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

Abstract

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.