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2022 Volume 41 Issue 7
2022, 41(7): 220700
doi: 10.14102/j.cnki.0254-5861.2022-0160
Abstract:
2022, 41(7): 220700
doi: 10.14102/j.cnki.0254-5861.2022-0165
Abstract:
Rational design of Fe and N co-doped carbon catalysts (Fe-NCs), one promising non-precious cathode catalyst, is critical to commercialization of proton exchange membrane fuel cells. The atomic Fe site density of Fe-NCs is critical to improve catalytic currents approaching industrial levels. One recent research proposes a template-guided strategy to break the limit of Fe site density, and greatly promotes the fuel cell performance.
Rational design of Fe and N co-doped carbon catalysts (Fe-NCs), one promising non-precious cathode catalyst, is critical to commercialization of proton exchange membrane fuel cells. The atomic Fe site density of Fe-NCs is critical to improve catalytic currents approaching industrial levels. One recent research proposes a template-guided strategy to break the limit of Fe site density, and greatly promotes the fuel cell performance.
2022, 41(7): 220700
doi: 10.14102/j.cnki.0254-5861.2022-0036
Abstract:
With the increasing demand for energy, various emerging energy storage/conversion technologies have gradually penetrated human life, providing numerous conveniences. The practical application efficiency is often affected by the slow kinetics of hydrogen or oxygen electrocatalytic reactions (hydrogen evolution and oxidation reactions, oxygen evolution and reduction reactions) among the emerging devices. Therefore, the researchers devote to finding cost-effective electrocatalysts. Non-noble metal catalysts have low cost and good catalytic activity, but poor stability, agglomeration, dissolution, and other problems will occur after a long cycle, such as transition metal oxides and carbides. Transition metal nitrides (TMNs) stand out among all kinds of non-noble metal catalysts because of the intrinsic platinum-like electrocatalytic activities, relatively high conductivity, and wide range of tunability. In this review, the applications of TMNs in electrocatalytic fields are summarized based on the number of metals contained in TMNs. The practical application potentials of TMNs in fuel cell, water splitting, zinc-air battery and other electrochemical energy storage/conversion devices are also listed. Finally, the design strategies and viewpoints of TMNs-based electrocatalyst are summarized. The potential challenges of TMNs-based electrocatalyst in the development of electrocatalytic energy devices in the future are prospected.
With the increasing demand for energy, various emerging energy storage/conversion technologies have gradually penetrated human life, providing numerous conveniences. The practical application efficiency is often affected by the slow kinetics of hydrogen or oxygen electrocatalytic reactions (hydrogen evolution and oxidation reactions, oxygen evolution and reduction reactions) among the emerging devices. Therefore, the researchers devote to finding cost-effective electrocatalysts. Non-noble metal catalysts have low cost and good catalytic activity, but poor stability, agglomeration, dissolution, and other problems will occur after a long cycle, such as transition metal oxides and carbides. Transition metal nitrides (TMNs) stand out among all kinds of non-noble metal catalysts because of the intrinsic platinum-like electrocatalytic activities, relatively high conductivity, and wide range of tunability. In this review, the applications of TMNs in electrocatalytic fields are summarized based on the number of metals contained in TMNs. The practical application potentials of TMNs in fuel cell, water splitting, zinc-air battery and other electrochemical energy storage/conversion devices are also listed. Finally, the design strategies and viewpoints of TMNs-based electrocatalyst are summarized. The potential challenges of TMNs-based electrocatalyst in the development of electrocatalytic energy devices in the future are prospected.
2022, 41(7): 220701
doi: 10.14102/j.cnki.0254-5861.2022-0098
Abstract:
Platinum-Ruthenium (PtRu)-based materials are considered the "holy grail" of electrocatalysts for methanol oxidation reaction (MOR) in the fuel cells technique. However, to the best of our knowledge, the exhaustive review report on the advance of PtRu materials for methanol oxidation is rarely summarized for the recent novel achievements. Herein, we summarize and discuss the latest progress of PtRu-based catalysts in MOR. The reaction mechanism of MOR is firstly introduced, and the promotion mechanism is revealed by the relevant activity descriptor, the in-situ spectroscopic analysis and the theoretical calculation. Subsequently, some advanced regulation strategies of PtRu-based catalysts are concluded, including support engineering, morphology design and surface interface regulation. Finally, the challenges and opportunities to improve the MOR performance of PtRu-based electrocatalysts are prospected to further promote the widespread application of PtRu-based catalysts in electrocatalytic systems. It is concluded that many efforts are still required to decipher the atomic scale structure-activity relationship and the structural changes of atoms and electrons in the reaction process by advanced strategies and characterization methods. Hopefully, this review can be helpful for novel PtRu-based catalyst development and understanding their correlation to the structure and performance of energy-relevant electrocatalysis.
