Spatial confinement of partially oxidized RuCo alloys in N-doped carbon frameworks for highly efficient oxygen evolution electrocatalysis under acidic conditions

Abstract

The acidic oxygen evolution reaction (OER) is currently one of the main bottlenecks limiting the practical applications of proton exchange membrane (PEM) water electrolysis technology, which is due to the lack of highly reactive, stable and cost-effective electrocatalysts. Herein, the interfacial CoRu-based metal–metal oxide heterostructures embedded in nitrogen-doped carbon nanosheets (RuCoOx-RuCo-NC) were rationally designed and synthesized by using a cobalt-based metal–organic framework (MIL-L-Co) as an effective synthetic platform. RuCoOx-RuCo-NC exhibited superior electrocatalytic OER performance in acidic environments by taking advantage of spatial confinement effect and metal–semiconductor interface. The optimal catalysts afforded a quite small overpotential of only 228 mV to achieve a current density of 10 mA cm−2 and showed excellent long-term durability within 12 h of operation. Specifically, RuCo-RuCoOx@NC enabled a mass activity as high as 0.933 A mgRu-1 at an overpotential of 300 mV, significantly outperforming the benchmark RuO2 catalyst. RuCoOx-RuCo-NC is expected to be one of the best acidic OER electrocatalysts with high apparent and mass activities among Ru/Ir-based catalysts reported.