Ultrathin RuRh@(RuRh)O2 core@shell nanosheets as stable oxygen evolution electrocatalysts
The oxygen evolution reaction (OER) is of prime importance in the development of highly efficient electrochemical energy conversion and storage technologies such as water splitting and zinc air battery. Ru-based nanocatalysts are still the best catalytic system for OER, however, one of their greatest challenges for OER is their relatively poor stability. Here, we report a novel architecture of ultrathin RuRh@(RuRh)O2 core/shell nanosheets with core of ultrathin metallic RuRh nanosheets and shell of RuO2/RhO2 oxides as superb electrocatalysts toward OER. The RuRh@(RuRh)O2 core/shell nanosheets can achieve the high electrocatalytic activity toward OER, with a low 245 mV overpotential at 10 mA cm-2 and a Tafel slope of 51.2 mV dec-1, better than most state-of-the-art Ru-based or Ir-based electrocatalysts for OER. Moreover, the RuO2/RhO2 oxides shell protects the normally labile RuRh NS core against dissolution during OER process, revealed by detailed rotating ring disk electrode (RRDE) measurements for simultaneous recording the dissolution of Ru on the ring electrode or the ex-situ measurement of Ru dissolution using the galvanostatic method. Therefore, the RuRh@(RuRh)O2 core/shell nanosheets exhibt much better OER stability in acid media compared with the RuRh nanosheets and commercial RuO2. Theoretical calculations reveal that once the formation of the surface oxidation layers, the O-sites evidentially crossover the Fermi level could guarantee the high electroactivity towards adsorbates while the RuRh core serves as an electron reservoir with high electrical conductivity. The synergistic effect between the core and shell structure leads to the superior OER performance.
- This article is part of the themed collection: Journal of Materials Chemistry A HOT Papers