Self-assembled FeP/MoP co-doped nanoporous carbon matrix for hydrogen evolution application

Abstract

Metal phosphides are usually being utilized for hydrogen evolution electrocatalysts with enormous potential. Meanwhile, the heterostructure can enhance the catalytic performance for hydrogen evolution reaction (HER). Inspired by the recent preparation of efficient catalysts for HER by using heterogeneous structures of different metal phosphides, we have designed a simple two-step method strategy based on sol-gel/carbonization to prepare the bimetal phosphide coated by nitrogen and phosphorus codoped (N,P-codoped) porous carbon. Phytic acid, chitosan and aniline are adopted to form the N,P-codoped porous carbon framework, the ferric chloride (FeCl3) and ammonium molybdate tetrahydrate (H8MoN2O4) are used as the metal sources to obtained bimetal phosphides (MoP/FeP). The heterostructural interface between the bimetal phosphides of MoP/FeP enhance the catalytic performance, while the N,P-codoped porous carbon promotes the development of reaction kinetics to accelerate the mass and electron transition. The prepared catalysts display limited overpotentials at high current density and exhibit good stability for long-time test. Density functional theory (DFT) is adopted to investigate the interact between the bimetal phosphides, which proves that the heterostructural interface can reduce the reaction Gibbs free-energy (△GH*) and benefit the adsorption / desorption of intermediate H* . This work provides a facile route to the design of the metal phosphides for HER.