Re, Ru, and Rh (RRR) catalysts in sustainable hydrogen production via urea-assisted water electrolysis

Green hydrogen generation uses less energy when the anodic urea oxidation process (UOR) is used instead of the oxygen evolution reaction (OER), but there is need for analysis of electrocatalytic urea splitting. In this study, we present the synthesis of Re, Ru, and Rh nanoparticles on carbon nanotubes (RRR NPs@CNT) to achieve remarkable catalytic activity for both UOR and HER (hydrogen evolution reaction) with an alkaline electrolyte. To achieve a current density of 20 mA cm⁻² across a urea electrolyzer, Ru NPs@CNT electrocatalyst required just 1.532 V. By incorporating RRR nanoparticles into CNT, higher oxygen vacancies improved the overall magnetization and involved many spin-polarized electrons through the reaction, accelerating the kinetics of the UOR. Density functional theory (DFT) calculations provided important information on the relationship between the catalyst and OER intermediates by exposing their improved density of states, charge transfer properties, and adsorption capacities. Ru NPs@CNT is a successful electrocatalyst for both UOR/OER and HER, and this type of oxygen vacancy-induced spin-polarized electron offers a reliable benchmark for the investigation of sophisticated electrocatalysts.