The optimization of traditional electrocatalysts has reached a point where progress is impeded by fundamental physical factors including inherent scaling relations among thermokinetic characteristics of different elementary reaction steps, non‐Nernstian behavior, and electronic structure of the catalyst. This indicates that the currently utilized classes of electrocatalysts may not be adequate for future needs. This study reports on synthesis and characterization of a new class of materials based on 2D transition metal dichalcogenides including sulfides, selenides, and tellurides of group V and VI transition metals that exhibit excellent catalytic performance for both oxygen reduction and evolution reactions in an aprotic medium with Li salts. The reaction rates are much higher for these materials than previously reported catalysts for these reactions. The reasons for the high activity are found to be the metal edges with adiabatic electron transfer capability and a cocatalyst effect involving an ionic‐liquid electrolyte. These new materials are expected to have high activity for other core electrocatalytic reactions and open the way for advances in energy storage and catalysis.
The conversion and utilization of carbon dioxide (CO2) have dual significance for reducing carbon emissions and solving energy demand. Catalytic reduction of CO2 is a promising way to convert and utilize CO2. However, high-performance catalysts with excellent catalytic activity, selectivity and stability are currently lacking. High-throughput methods offer an effective way to screen high-performance CO2 reduction catalysts. Here, recent advances in high-throughput screening of electrocatalysts for CO2 reduction are reviewed. First, the mechanism of CO2 reduction reaction by electrocatalysis and potential catalyst candidates are introduced. Second, high-throughput computational methods developed to accelerate catalyst screening are presented, such as density functional theory and machine learning. Then, high-throughput experimental methods are outlined, including experimental design, high-throughput synthesis, in situ characterization and high-throughput testing. Finally, future directions of high-throughput screening of CO2 reduction electrocatalysts are outlooked. This review will be a valuable reference for future research on high-throughput screening of CO2 electrocatalysts.
more » « less- Award ID(s):
- 2011754
- NSF-PAR ID:
- 10500610
- Publisher / Repository:
- IEEE
- Date Published:
- Journal Name:
- Energies
- Volume:
- 15
- Issue:
- 18
- ISSN:
- 1996-1073
- Page Range / eLocation ID:
- 6666
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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Abstract Direct conversion of CO2into carbon‐neutral fuels or industrial chemicals holds a great promise for renewable energy storage and mitigation of greenhouse gas emission. However, experimentally finding an electrocatalyst for specific final products with high efficiency and high selectivity poses serious challenges due to multiple electron transfer, complicated intermediates, and numerous reaction pathways in electrocatalytic CO2reduction. Here, an intrinsic descriptor that correlates the catalytic activity with the topological, bonding, and electronic structures of catalytic centers on M–N–C based single‐atom catalysts is discovered. The “volcano”‐shaped relationships between the descriptor and catalytic activity are established from which the best single‐atom catalysts for CO2reduction are found. Moreover, the reaction mechanisms, intermediates, reaction pathways, and final products can also be distinguished by this new descriptor. The descriptor can also be used to predict the activity of the single‐atom catalysts for electrochemical reactions such as hydrogen evolution, oxygen reduction and evolution reactions in fuel cells and water‐splitting. These predictions are confirmed by the experimental results for onset potential and Faraday efficiency. The design principles derived from the descriptors open a door for rational design and rapid screening of highly efficient electrocatalysts for CO2conversion as well as other electrochemical energy systems.
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The optimization of traditional electrocatalysts has reached a point where progress is impeded by fundamental physical factors including inherent scaling relations among thermokinetic characteristics of different elementary reaction steps, non‐Nernstian behavior, and electronic structure of the catalyst. This indicates that the currently utilized classes of electrocatalysts may not be adequate for future needs. This study reports on synthesis and characterization of a new class of materials based on 2D transition metal dichalcogenides including sulfides, selenides, and tellurides of group V and VI transition metals that exhibit excellent catalytic performance for both oxygen reduction and evolution reactions in an aprotic medium with Li salts. The reaction rates are much higher for these materials than previously reported catalysts for these reactions. The reasons for the high activity are found to be the metal edges with adiabatic electron transfer capability and a cocatalyst effect involving an ionic‐liquid electrolyte. These new materials are expected to have high activity for other core electrocatalytic reactions and open the way for advances in energy storage and catalysis.more » « less
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Abstract Bifunctional oxygen catalysts for oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) with high activities and low‐cost are of prime importance and challenging in the development of fuel cells and rechargeable metal–air batteries. This study reports a porous carbon nanomaterial loaded with cobalt nanoparticles (Co@NC‐
x /y ) derived from pyrolysis of a Co/Zn bimetallic zeolitic imidazolite framework, which exhibits incredibly high activity as bifunctional oxygen catalysts. For instance, the optimal catalyst of Co@NC‐3/1 has the interconnected framework structure between porous carbon and embedded carbon nanotubes, which shows the superb ORR activity with onset potential of ≈1.15 V and half‐wave potential of ≈0.93 V. Moreover, it presents high OER activity that can be further enhanced to over commercial RuO2by P‐doped with overpotentials of 1.57 V versus reversible hydrogen electrode at 10 mA cm−2and long‐term stability for 2000 circles and a Tafel slope of 85 mV dec−1. Significantly, the nanomaterial demonstrates better catalytic performance and durability than Pt/C for ORR and commercial RuO2and IrO2for OER. These findings suggest the importance of a synergistic effect of graphitic carbon, nanotubes, exposed Co–Nx active sites, and interconnected framework structure of various carbons for bifunctional oxygen electrocatalysts. -
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Abstract It is essential but still challenging to design and construct inexpensive, highly active bifunctional oxygen electrocatalysts for the development of high power density zinc–air batteries (ZABs). Herein, a CoFe‐S@3D‐S‐NCNT electrocatalyst with a 3D hierarchical structure of carbon nanotubes growing on leaf‐like carbon microplates is designed and prepared through chemical vapour deposition pyrolysis of CoFe‐MOF and subsequent hydrothermal sulfurization. Its 3D hierarchical structure shows excellent hydrophobicity, which facilitates the diffusion of oxygen and thus accelerates the oxygen reduction reaction (ORR) kinetic process. Alloying and sulfurization strategies obviously enrich the catalytic species in the catalyst, including cobalt or cobalt ferroalloy sulfides, their heterojunction, core–shell structure, and S, N‐doped carbon, which simultaneously improve the ORR/OER catalytic activity with a small potential gap (Δ
E = 0.71 V). Benefiting from these characteristics, the corresponding liquid ZABs show high peak power density (223 mW cm−2), superior specific capacity (815 mA h gZn−1), and excellent stability at 5 mA cm−2for ≈900 h. The quasi‐solid‐state ZABs also exhibit a very high peak power density of 490 mW cm−2and an excellent voltage round‐trip efficiency of more than 64%. This work highlights that simultaneous composition optimization and microstructure design of catalysts can effectively improve the performance of ZABs.
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Accepted Manuscript1.0
- Journal Article:
- https://doi.org/10.3390/en15186666