Platinum-Ruthenium (PtRu)-based materials are considered the "holy grail" of electrocatalysts for methanol oxidation reaction (MOR) in the fuel cells technique. However, to the best of our knowledge, the exhaustive review report on the advance of PtRu materials for methanol oxidation is rarely summarized for the recent novel achievements. Herein, we summarize and discuss the latest progress of PtRu-based catalysts in MOR. The reaction mechanism of MOR is firstly introduced, and the promotion mechanism is revealed by the relevant activity descriptor, the in-situ spectroscopic analysis and the theoretical calculation. Subsequently, some advanced regulation strategies of PtRu-based catalysts are concluded, including support engineering, morphology design and surface interface regulation. Finally, the challenges and opportunities to improve the MOR performance of PtRu-based electrocatalysts are prospected to further promote the widespread application of PtRu-based catalysts in electrocatalytic systems. It is concluded that many efforts are still required to decipher the atomic scale structure-activity relationship and the structural changes of atoms and electrons in the reaction process by advanced strategies and characterization methods. Hopefully, this review can be helpful for novel PtRu-based catalyst development and understanding their correlation to the structure and performance of energy-relevant electrocatalysis.
2022, 41(7): 220703
doi: 10.14102/j.cnki.0254-5861.2022-0095
Abstract:
Nickel (Ni)-based materials are promising electrocatalysts for the urea electrooxidation reaction, as the in situ formed NiOOH species on their surface during operation are catalytically active sites. In this work, phytate-coordinated Ni foam (PA-NF) is shown to deliver a high catalytic performance, with a potential as low as 1.38 V at 10 mA/cm2, a Tafel slope as low as 64.1 mV/dec, and superior catalytic stability. Characterizations revealed that such a high performance was ascribed to the kinetic acceleration of surface reconstruction and the enriched NiOOH active species on the PA-NF surface owing to PA-coordination induced upshift of d-band center of Ni sites. Overall, a novel and simple strategy is provided for designing the efficient as well as universal Ni-based catalyst for the electrooxidation of urea, which can also be extended to other transition-metal-based systems.
Nickel (Ni)-based materials are promising electrocatalysts for the urea electrooxidation reaction, as the in situ formed NiOOH species on their surface during operation are catalytically active sites. In this work, phytate-coordinated Ni foam (PA-NF) is shown to deliver a high catalytic performance, with a potential as low as 1.38 V at 10 mA/cm2, a Tafel slope as low as 64.1 mV/dec, and superior catalytic stability. Characterizations revealed that such a high performance was ascribed to the kinetic acceleration of surface reconstruction and the enriched NiOOH active species on the PA-NF surface owing to PA-coordination induced upshift of d-band center of Ni sites. Overall, a novel and simple strategy is provided for designing the efficient as well as universal Ni-based catalyst for the electrooxidation of urea, which can also be extended to other transition-metal-based systems.
2022, 41(7): 220704
doi: 10.14102/j.cnki.0254-5861.2022-0144
Abstract:
Developing efficient and durable electrocatalysts for water splitting, which has long been regarded as one of the most promising patterns to produce green hydrogen, is of great significance but still challenging. Herein, ample Co/MoN heterogeneous domains/nitrogen-doped carbon (Co/MoN/NC) nanosheet arrays as high-performance hydrogen evolution reaction (HER) electrocatalyst via a typical nitriding-carbonization strategy are successfully prepared on nickel foam (NF), which exhibits a low overpotential of 29 mV at 10 mA cm-2, together with excellent durability at 20 mA cm-2 for 90 h in alkaline solution. Such excellent catalytic property for HER can be attributed to the generation of abundant Co/MoN heterogeneous structures. Additionally, the high conductivity of Co/MoN and NC also increases the charge transfer rate, further helping accelerate the reaction rate of HER. This work presents an efficient method for improving the catalytic hydrogen evolution activity in basic solution.
