Se molarity tuned composition and configuration of Ni₃Se₂/NiSe core-shell nanowire heterostructures for hydrogen evolution reaction

Well-arranged heterogeneous interface is favored to enhance the electrocatalytic activities to utilize the synergistic effects of different crystalline phases. In this work, vertical aligned single crystal Ni₃Se₂ nanowires (NWs) wrapped by ultra-thin NiSe nanoflakes (NFs) with well-arranged heterogeneous interfaces along axial direction were successfully in situ grown on nickel foam (Ni foam) by a simple one-step hydrothermal method without posttreatment. The growth of Ni₃Se₂ NWs follows a surface reaction mechanism by which NiSe reacts with reactive Ni· atoms on surface lattice steps of Ni₃Se₂ nucleuses to grow both along radial and axial directions. The configurations of the products can be tuned from NiSe NFs to the core-shell NWs dominated structures by solely modulating Se molarity in chemical precursors motivated by the accelerated reaction kinetics. The hydrogen evolution reaction (HER) performance was improved with the increase of Se molarity attributing to the increased coverage of high aspect Ni₃Se₂/NiSe core-shell NWs arrays, metallic conductive feature of Ni₃Se₂ skeleton and well-arranged heterogeneous interfaces along the axial direction. The Ni₃Se₂/NiSe core-shell NWs with well-arranged heterogeneous interfaces may also be beneficial to other energy or environmental applications.