Fabrication of NiCoP/NiCo2S4 heterostructure for robust electrochemical hydrogen evolution reaction.

Heterostructures comprising NiCoP and NiCo 2 S 4 (referred to as NCP/NCS) were created by incorporating P and S elements into NiCo 2 O 4 (NCO) micro-nanospheres through phosphorization and hydrothermal sulfurization processes. Selective construction of heterogeneous structures can balance the advantages and disadvantages of each single component and is desirable in HER applications. In alkaline media, the resulting product NCP/NCS had an overpotential of 195 mV at a current density of 10 mA cm−2, which is 337 mV higher than that of the original NCO and significantly better than the products of pure phosphide (NCP) and sulfide (NCS). Its Tafel slope was about 83 mV dec−1 and the HER performance did not decay significantly over 48 h. On the other hand, the formation of heterogeneous interfaces improves the intrinsic catalytic activity of the materials. Density functional theory (DFT) simulations show that the hydrogen adsorption capacity at the heterogeneous interface is optimized due to charge enrichment, which in turn enhances the intrinsic activity. • Micro-nanospheres heterostructures was prepared via gas-liquid diffusion method. • Morphology characterization displays the obvious interface and crystalline surface. • The heterostructures delivers a low overpotential than that of single component. • Density functional theory reveals the heterogeneous interface enhance hydrogen adsorption. [ABSTRACT FROM AUTHOR]