Self-derivation and reconstruction of silver nanoparticle reinforced cobalt-nickel bimetallic hydroxides through interface engineering for overall water splitting

Designing efficient and long-lasting non-metal electrocatalysts is an urgent task for addressing the issue of kinetic hysteresis in electrochemical oxidation reactions. The bimetallic hydroxides, catalyzing the oxygen evolution reaction (OER), have significant research potential because hydroxide reconstruction to generate an active phase is a remarkable advantage. Herein, the complete reconstruction of ultrathin CoNi(OH)2 nanosheets was achieved by embedding Ag nanoparticles into the hydroxide to induce a spontaneous redox reaction (SRR), forming heterojunction Ag@CoNi(OH)2 for bifunctional hydrolysis. Theoretical calculations and in situ Raman and ex situ characterizations revealed that the inductive effect of the Ag cation redistributed the charge to promote phase transformation to highly activate Ag-modified hydroxides. The Co-Ni dual sites in Co/NiOOH serve as novel active sites for optimizing the intermediates, thereby weakening the barrier formed by OOH*. Ag@CoNi(OH)2 required a potential of 1.55 V to drive water splitting at a current density of 10 mA cm-2, with nearly 98.6% Faraday efficiency. Through ion induction and triggering of electron regulation in the OER via the synergistic action of the heterogeneous interface and surface reconstruction, this strategic design can overcome the limited capacity of bimetallic hydroxides and bridge the gap between the basic theory and industrialization of water decomposition. (c) 2023 Science Press and Dalian Institute of Chemical Physics, Chinese Academy of Sciences. Published by ELSEVIER B.V. and Science Press. All rights reserved.