Developing efficient and durable electrocatalysts for water splitting, which has long been regarded as one of the most promising patterns to produce green hydrogen, is of great significance but still challenging. Herein, ample Co/MoN heterogeneous domains/nitrogen-doped carbon (Co/MoN/NC) nanosheet arrays as high-performance hydrogen evolution reaction (HER) electrocatalyst via a typical nitriding-carbonization strategy are successfully prepared on nickel foam (NF), which exhibits a low overpotential of 29 mV at 10 mA cm-2, together with excellent durability at 20 mA cm-2 for 90 h in alkaline solution. Such excellent catalytic property for HER can be attributed to the generation of abundant Co/MoN heterogeneous structures. Additionally, the high conductivity of Co/MoN and NC also increases the charge transfer rate, further helping accelerate the reaction rate of HER. This work presents an efficient method for improving the catalytic hydrogen evolution activity in basic solution.
2022, 41(7): 220704
doi: 10.14102/j.cnki.0254-5861.2022-0057
Abstract:
The porphyrin-based MOFs formed by combining Zr6 clusters and porphyrin carboxylic acids with clear M-N4 active centers show unique advantages in electrocatalytic reduction of CO2 (CO2RR). However, its conductivity is still the bottleneck that limits its catalytic activity due to the electrical insulation of the Zr cluster. Therefore, the porphyrin-based MOFs of PCN-222(M) (M = Mn, Co, Ni, Zn) with explicit M-N4 coordination were combined with the highly conductive material carbon nanotube (CNT) for discussing the influence of metal centers on the CO2RR performance based on theoretical calculations and experimental observations. The results show that the PCN-222(Mn)/CNT, PCN-222(Co)/CNT, and PCN-222(Zn)/CNT all exhibit high selectivity to CO (FECO > 80%) in the range of -0.60 to -0.70 V vs. RHE. The FECOmax of PCN-222(Mn)/CNT (-0.60 V vs. RHE), PCN-222(Co)/CNT (-0.65 V vs. RHE), and PCN-222(Zn)/CNT (-0.70 V vs. RHE) are 88.5%, 89.3% and 92.5%, respectively. The high catalytic activity of PCN-222(Mn)/CNT and PCN-222(Co)/CNT comes from the excellent electron mobility of their porphyrin rings and their low ΔG*COOH (0.87 and 0.58 eV). It reveals that the strength of backbonding π of the transition metal and its influence on the electron mobility in the porphyrin ring can affect its CO2RR activity.
The porphyrin-based MOFs formed by combining Zr6 clusters and porphyrin carboxylic acids with clear M-N4 active centers show unique advantages in electrocatalytic reduction of CO2 (CO2RR). However, its conductivity is still the bottleneck that limits its catalytic activity due to the electrical insulation of the Zr cluster. Therefore, the porphyrin-based MOFs of PCN-222(M) (M = Mn, Co, Ni, Zn) with explicit M-N4 coordination were combined with the highly conductive material carbon nanotube (CNT) for discussing the influence of metal centers on the CO2RR performance based on theoretical calculations and experimental observations. The results show that the PCN-222(Mn)/CNT, PCN-222(Co)/CNT, and PCN-222(Zn)/CNT all exhibit high selectivity to CO (FECO > 80%) in the range of -0.60 to -0.70 V vs. RHE. The FECOmax of PCN-222(Mn)/CNT (-0.60 V vs. RHE), PCN-222(Co)/CNT (-0.65 V vs. RHE), and PCN-222(Zn)/CNT (-0.70 V vs. RHE) are 88.5%, 89.3% and 92.5%, respectively. The high catalytic activity of PCN-222(Mn)/CNT and PCN-222(Co)/CNT comes from the excellent electron mobility of their porphyrin rings and their low ΔG*COOH (0.87 and 0.58 eV). It reveals that the strength of backbonding π of the transition metal and its influence on the electron mobility in the porphyrin ring can affect its CO2RR activity.
2022, 41(7): 220705
doi: 10.14102/j.cnki.0254-5861.2022-0102
Abstract:
The heterojunction interfacial modulation of FeP is an effective strategy to regulate the intrinsic activity and stability, which is a major challenge to promote the industrial application of FeP-based electrocatalysts. Herein, hollow Fe4C/FeP box with heterojunction interface and carbon armor is successfully synthesized, which can expose numerous active sites and protect catalyst from corrosion. Electrochemical measurements show that Fe4C/FeP exhibits excellent hydrogen evolution activity and stability. It only needs 180 mV to achieve the current density of 10 mA cm-2. The high-activity may be due to the synergistic effects of porous framework, graphitic carbon coating and heterojunction structure of Fe4C and FeP, which optimize the electronic structure and accelerates electron transfer. In addition, the target catalyst can withstand 5000 cycles of CV testing without significant change in properties. The excellent stability may be attributed to the graphitic carbon coating as the armor that can prevent the catalyst from corrosion of electrolyte. This work may provide a synthetic approach to produce a series of carbon-coated and heterojunction structure of transition metal phosphides for water splitting.
