Highly Stable and Efficient Oxygen Evolution Electrocatalyst Based on Co Oxides Decorated with Ultrafine Ru Nanoclusters.

Abstract

Exploring highly active and durable electrocatalysts for oxygen evolution reaction (OER) is significant to achieve efficient anion exchange membrane (AEM) water electrolysis. Herein, hollow Co-based N-doped porous carbon spheres decorated with ultrafine Ru nanoclusters (HS-RuCo/NC) are reported as efficient OER electrocatalysts via the pyrolysis of carboxylate-terminated polystyrene-templated bimetallic zeolite imidazolate frameworks accommodating Ru (III) ions. The unique hollow structure with hierarchically porous characteristics contributes to the electrolyte penetration for fast mass transport and the exposure of more metal sites. Theoretical and experimental studies reveal the synergistic effect between the in situ formed RuO2 and Co3 O4 as another critical factor for the high OER performance, where the coupling of RuO2 with Co3 O4 can optimize the electronic configuration of RuO2 /Co3 O4 heterostructure and decrease the energy barrier during OER. Meanwhile, the presence of Co3 O4 can efficiently suppress the over-oxidation of RuO2 , endowing the catalysts with high stability. As expected, when the resultant HS-RuCo/NCwas integrated into an AEM water electrolyzer, the obtained electrolyzer exhibits a cell voltage of 2.07 V to launch the current density of 1 A cm-2 and excellent long-term stability at 500 mA cm-2 under room temperature in alkaline solution, outperforming the commercial RuO2 -based AEM water electrolyzer (2.19 V).