Interfacial Structure of Water as a New Descriptor of the Hydrogen Evolution Reaction

• Published in: Angewandte Chemie International Edition Vol. 59; no. 50; pp. 22397 - 22402
• Main Authors: Shen, Lin‐fan, Lu, Bang‐an, Li, Yu‐yang, Liu, Jia, Huang‐fu, Zhi‐chao, Peng, Hao, Ye, Jin‐yu, Qu, Xi‐ming, Zhang, Jun‐ming, Li, Guang, Cai, Wen‐bin, Jiang, Yan‐xia, Sun, Shi‐gang
• Format: Journal Article
• Language: English
• Published: Weinheim Wiley Subscription Services, Inc 07.12.2020
• Edition: International ed. in English
• Subjects: Catalysts; Electrodes; hydrogen evolution reaction (HER); Hydrogen evolution reactions; interfacial water structure; Intermediates; Kinetics; Nanoparticles; pH effects; pH-dependence; Platinum; Protons; Raman spectroscopy; Water chemistry
• ISSN: 1433-7851; 1521-3773; 1521-3773
• DOI: 10.1002/anie.202007567

Driven by the persisting poor understanding of the sluggish kinetics of the hydrogen evolution reaction (HER) on Pt in alkaline media, a direct correlation of the interfacial water structure and activity is still yet to be established. Herein, using Pt and Pt–Ni nanoparticles we first demonstrate a strong dependence of the proton donor structure on the HER activity and pH. The structure of the first layer changes from the proton acceptors to the donors with increasing pH. In the base, the reactivity of the interfacial water varied its structure, and the activation energies of water dissociation increased in the sequence: the dangling O−H bonds < the trihedrally coordinated water < the tetrahedrally coordinated water. Moreover, optimizing the adsorption of H and OH intermediates can re‐orientate the interfacial water molecules with their H atoms pointing towards the electrode surface, thereby enhancing the kinetics of HER. Our results clarified the dynamic role of the water structure at the electrode–electrolyte interface during HER and the design of highly efficient HER catalysts. On nickel–platinum alloy nanoparticles under alkaline conditions, the reactivity of interfacial water varies with its structure and the order of water dissociation. The inclusion of nickel re‐orientates interfacial water molecules with their hydrogen atoms pointing towards the electrode surface, thereby enhancing the kinetics of the hydrogen evolution reaction (HER).