The heterojunction interfacial modulation of FeP is an effective strategy to regulate the intrinsic activity and stability, which is a major challenge to promote the industrial application of FeP-based electrocatalysts. Herein, hollow Fe4C/FeP box with heterojunction interface and carbon armor is successfully synthesized, which can expose numerous active sites and protect catalyst from corrosion. Electrochemical measurements show that Fe4C/FeP exhibits excellent hydrogen evolution activity and stability. It only needs 180 mV to achieve the current density of 10 mA cm-2. The high-activity may be due to the synergistic effects of porous framework, graphitic carbon coating and heterojunction structure of Fe4C and FeP, which optimize the electronic structure and accelerates electron transfer. In addition, the target catalyst can withstand 5000 cycles of CV testing without significant change in properties. The excellent stability may be attributed to the graphitic carbon coating as the armor that can prevent the catalyst from corrosion of electrolyte. This work may provide a synthetic approach to produce a series of carbon-coated and heterojunction structure of transition metal phosphides for water splitting.
2022, 41(7): 220705
doi: 10.14102/j.cnki.0254-5861.2022-0104
Abstract:
Insufficient activity and instability (poisoning) of Pt-based electrocatalysts for methanol oxidation and oxygen reduction reactions (MOR/ORR) impede the development of direct methanol fuel cells. Here, CoWO4 nanoparticles-loaded WO3 microrods coated by a thin carbon-layer are used as Pt-supports/co-catalysts for MOR/ORR. WO3 grows along the (110) crystal plane to form microrod (diameter of ~0.6 um), which is coated by a carbon-layer (~5 nm). Pt-CoWO4/WO3@NCL-mr (850 ℃) shows a higher mass activity (2208 mA mgpt-1) than the commercial Pt/C (659.4 mA mgpt-1). CoWO4/WO3 heterojunction on the microrod surface with abundant oxygen vacancies allows the generation of surface-adsorbed hydroxyl to facilitate CO elimination and regeneration of the occupied Pt active-sites (promising stability). Pt-CoWO4/WO3@NCL-mr (850 ℃) has higher half-wave (0.46 V) and onset (0.54 V) potentials than Pt/C (0.41 and 0.50 V) for ORR. The microrod structure of CoWO4/WO3@NCL facilitates the dispersibility of Pt NPs to increase the utilization of Pt active sites and relieve the self-aggregation of Pt to obtain a promising synergy between Pt and CoWO4 (Co2+) for ORR in acid media. This study provides insights not only into the synthesis of acid-resistant WO3@NCL microrod as active Pt co-catalyst, but also into the effective utilization of surface oxygen vacancies and Co2+ for MOR/ORR.
Insufficient activity and instability (poisoning) of Pt-based electrocatalysts for methanol oxidation and oxygen reduction reactions (MOR/ORR) impede the development of direct methanol fuel cells. Here, CoWO4 nanoparticles-loaded WO3 microrods coated by a thin carbon-layer are used as Pt-supports/co-catalysts for MOR/ORR. WO3 grows along the (110) crystal plane to form microrod (diameter of ~0.6 um), which is coated by a carbon-layer (~5 nm). Pt-CoWO4/WO3@NCL-mr (850 ℃) shows a higher mass activity (2208 mA mgpt-1) than the commercial Pt/C (659.4 mA mgpt-1). CoWO4/WO3 heterojunction on the microrod surface with abundant oxygen vacancies allows the generation of surface-adsorbed hydroxyl to facilitate CO elimination and regeneration of the occupied Pt active-sites (promising stability). Pt-CoWO4/WO3@NCL-mr (850 ℃) has higher half-wave (0.46 V) and onset (0.54 V) potentials than Pt/C (0.41 and 0.50 V) for ORR. The microrod structure of CoWO4/WO3@NCL facilitates the dispersibility of Pt NPs to increase the utilization of Pt active sites and relieve the self-aggregation of Pt to obtain a promising synergy between Pt and CoWO4 (Co2+) for ORR in acid media. This study provides insights not only into the synthesis of acid-resistant WO3@NCL microrod as active Pt co-catalyst, but also into the effective utilization of surface oxygen vacancies and Co2+ for MOR/ORR.
