Optimizing OH* adsorption via Zn doping into Ni2P/CoP heterostructures enables high catalytic activity toward alkaline hydrogen evolution reaction

Abstract

Activity problems caused by OH* adsorption in alkaline hydrogen evolution reaction (HER) are one of the key issues that hinder the improvement of the water electrolysis efficiency. Herein, we report an oxophilic Zn doping strategy to design a Zn-incorporated Ni2P/CoP heterostructure catalyst on nickel foam (Zn-Ni2P/CoP) via a facile hydrothermal-calcination phosphorization method. The optimal Zn-Ni2P/CoP features a dense nanoneedle architecture integrated with a Ni2P/CoP heterostructures, which synergistically modulates the electronic structure of Ni and Co, enhances active site exposure, and facilitates mass transport. More importantly, Zn doping facilitates the formation of four-coordinate hydrogen-bonded water (4-HB·H2O), strengthens the interaction between interfacial water molecules and Zn-Ni2P/CoP. Additionally, the adsorption energy of OH* is optimized, thereby accelerating the water dissociation process. Benefiting from these synergistic effects, Zn-Ni2P/CoP exhibits exceptional alkaline HER performance, achieving current densities of 100, 200, and 500 mA cm-2 at overpotentials of 133, 156, and 226 mV, respectively. Moreover, it delivers a Tafel slope of 71.7 mV dec-1 and maintains excellent stability, operating continuously for 190 h at 10 mA cm-2 and 100 h at 100 mA cm-2. This work provides a design approach to modulate OH* adsorption behavior and promote water dissociation for the development of high-performance alkaline HER catalysts.