Cobalt-Nanoparticle-Decorated Cobalt–Molybdenum Bimetal Oxides Embedded in Flower-like N-Doped Carbon as a Durable and Efficient Electrocatalyst for Oxygen Evolution Reaction

The development of high-efficiency and cost-efficient oxygen evolution reaction (OER) catalysts is a core issue in the sector of water electrolysis. Cobalt–molybdenum bimetal oxide (Co2Mo3O8), as a kind of non-noble transition-metal oxides, is broadly employed as a good OER catalyst due to its abundant active sites. However, the relatively low conductivity of Co2Mo3O8 limits further improvement in its electrocatalytic performance. Herein, the cobalt nanoparticle-modified Co2Mo3O8 flakes are embedded into the flower-like N-doped carbon (NC) microspheres to effectively improve the electrocatalytic OER performance. The combination of Co2Mo3O8 and NC with a flower-like structure effectively improves the conductivity of the material while enhancing the electrolyte penetration. More importantly, the Co nanoparticles (NPs) on the surface of Co2Mo3O8 flakes have the capability to furnish more active electrocatalytic active sites. The obtained Co NP-modified Co2Mo3O8 embedded flower-like NC microspheres (Co/Co2Mo3O8@NC) exhibited an overpotential of 288 mV at 10 mA·cm–2, which was relatively low in comparison to that of commercial RuO2. Besides, the Co/Co2Mo3O8@NC also shows long-term durability almost without attenuation after the 44 000 s I–T test.