2022, 41(7): 220706
doi: 10.14102/j.cnki.0254-5861.2022-0110
Abstract:
Rational design of highly efficient and durable electrocatalysts with low cost to replace noble-metal based catalysts for seawater electrolysis is extremely desirable, but challenging. In this work, we demonstrate a rapid electrodeposition method by growing P-Ni4Mo on the surface of the copper foam (CF) substrate to synthesize an efficient seawater electrolysis catalyst (P-Ni4Mo/CF). The catalyst exhibited considerable HER performance and stability in alkaline seawater, with the overpotential as low as 260 mV at a current density of 100 mA cm-2. The P-Ni4Mo/CF is capable of achieving 1.0 A cm-2 with an overpotential of 551 mV, which is slightly worse than that of the Pt/C catalyst (453 mV). Moreover, P-Ni4Mo/CF demonstrates robust durability, with almost no activity loss after the durability test for more than 200 h. This work not only reports a new catalyst for seawater electrolysis, but also presents a strategy for the performance enhancement of seawater electrolysis.
Rational design of highly efficient and durable electrocatalysts with low cost to replace noble-metal based catalysts for seawater electrolysis is extremely desirable, but challenging. In this work, we demonstrate a rapid electrodeposition method by growing P-Ni4Mo on the surface of the copper foam (CF) substrate to synthesize an efficient seawater electrolysis catalyst (P-Ni4Mo/CF). The catalyst exhibited considerable HER performance and stability in alkaline seawater, with the overpotential as low as 260 mV at a current density of 100 mA cm-2. The P-Ni4Mo/CF is capable of achieving 1.0 A cm-2 with an overpotential of 551 mV, which is slightly worse than that of the Pt/C catalyst (453 mV). Moreover, P-Ni4Mo/CF demonstrates robust durability, with almost no activity loss after the durability test for more than 200 h. This work not only reports a new catalyst for seawater electrolysis, but also presents a strategy for the performance enhancement of seawater electrolysis.
2022, 41(7): 220707
doi: 10.14102/j.cnki.0254-5861.2022-0145
Abstract:
Developing highly efficient, easy-to-make and cost-effective bifunctional electrocatalysts for water splitting with lower cell voltages is crucial to producing massive hydrogen fuel. In response, the coupled hierarchical Ni/Fe-based MOF nanosheet arrays with embedded metal sulfide nanoclusters onto nickel foam skeleton (denoted as Fe-Ni3S2 @NiFe-MOF/NF) are fabricated, in which the Fe-Ni3S2 clusters could effectively restrain the aggregation of the layer metal-organic frameworks (MOF) nanosheets and adjust the local electronic structures of MOFs nanosheets. Benefiting from the rapid charge transfer and the exposure of abundant active sites, the well-designed Fe-Ni3S2@NiFe-MOF/NF displays excellent oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) performance. More importantly, when equipped in the alkaline water electrolyzer, the Fe-Ni3S2@NiFe-MOF/NF enables the system with a mere 1.6 V for achieving the current density of 10 mA cm-2. This work offers a paradigm for designing efficient bifunctional HER/OER electrocatalysts based on the hybrid materials of nanostructured metal sulfide and MOF.
Developing highly efficient, easy-to-make and cost-effective bifunctional electrocatalysts for water splitting with lower cell voltages is crucial to producing massive hydrogen fuel. In response, the coupled hierarchical Ni/Fe-based MOF nanosheet arrays with embedded metal sulfide nanoclusters onto nickel foam skeleton (denoted as Fe-Ni3S2 @NiFe-MOF/NF) are fabricated, in which the Fe-Ni3S2 clusters could effectively restrain the aggregation of the layer metal-organic frameworks (MOF) nanosheets and adjust the local electronic structures of MOFs nanosheets. Benefiting from the rapid charge transfer and the exposure of abundant active sites, the well-designed Fe-Ni3S2@NiFe-MOF/NF displays excellent oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) performance. More importantly, when equipped in the alkaline water electrolyzer, the Fe-Ni3S2@NiFe-MOF/NF enables the system with a mere 1.6 V for achieving the current density of 10 mA cm-2. This work offers a paradigm for designing efficient bifunctional HER/OER electrocatalysts based on the hybrid materials of nanostructured metal sulfide and MOF.
