Sub-3 nm Pt3Ni nanoparticles for urea-assisted water splitting

The development of durable efficient electrocatalysts is crucial to alleviate the sluggish kinetics of electrocatalytic urea oxidation reaction (UOR) for energy-saving water splitting. Small Pt-based intermetallic compounds exhibit promising characteristics as UOR catalysts due to their distinctive electronic and geometric structures. This work reported a surfactant-assisted shape evolution method for the controlled synthesis of sub-3 nm Pt3Ni nanoparticles on carbon black to achieve efficient electrocatalytic UOR. The synthesized catalyst features a uniform dodecahedral structure, maximizing Ni utilization and providing multiple active sites for UOR. The Pt3Ni catalyst displays the lower working potential of 1.44 V versus reversible hydrogen electrode, outperforming Pt/C (1.78 V) at 10 mA cm-2, with a smaller Tafel slope of 78.1 mV dec-1, while maintaining exceptional stability during 100 h of continuous urea-assisted water electrolysis. Notably, UOR-boosted system needs only 1.36 V for 10 mA cm-2, significantly lower than the 1.62 V required for traditional water splitting, highlighting its energy-efficient potential for H2 production. Furthermore, theoretical studies indicate that Pt3Ni(111) facilitates the adsorption and activation of urea molecules more effectively than Pt(111), avoiding competition from hydroxyl adsorption. The unique polyhedron structure of the sub-3 nm Pt3Ni catalyst provides the catalytic active dual-sites, further promoting urea interaction. To the best of knowledge, this study represents the first report of Pt-M materials being utilized for the UOR, thereby expanding the application range of Pt-based alloys in urea electrocatalysis.