Interfacial Ni-O-Ru Coupling in Ultrafast Laser-Shocked NiO/RuO₂ Electrocatalyst for Energy-Saving Urea-Assisted...

In this work, we report the rational design of an interfaced NiO/RuO₂ composite synthesized for the first time using an ultrafast CO₂ laser thermal shock approach. This process transforms Ru-doped Ni(OH)₂ precursors into NiO/RuO₂ composites within 2 min under open-atmosphere conditions, offering a promising route for fabricating metal oxide nanomaterials. Among the series, the NiO/RuO₂-3 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 urea-assisted water splitting, the NiO/RuO₂-3 composite achieves H₂ generation at a low cell voltage of 1.43 V at 10 mA·cm^-2, while showing 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/RuO₂-3 interface. Meanwhile, density functional theory results corroborate that RuO₂ modulates the electronic structure of NiO, optimizes the adsorption energetics of key intermediates, and accelerates both HER and UOR activities. This study proves that a CO₂ laser-induced NiO/RuO₂ composite is an efficient dual-functional electrocatalyst for energy-saving H₂ production with concurrent wastewater remediation.