Dopant induced hollow Ni2P nanocrystals regulate dehydrogenation kinetics for highly efficient solar-driven hydrazine assisted H2 production

Abstract

Replacing kinetically sluggish oxygen evolution reaction (OER) with a thermodynamically favorable hydrazine oxidation reaction (HzOR) to produce hydrogen has emerged as a more energy-efficient alternative than water splitting. However, the lack of promising bifunctional electrocatalysts hinders its scalable applications. Here, we report a colloidal synthesis of Mn-dopant induced hollow Ni2P nanocrystals (NCs) using a heat-up approach, which act as superior bifunctional electrocatalysts for both HzOR (55 mV at 10 mA/cm2) and hydrogen evolution reaction (HER, 192 mV at 50 mA/cm2). The two-electrode electrolyzer requires a low cell voltage of 59 mV to achieve 10 mA/cm2 and a current density of ∼ 50.4 mA/cm2 to reach 0.5 V. Theoretical studies unraveled that Mn-doping regulates the electronic structure of Ni2P and optimizes the H* adsorption/desorption and dehydrogenation kinetics. When integrated with a Si photovoltaic device, the bifunctional hollow Mn-doped Ni2P NCs enabled solar-driven hydrazine assisted H2 production with a ∼ 14.6 % efficiency.