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

Abstract

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.