Inhibiting the Hydrogen Evolution Reaction (HER) with Proximal Cations: A Strategy for Promoting Selective Electrocatalytic Reduction
Inhibiting the Hydrogen Evolution Reaction (HER) with Proximal Cations: A Strategy for Promoting Selective Electrocatalytic Reduction
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DOI：
10.1021/acscatal.1c01527
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发表时间：
2021-06-18
期刊：
影响因子：
12.9
通讯作者：
Yang, Jenny Y.
中科院分区：
文献类型：
--
作者：
Barlow, Jeffrey M.;Ziller, Joseph W.;Yang, Jenny Y.
大多数电化学还原反应需要质子；然而，质子直接还原为氢是一种常见的竞争性副反应，会降低所需产物的总产率（法拉第效率）。据报道，固定的近端单双或双双离子可抑制析氢反应 (HER)。合成了带有氮杂冠官能团的 SNS 三齿配体以及相应的 Pd(II) 和 Rh(I) 配合物。对于 Pd 配合物，与缺乏氮杂冠的同类物相比，氮杂冠中 Na+ 或 Ba2+ 离子的存在可将析氢过电势提高高达 260 mV。在乙腈和二甲基甲酰胺中使用阳离子酸和中性酸观察到 HER 过电势的增加。此外，对于 Pd 配合物，在氮杂冠中包含 Ba2+ 离子适度提高了电催化 CO2 还原为 CO 的选择性，而 H-2 是缺乏氮杂冠的同类物的唯一产物。含 Ba2+ 的配合物也具有改善的催化稳定性，尽管所有配合物最终在长时间的电解条件下都不稳定。通过安装局部电荷来增加 HER 过电势，例证了抑制析氢反应的有效催化剂设计策略。
Most electrochemical reduction reactions require protons; however, direct reduction of protons to hydrogen is a common competitive side reaction that lowers the overall yield (Faradaic efficiency) for the desired product. Inhibition of the hydrogen evolution reaction (HER) by fixed, proximal mono- or dication is reported. An SNS tridentate ligand with a pendant azacrown functionality and the corresponding Pd(II) and Rh(I) complexes were synthesized. For the Pd complexes, the presence of a Na+ or Ba2+ ion in the aza-crown increases the overpotential for hydrogen evolution by up to 260 mV compared to a congener that lacks an aza-crown. The increase in the overpotential for HER was observed with cationic and neutral acids in both acetonitrile and dimethylformamide. Additionally, for the Pd complexes, the inclusion of a Ba2+ ion into the aza-crown modestly improved the selectivity for electrocatalytic CO2 reduction to CO, whereas H-2 was the only product for the congener lacking the aza-crown. The Ba2+-containing complex also had improved catalytic stability, although all complexes were ultimately unstable under prolonged electrolytic conditions. The increase in the overpotential for HER through the installation of a local charge exemplifies an effective catalyst design strategy for inhibiting the hydrogen evolution reaction.