Department of Chemistry, University of Cincinnati, Cincinnati, OH, 45221, USA.
Department of Chemistry, University of California Riverside, Riverside, CA, 92521, USA.
Nat Commun. 2023 Jan 31;14(1):525. doi: 10.1038/s41467-023-36142-7.
The broad employment of water electrolysis for hydrogen (H) production is restricted by its large voltage requirement and low energy conversion efficiency because of the sluggish oxygen evolution reaction (OER). Herein, we report a strategy to replace OER with a thermodynamically more favorable reaction, the partial oxidation of formaldehyde to formate under alkaline conditions, using a CuAg electrocatalyst. Such a strategy not only produces more valuable anodic product than O but also releases H at the anode with a small voltage input. Density functional theory studies indicate the HC(OH)O intermediate from formaldehyde hydration can be better stabilized on CuAg than on Cu or Ag, leading to a lower C-H cleavage barrier. A two-electrode electrolyzer employing an electrocatalyst of CuAg(+)||NiN/Ni(-) can produce H at both anode and cathode simultaneously with an apparent 200% Faradaic efficiency, reaching a current density of 500 mA/cm with a cell voltage of only 0.60 V.
水的电解广泛用于氢气（H）的生产，但由于氧气析出反应（OER）缓慢，需要较大的电压和较低的能量转换效率，从而受到限制。在此，我们报告了一种策略，即在碱性条件下，用热力学上更有利的反应——甲醛的部分氧化来替代 OER，生成甲酸盐，使用的是 CuAg 电催化剂。这种策略不仅产生比 OER 更有价值的阳极产物，而且在阳极以较小的电压输入释放 H。密度泛函理论研究表明，甲醛水合生成的 HC(OH)O 中间体在 CuAg 上比在 Cu 或 Ag 上更稳定，导致 C-H 断裂的势垒更低。采用 CuAg(+)||NiN/Ni(-)电催化剂的两电极电解槽可以同时在阳极和阴极产生 H，表观法拉第效率达到 200%，电流密度达到 500 mA/cm，电池电压仅为 0.60 V。
