期刊
JOURNAL OF THE AMERICAN CHEMICAL SOCIETY
卷 141, 期 31, 页码 12372-12381出版社
AMER CHEMICAL SOC
DOI: 10.1021/jacs.9b05576
关键词
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资金
- FCH Joint Undertaking (CRESCENDO project) [779366]
- German Ministry of Economics and Energy (BMWi) through project ChemEFlex [FKN 0350013A]
- China Scholarship Council (CSC)
- CRESCENDO project
- Carlsberg Foundation [CF15-0165]
- Innovation Fund Denmark [5160-00003B]
Nitrogen-doped carbon materials featuring atomically dispersed metal cations (M-N-C) are an emerging family of materials with potential applications for electrocatalysis. The electrocatalytic activity of M-N-C materials toward four-electron oxygen reduction reaction (ORR) to H2O is a mainstream line of research for replacing platinum-group-metal-based catalysts at the cathode of fuel cells. However, fundamental and practical aspects of their electrocatalytic activity toward two-electron ORR to H2O2, a future green dream process for chemical industry, remain poorly understood. Here we combined computational and experimental efforts to uncover the trends in electrochemical H2O2 production over a series of M-N-C materials (M = Mn, Fe, Co, Ni, and Cu) exclusively comprising atomically dispersed M-N x sites from molecular first-principles to bench-scale electrolyzers operating at industrial current density. We investigated the effect of the nature of a 3d metal within a series of M-N-C catalysts on the electrocatalytic activity/selectivity for ORR (H2O2 and H2O products) and H2O2 reduction reaction (H2O2 RR). Co-N-C catalyst was uncovered with outstanding H2O2 productivity considering its high ORR. activity, highest H2O2 selectivity, and lowest H2O2 RR activity. The activity-selectivity trend over M-N-C materials was further analyzed by density functional theory, providing molecular-scale understandings of experimental volcano trends for four- and two-electron ORR. The predicted binding energy of HO* intermediate over Co-N-C catalyst is located near the top of the volcano accounting for favorable two-electron ORR The industrial H2O2 productivity over Co-N-C catalyst was demonstrated in a microflow cell, exhibiting an unprecedented production rate of more than 4 mol peroxide g(catalyst)(-1) h(-1) at a current density of 50 mA cm(-2).
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