Heterostructured ultrafine metal oxides nanoparticles anchored on Co-MOF nanosheets obtained by partial pyrolysis for promoted oxygen evolution reaction

The anchor of functional materials on metal-organic frameworks (MOFs) nanosheets to precisely construct fascinated heterostructures for electrocatalysis is highly promising but challenging owing to the different interfacial thermodynamics and nucleation kinetics. In this work, we design and synthesize ultrafine metal oxides nanoparticles (NPs) homogenously distributed on cobalt-based MOF (Co-MOF) nanosheets for oxygen evolution reaction (OER) by a facile solvothermal reaction and subsequent partially controlled pyrolysis. The ultrafine Co3O4 NPs with a particle size of about 1.5 nm can be obtained from the dispersed elemental Co in Co-MOF and uniformly generated on the surface of the MOF, which is crucial for the formation of the unique heterostructure. The well-designed Co-MOF-350 exhibits an efficient electrocatalytic activity with a low overpotential of 239 mV at a current density of 10 mA cm−2 and a small Tafel slope of 63 mV dec−1, and an outstanding catalytic stability for OER, much superior to the pure Co-MOF and Co3O4 electrocatalyst. The intriguing OER performance mainly originates from the desirable combination of the abundant active sites, the extended electron transport channel between ultrafine metal oxides and Co-MOF nanosheets. More importantly, the work will help to design novel heteroarchitectured MOFs-based composites as efficient and robust electrocatalysts for practical applications.