期刊
PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
卷 115, 期 50, 页码 12686-12691出版社
NATL ACAD SCIENCES
DOI: 10.1073/pnas.1811396115
关键词
electrocatalysis; CO2 reduction; solar fuel; formate production; hydride
资金
- US Department of Energy, Office of Science, Office of Basic Energy Sciences [DE-SC0012150]
- National Science Foundation Graduate Research Fellowship [DGE 1321846]
- Sloan Foundation
- Canadian Institute for Advanced Research (CIFAR) Azrieli Global Scholar in the BioInspired Solar Energy Program
- U.S. Department of Energy (DOE) [DE-SC0012150] Funding Source: U.S. Department of Energy (DOE)
A critical challenge in electrocatalytic CO2 reduction to renewable fuels is product selectivity. Desirable products of CO2 reduction require proton equivalents, but key catalytic intermediates can also be competent for direct proton reduction to H-2. Understanding how to manage divergent reaction pathways at these shared intermediates is essential to achieving high selectivity. Both proton reduction to hydrogen and CO2 reduction to formate generally proceed through a metal hydride intermediate. We apply thermodynamic relationships that describe the reactivity of metal hydrides with H+ and CO2 to generate a thermodynamic product diagram, which outlines the free energy of product formation as a function of proton activity and hydricity (Delta G(H-)), or hydride donor strength. The diagram outlines a region of metal hydricity and proton activity in which CO2 reduction is favorable and H+ reduction is suppressed. We apply our diagram to inform our selection of [Pt(dmpe)(2)](PF6)(2) as a potential catalyst, because the corresponding hydride [HPt(dmpe)(2)](+) has the correct hydricity to access the region where selective CO2 reduction is possible. We validate our choice experimentally; [Pt(dmpe)(2)](PF6)(2) is a highly selective electrocatalyst for CO2 reduction to formate (> 90% Faradaic efficiency) at an overpotential of less than 100 mV in acetonitrile with no evidence of catalyst degradation after electrolysis. Our report of a selective catalyst for CO2 reduction illustrates how our thermodynamic diagrams can guide selective and efficient catalyst discovery.
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