POM-assisted coating of MOF-derived Mo-doped Co3O4 nanoparticles on carbon nanotubes for upgrading oxygen evolution reaction

Mo-doped Co3O4 nanoparticles are uniformly coated on the surface of carbon nanotubes for oxygen evolution reaction in the alkaline electrolyte. The doping of high-valence Mo modulates the electronic property and structures of Co3O4, resulting in significant improvement of the electrochemical performance, which outcompetes the benchmark IrO2 and majority of noble-metal-free electrocatalysts. [Display omitted] •A facile protocol has been developed for uniform coating of Mo-doped metal oxides on the surface of carbon nanotubes.•The oxygen evolution reaction performance surpasses those of benchmark IrO2 in the alkaline electrolyte.•The performance improvement results from the electronic and structural modulation of metal oxides owing to Mo doping. Endowing noble-metal-free electrocatalysts with superior oxygen evolution reaction (OER) activity is essential in water electrolysis for massive and cost-effective production of hydrogen fuels. Here, we presented Mo-doped Co3O4 nanoparticles-coated carbon nanotubes (Mo-Co3O4/CNTs), which were fabricated through pyrolysis of CNTs-stringed ZIF-67 with the doping of phosphomolybdic acid. The as-prepared Mo-Co3O4/CNTs exhibits high OER activity and strong durability with the onset potential of 1.42 V and almost constant low overpotential of 280 mV at 10 mA cm−2, which outcompete the benchmark IrO2 electrocatalyst. The outstanding OER performance is mainly attributed that Mo doping modulates the electronic properties and structures of Co3O4, which bring out high proportion of Co2+ active sites, large specific surface area, more electrophilic Co ions and favorable interfacial charge transfer. This work highlights the modification effects of high-valence metal ions on the structures of the electrocatalysts for improving OER performance.