Potentiostatic Electrodeposition of Binder-Free Ni–W Electrodes for Coupled Energy-Saving Hydrogen Production and Urea Remediation

Abstract

Substituting the kinetically sluggish oxygen evolution reaction with the thermodynamically favorable urea oxidation reaction (UOR) offers a compelling strategy for simultaneously achieving energy-efficient hydrogen production and wastewater remediation. Nevertheless, the design of UOR catalysts that combine high activity with long-term durability remains a significant challenge. Herein, we report the scalable fabrication of binder-free Ni–W nanostructures directly grown on carbon paper through a controlled potentiostatic electrodeposition approach. Electrochemical kinetic analysis confirms that the electrocrystallization follows a diffusion-controlled pathway characterized by instantaneous nucleation and subsequent three-dimensional growth. The optimized Ni–W electrode delivers outstanding UOR activity, reaching a current density of 100 mA cm⁻² at a potential of just 1.77 V versus the reversible hydrogen electrode. In a two-electrode urea electrolyzer configuration, the system achieves 10 mA cm⁻² at only 1.54 V, markedly lower than the voltage required for conventional water splitting. Beyond the energy-efficient hydrogen generation, the system demonstrates meaningful environmental remediation capability, degrading 47% of urea over 30 h of continuous electrolysis. By integrating pollutant removal with electrolytic H₂ production within a single platform, this work establishes a scalable, binder-free catalyst architecture aligned with circular economy principles and advances the frontier of sustainable energy conversion.