Built-in electric field induced interfacial charge distributions of Ni₂P/NiSe₂ heterojunction for urea-assisted hydrogen evolution reaction

The direct urea fuel cell (DUFC) with high energy efficiency and convenience is expected to have promising practical applications in green energy development, but it is severely hindered by the slow kinetics of the intrinsic urea oxidation reaction (UOR). Herein, a built-in electric field (BEF) strategy to obtain efficient heterogeneous Ni2P/NiSe2 electrocatalysts as bifunctional electrocatalysts for both the hydrogen evolution reaction (HER) and the UOR is reported. XPS, energy band structure analysis and DFT calculations verify that the BEF in the heterojunction can induce electron transfer between Ni2P and NiSe2. More importantly, the BEF-induced interfacial charge distributions endow the Ni2P/NiSe2 heterogeneous electrocatalysts with optimized binding free energy of the H* and urea intermediates, thereby resulting in an intrinsic enhancement of the catalytic activity. Our work may explore a pathway to design efficient bifunctional electrocatalysts by precisely constructing and manipulating an interfacial BEF.