Engineering the interface of porous CoMoO3 nanosheets with Co3Mo nanoparticles for high-performance electrochemical overall water splitting

Abstract

• Interfacial Co 3 Mo nanoparticles/porous CoMoO 3 nanosheets heterostructures (Co 3 Mo/CoMoO 3 NPSs) grown on nickel foam were successfully fabricated via a simple hydrothermal reaction and subsequent annealing process under controlled atmospheres. • The fabricated Co 3 Mo/CoMoO 3 NPSs exhibit excellent activity and stability for hydrogen evolution reaction (HER) and overall water splitting performance. • The main origins are the interface engineering of Co 3 Mo/CoMoO 3 heterostructure, the unique interfacial electronic structure and increased electrochemical active areas, which remarkably endow Co 3 Mo/CoMoO 3 NPSs with impressive catalytic performance. • Density functional theory calculations illustrate electron transfer from Co 3 Mo to CoMoO 3 at the interfaces, where electron accumulation on CoMoO 3 favors the dissociation of H 2 O molecule, electron-deficient Co atoms in Co 3 Mo have optimized H* absorption energy, Co 3 Mo and CoMoO 3 cooperate synergistically to promoting HER activity in alkaline media. The design of high-performance electrocatalysts for alkaline water splitting is of significant importance for the development of a sustainable hydrogen economy. Herein, heterostructured Co 3 Mo nanoparticles/porous CoMoO 3 nanosheets (Co 3 Mo/CoMoO 3 NPSs) were constructed for alkaline water splitting by annealing CoMoO x nanosheets under controlled atmospheres. Thanks to its interfacial electronic structure and increased electrochemical active area, Co 3 Mo/CoMoO 3 NPSs exhibit impressive hydrogen evolution reaction (HER) activity with an overpotential of 334 mV at 1000 mA cm -2 and a Tafel slope of 46.4 mV per decade in 1.0 M KOH, which outperforms Pt/C catalyst (621 mV and 74.7 mV per decade). Density functional theory calculations illustrate the electron transfer from Co 3 Mo to CoMoO 3 at the interfaces, where electron accumulation on CoMoO 3 favors the dissociation of H 2 O molecule, and electron-deficient Co atoms in Co 3 Mo have optimized H* absorption energy for HER. The Co 3 Mo/CoMoO 3 NPSs also exhibit higher oxygen evolution reaction activity than the RuO 2 catalyst. Moreover, the water electrolyzer using Co 3 Mo/CoMoO 3 NPSs as both cathode and anode only requires 1.59 V to deliver a current density of 100 mA cm -2 in 1.0 M KOH, which outperforms benchmark Pt/C RuO 2 electrodes couple with 1.69 V to reach the same current density, providing great potential for large-scale applications.