Ru doped MOF-derived carbon materials coupled urea electrolysis promote hydrogen evolution

High-Performance Catalysts : The S-Ni-MOF/NF anode enables ultralow urea oxidation (UOR) overpotentials (180 mV @ 100 mA cm −2 ), while the Ru/S-Ni/NiO-NC/NF cathode achieves exceptional hydrogen evolution (HER) activity (86 mV overpotential). • Dramatic Voltage Reduction via Urea Electrolysis : Integrating these catalysts into an electrolyzer to replace energy-intensive oxygen evolution (OER) with UOR, slashing the cell voltage to only 1.389 V at 10 mA cm −2 in 0.3 M urea electrolyte. • Catalyst Design Strategy : Tailored sulfur-doped MOF anode and ruthenium-engineered cathode offer a promising material approach for driving efficient small-molecule oxidation-assisted hydrogen production. The high energy demand of the oxygen evolution reaction (OER) severely limits the efficiency of water splitting for hydrogen generation. Replacing OER with the thermodynamically more favorable urea oxidation reaction (UOR) offers a promising route to significantly reduce energy consumption. Here, we report highly efficient anode and cathode catalysts enabling a remarkably low-voltage urea-assisted water electrolyzer. A sulfur-doped nickel metal-organic framework on nickel foam (S-Ni-MOF/NF) anode achieves exceptional performance, requiring only 180 mV overpotential for UOR and 470 mV for OER at 100 mA cm −2 . Complementing this, the engineered ruthenium-loaded cathode (Ru/S-Ni/NiO-NC/NF) demonstrates outstanding hydrogen evolution activity with a low overpotential of 86 mV. Crucially, integrating these catalysts into an alkaline water electrolyzer achieves a cell voltage of just 1.52 V at 10 mA cm −2 . Furthermore, substituting the anodic reaction with UOR drastically reduces the cell voltage to 1.389 V at the same current density. This work successfully demonstrates UOR as a highly efficient and practical alternative to OER, significantly advancing energy-saving hydrogen production. It provides a valuable strategy for utilizing small organic molecule oxidation to enable sustainable and economical hydrogen evolution. In-situ S-Ni-MOF/NF and Ru/S-Ni/NiO-NC/NF catalysts grown on the surface of nickel foam for electrooxidation of urea coupled with water electrolysis to produce hydrogen, and achieve sustainable development in hydrogen energy. Download: Download high-res image (210KB) Download: Download full-size image