Mairegger Thomas, Li Haobo, Grießer Christoph, Winkler Daniel, Filser Jakob, Hörmann Nicolas G, Reuter Karsten, Kunze-Liebhäuser Julia
Department of Physical Chemistry, University of Innsbruck, Innrain 52c, Innsbruck 6020, Austria.
School of Chemical Engineering, University of Adelaide, Adelaide 5005, Australia.
ACS Catal. 2023 Apr 13;13(9):5780-5786. doi: 10.1021/acscatal.3c00236. eCollection 2023 May 5.
Transition metal carbides, especially MoC, are praised to be efficient electrocatalysts to reduce CO to valuable hydrocarbons. However, on MoC in an aqueous electrolyte, exclusively the competing hydrogen evolution reaction takes place, and this discrepancy to theory was traced back to the formation of a thin oxide layer at the electrode surface. Here, we study the CO reduction activity at MoC in a non-aqueous electrolyte to avoid such passivation and to determine products and the CO reduction reaction pathway. We find a tendency of CO to reduce to carbon monoxide. This process is inevitably coupled with the decomposition of acetonitrile to a 3-aminocrotonitrile anion. Furthermore, a unique behavior of the non-aqueous acetonitrile electrolyte is found, where the electrolyte, instead of the electrocatalyst, governs the catalytic selectivity of the CO reduction. This is evidenced by in situ electrochemical infrared spectroscopy on different electrocatalysts as well as by density functional theory calculations.
过渡金属碳化物，尤其是碳化钼，被誉为将一氧化碳还原为有价值碳氢化合物的高效电催化剂。然而，在水性电解质中的碳化钼上，仅发生竞争性析氢反应，这种与理论的差异可追溯到电极表面形成的薄氧化层。在此，我们研究了非水性电解质中碳化钼的一氧化碳还原活性，以避免此类钝化现象，并确定产物和一氧化碳还原反应途径。我们发现一氧化碳有还原为一氧化碳的趋势。此过程不可避免地伴随着乙腈分解为3-氨基巴豆腈阴离子。此外，还发现了非水性乙腈电解质的独特行为，即电解质而非电催化剂决定了一氧化碳还原的催化选择性。这通过对不同电催化剂的原位电化学红外光谱以及密度泛函理论计算得到了证实。
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