Hollow-Co3O4@CoP/NS-RGO Heterojunction Structure Derived fromZIF-67 Promotes Hydrogen Evolution Reaction and OxygenEvolution Reaction Bifunctional Catalysis

In this work, a two-step calcination method tofabricate Co3O4@CoP hollow nanoparticles embedded in N, S-co-doped reduced graphene oxide substrates is reported. Theelectrocatalyst is synthesized through a hydrothermal-calcinationmethod of adding graphene oxide using ZIF-67 as a templatefollowed by an annealing process in the presence of NaH2PO4middotH2O. In the designed electrocatalyst, the formed hollow nano-particles had an average diameter of 100 nm. The synthesizedelectrocatalyst displays a hydrogen evolution reaction overpotentialof 54 mV at 10 mA cm-2current density in 0.5 mol L-1H2SO4solution at room temperature, comparable to Pt/C catalysts. Theoxygen evolution reaction overpotential in 1 mol L-1KOHelectrolyte is 288 mV, which is almost equivalent to that of IrO2.Stated thus, the as-prepared composite catalysts are promising candidates for bifunctional catalysts for water splitting technology,relieving the limitation of commercial catalysts caused by their single catalytic performance.

Automated summary

This work reports the fabrication of Co3O4@CoP hollow nanoparticles embedded in N, S-co-doped reduced graphene oxide substrates using a two-step calcination method. The synthesized electrocatalyst shows comparable hydrogen evolution reaction overpotential to Pt/C catalysts and a high oxygen evolution reaction overpotential similar to that of IrO2. These composite catalysts have great potential as bifunctional catalysts for water splitting technology, overcoming the limitation of commercial catalysts with single catalytic performance.