Lattice-expanded NiSe catalyst via lanthanum incorporation for accelerating urea electrooxidation in assisting water electrolysis

Abstract

Developing bifunctional electrocatalysts for energy-efficient urea oxidation reaction (UOR) and hydrogen evolution reaction (HER) is critical for sustainable hydrogen production and wastewater remediation, yet hindered by sluggish kinetics and insufficient active sites. Herein, we propose demonstrate that lanthanum (La) doping effectively activates nickel selenide (NiSe) by inducing lattice expansion—substituting smaller Ni²⁺ (0.69 Å) with larger La³⁺ ion (1.16 Å)—thereby modulating its electronic structure. The optimized La-NiSe-2 catalyst exhibits markedly enhanced UOR and HER performance: it achieves a UOR current density of 213 mA cm^–2 at 1.6 V vs. RHE (twice that of pristine NiSe) and requires only 135 mV overpotential for HER at –10 mA cm^–2, with a Tafel slope of 78 mV dec^–1. Operando electrochemical impedance spectroscopy and density functional theory calculations reveal that La incorporation enhances charge transfer and strengthens urea adsorption. This work highlights rare-earth-mediated electronic modulation as a viable strategy for designing high-performance bifunctional catalysts for urea-assisted energy and environmental applications.