Abstract

In this work, we report the rational design of an interfaced NiO/RuO 2 composite synthesized for the first time using an ultrafast CO 2 laser thermal shock approach. This process transforms Ru-doped Ni(OH) 2 precursors into NiO/RuO 2 composites within 2 min under openatmosphere conditions, offering a promising route for fabricating metal oxide nanomaterials.

Among the series, the NiO/RuO 2 -3 composite, prepared with an equimolar ratio of Ni and Ru precursors, exhibits exceptional dual-functional electrocatalytic activity, requiring only 35 mV overpotential for the hydrogen evolution reaction (HER) and 1.38 V vs. the reversible hydrogen electrode for the urea oxidation reaction (UOR) at 10 mA⸱cm −2 . When integrated into ureaassisted water splitting, the NiO/RuO 2 -3 composite achieves H 2 generation at a low cell voltage of 1.43 V at 10 mA⸱cm −2 , while remarkable stability over 100 h. In situ Raman spectroscopy reveals negligible surface reconstruction during the HER but distinct NiOOH formation during the UOR at the NiO/RuO 2 -3 interface. Meanwhile, density functional theory results corroborate that RuO 2 modulates the electronic structure of NiO, optimizes the adsorption energetics of key intermediates, and accelerates both HER and UOR activities. This study proves that CO 2 laserinduced NiO/RuO 2 composite is an efficient dual-functional electrocatalyst for energy-saving H 2 production with concurrent wastewater remediation.