NiO as a Bifunctional Promoter for RuO2 toward Superior Overall Water Splitting

• Published in: Small (Weinheim an der Bergstrasse, Germany) Vol. 14; no. 16; pp. e1704073 - n/a
• Main Authors: Liu, Jinlong, Zheng, Yao, Jiao, Yan, Wang, Zhenyu, Lu, Zhouguang, Vasileff, Anthony, Qiao, Shi‐Zhang
• Format: Journal Article
• Language: English
• Published: Weinheim Wiley Subscription Services, Inc 19.04.2018
• Subjects: bifunctional promoters; Catalysis; Coupling (molecular); electrocatalysts; Electrolysis; Energy of dissociation; Hydrogen evolution; Nanomaterials; Nanotechnology; nickel oxide; Nickel oxides; ruthenium dioxide; Ruthenium oxide; Water splitting
• ISSN: 1613-6810; 1613-6829
• DOI: 10.1002/smll.201704073

Conventional development of nanomaterials for efficient electrocatalysis is largely based on performance‐oriented trial‐and‐error/iterative approaches, while a rational design approach at the atomic/molecular level is yet to be found. Here, inspired by a fundamental understanding of the mechanism for both oxygen and hydrogen evolution half reactions (OER/HER), a unique strategy is presented to engineer RuO2 for superior alkaline water electrolysis through coupling with NiO as an efficient bifunctional promoter. Benefitting from desired potential‐induced interfacial synergies, NiO‐derived NiOOH improves the oxygen binding energy of RuO2 for enhanced OER, and NiO also promotes water dissociation for enhanced HER on RuO2‐derived Ru. The resulting hybrid material exhibits remarkable bifunctional activities, affording 2.6 times higher OER activity than that of RuO2 and an HER activity comparable to Pt/C. As a result, the simple system requires only 1.5 V to deliver 10 mA cm−2 for overall alkaline water splitting, outperforming the benchmark PtC/NF||IrO2/NF couple with high mass loading. Comprehensive electrochemical investigation reveals the unique and critical role of NiO on the optimized RuO2/NiO interface for synergistically enhanced activities, which may be extended to broader (electro)catalytic systems. Porous nanosheet arrays consisting of strongly interacting RuO2 and NiO nanoparticles are grown vertically on nickel foam through a simple hydrothermal reaction, chemical etching, and thermal treatment process. The self‐supported electrode performs as a highly efficient bifunctional electrocatalyst for overall alkaline water splitting. Its enhanced activity is largely due to the potential‐induced interfacial synergy originating from its rational design.