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 (Co 2 Mo 3 O 8 ), 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 Co 2 Mo 3 O 8 limits further improvement in its electrocatalytic performance. Herein, the cobalt nanoparticle-modified Co 2 Mo 3 O 8 flakes are embedded into the flower-like N-doped carbon (NC) microspheres to effectively improve the electrocatalytic OER performance. The combination of Co 2 Mo 3 O 8 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 Co 2 Mo 3 O 8 flakes have the capability to furnish more active electrocatalytic active sites. The obtained Co NP-modified Co 2 Mo 3 O 8 embedded flower-like NC microspheres (Co/Co 2 Mo 3 O 8 @NC) exhibited an overpotential of 288 mV at 10 mA·cm –2, which was relatively low in comparison to that of commercial RuO 2 . Besides, the Co/Co 2 Mo 3 O 8 @NC also shows long-term durability almost without attenuation after the 44 000 s I – T test.