible strategy to achieve carbon neutrality. Here we employ operando high-energy resolution fluorescence-detected X-ray absorption spectroscopy (HERFD-XAS) to track the structural evolution of Ni(II) phthalocyanine (NiPc), considered as the model catalysts with uniform Ni-N4-C8 moiety, during the CO2RR. The HERFD-XAS method is in favor of elucidating the interaction of the reactant/catalyst interface from the atomic electronic structure dimension, facilitating the establishment of the catalytic mechanism and the dynamic structure changes. Based on operando measurement, surface sensitive difference spectra (∆µ) and spectroscopy simulation, the interfacial interactions between the active sites of NiPc and reactants are monitored and the Ni species gradually reduced by increasing the applied potential is discovered. HERFD-XAS method offers an advanced and powerful tool for elucidating the complex catalytic mechanism in further various systems.
Understanding the atomic and electronic changes of active sites promotes the whole new sight into electrochemical carbon dioxide reduction reaction (CO2RR), which provides a feasible strategy to achieve carbon neutrality. Here we employ operando high-energy resolution fluorescence-detected X-ray absorption spectroscopy (HERFD-XAS) to track the structural evolution of Ni(II) phthalocyanine (NiPc), considered as the model catalysts with uniform Ni-N4-C8 moiety, during the CO2RR. The HERFD-XAS method is in favor of elucidating the interaction of the reactant/catalyst interface from the atomic electronic structure dimension, facilitating the establishment of the catalytic mechanism and the dynamic structure changes. Based on operando measurement, surface sensitive difference spectra (∆µ) and spectroscopy simulation, the interfacial interactions between the active sites of NiPc and reactants are monitored and the Ni species gradually reduced by increasing the applied potential is discovered. HERFD-XAS method offers an advanced and powerful tool for elucidating the complex catalytic mechanism in further various systems.
