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

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 (ΔG_H*, −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.