Elucidating the Electrochemical Hydrogenation Route by Spatially Isolating Competing Pathways

作者：Ji‐Guang Zhang, Chengyi Zhang, Sibo Wang, Yu Mao, Meng Wang, Qin Yang, Ruoou Yang, Yan Zhang, Shuo Chen, Jinfeng Jia, Ziyun Wang, Yanwei Lum · 发表于：Journal of the American Chemical Society · 年份：2025 · DOI：10.1021/jacs.5c09295 · 被引用次数：6 · 研究领域：CO2 Reduction Techniques and Catalysts、Electrocatalysts for Energy Conversion、Ammonia Synthesis and Nitrogen Reduction

Electrochemical hydrogenation can, in principle, occur through two different possible pathways. One is through the Eley–Rideal mechanism, which involves proton-coupled electron transfer directly from solvent water. Alternatively, hydrogenation can also occur through the Langmuir–Hinshelwood mechanism using surface adsorbed *H. Presumably, the competition between these pathways could exert a considerable influence on product selectivity and reaction rates, however much remains unknown regarding the nature of these processes. Here by employing a Pd membrane reactor to spatially isolate the Langmuir–Hinshelwood pathway, we demonstrate that this has a larger kinetic isotope effect (KIE) as compared to the Eley–Rideal pathway. Hence, we find that hydrogenation through the Eley–Rideal pathway results in a relatively higher incorporation of D when a H 2 O/D 2 O mixture is used as the electrolyte. Finally, we show that increased steric hindrance in the reactant molecule favors the Langmuir–Hinshelwood pathway, which was supported by our theoretical simulations. Our results have important implications on computational modeling of mechanistic pathways and catalyst design for electrochemical hydrogenation reactions.