Revolutionizing water splitting performance by probing the influence of electron transfer on the NiCr-LDH/VS2/NF heterostructure†

Abstract

Electrocatalytic water splitting for the production of green hydrogen addresses the current energy crisis and potential energy storage. Herein, we have fabricated a low-cost, highly efficient transition metal-based heterostructure of NiCr-LDH over VS₂ using three-dimensional (3D) nickel foam as a substrate. This self-supported NiCr-LDH/VS₂/NF heterostructure catalyst works as an excellent bifunctional electrode to catalyze the oxygen evolution reaction (OER) and the hydrogen evolution reaction (HER) by exhibiting very low overpotential values of 209 mV and 116 mV, respectively, to attain 50 mA cm⁻² current density in 1 M KOH solution. In addition, NiCr-LDH/VS₂/NF shows a cell voltage of 1.545 V to attain 10 mA cm⁻² current density and a 40-hour long-term static stability. The n-type semiconducting NiCr-LDH and p-type conducting VS₂ enhance the electrocatalytic performance by their synergistic effect, changing the surface-modified electronic structure, and generation of improved thin-nanosheet-like mesoporous morphology with superhydrophilic surfaces. Density functional theory (DFT) calculations confirm an interesting charge repopulation observation in both the layers of NiCr-LDH and VS₂ that increases the overall electrocatalytic reaction performance (as confirmed by charge density and Bader charge analysis). This material holds impressive application potential that can guide the design and screening of efficient earth-abundant bifunctional electrocatalysts.