Dual in-plane/out-of-plane Ni2P-BP/MoS2 Mott-Schottky heterostructure for highly efficient hydrogen production

Abstract

A catalyst innovation with the aim of developing noble-metal-free substitutes is one key aspect for future sustainable hydrogen energy deployment. Herein, we fabricated a dual in-plane/out-of-plane Ni2P-black phosphorus (BP)/MoS2 heterostructure through an all-solution process for the hydrogen evolution reaction (HER). The covalently cross-connected MoS2 and metallic Ni2P-BP interfaces benefit the charge transfer in the electrochemical performances via the Mott-Schottky effect. For the HER, the Ni2P-BP/MoS2 heterostructure shows excellent catalytic activity with a low overpotential of 99 mV at 10 mA cm−2 and a small Tafel slope of 97 mV dec−1 in alkaline electrolyte. The first-principle calculations verify that the work function difference at the Mott-Schottky interface favors electron transfer from Ni2P-BP to outer-surface MoS2 to boost the HER process. Therefore, the Ni2P-BP/MoS2 heterostructure presents near-neutral hydrogen adsorption free energy (ΔGH*, −0.0287 eV), indicating superior HER activity beyond the counterparts (MoS2, BP, and Ni2P-BP). This work inspires possibilities for optimizing BP-based composites through multidimensional interface engineering with the goal of achieving highly efficient hydrogen production electrocatalysis.