Coupling Hydrogen Spillover at Synergistic PtNi/NiInOx Interfaces with Urea Oxidation for Enhancing Water Splitting

Hydrogen spillover is a promising strategy for optimizing electrocatalytic hydrogen production, yet the rational design of spillover-enabled catalysts remains challenging. In this work, bimetallic NiIn layered double hydroxides (LDH) are doped with Pt ions, followed by reconstruction using strong reducing agent, NaBH₄, to prepare PtNi-B3/Ni5In1Ox catalysts. The Pt-Ni alloy exhibits strong H* adsorption capacity, and the NiInOx support serves as an ideal site for H* desorption, forming an interfacial adsorption-transfer-desorption pathway. The density functional theory (DFT) calculations demonstrate that the transfer of adsorbed H* from Pt-Ni alloy to the NiInOx support is promoted by their close work function. The catalyst exhibits exceptional Hydrogen Evolution Reaction (HER) performance, achieving an ultra-low overpotential of 13 mV at 10 mA cm^{- 2} and maintaining stability for over 188 h at 100 mA cm^{- 2}. It demonstrates robust versatility in simulated seawater, industrial conditions, and photovoltaic systems. Furthermore, coupling the urea oxidation reaction (UOR) with HER effectively overcomes the thermodynamic bottleneck of pure water splitting. Accordingly, the required potential is only 1.425 V at 50 mA cm^{- 2}, and its Faradaic efficiency in the initial 60 min is nearly 100%. These demonstrate that the synthesized PtNi-B3/Ni5In1Ox has great potential for industrial applications.