Constructing hollow nanoarrays heterostructure of phosphorus doped NiMoO4 and Fe2O3 with interfacial coupling for stable overall water splitting

Abstract

Developing bifunctional electrocatalysts with a strong electron interfacial transfer effect for overall water splitting faces substantial challenges. Herein, we synthesized the Fe₂O₃-regulated P-doped NiMoO₄ hollow nanorod arrays (P-NiMoO₄@Fe₂O₃) on nickel foam. The unique hollow structure leads to abundant exposure of active sites, demonstrating outstanding electrochemical performance. As a bifunctional electrocatalyst in alkaline media, P-NiMoO₄@Fe₂O₃ achieves current densities of 10/300 mA cm⁻² for the hydrogen evolution reaction (HER) with overpotentials of only 45/246 mV, respectively. In the oxygen evolution reaction (OER), it requires overpotentials as low as 210/302 mV to achieve current densities of 10/500 mA cm⁻², respectively. The interfacial coupling promotes both mass transfer and electron transfer, enables to maintain stability for 165 h at 300 mA cm⁻² in the HER and for 100 h at 500 mA cm⁻² in the OER. Furthermore, the P-NiMoO₄@Fe₂O₃||P-NiMoO₄@Fe₂O₃ based electrolyzer cell requires just 1.53 V to reach a current density of 10 mA cm⁻² for overall water splitting, demonstrates stable operation at 100 mA cm⁻² for over 120 h. Density functional theory (DFT) calculations show that P-doping and the construction of heterointerfaces enhance electronic interactions, collaboratively regulate the local electronic environment of atoms, and promote the adsorption and desorption of intermediates, thereby reducing the energy barriers for the catalytic process.