Accelerated mass/electron transfer by self-supporting Ni2P@Cu3P heterostructure array to boost alkaline hydrogen evolution at high current density

Abstract

The construction of hydrogen evolution reaction (HER) catalysts at high current density (HCD) is challenging. Electron/mass transfer is hindered by the unsatisfied electrical conductivity at the catalyst-support interface and the massive gas bubbles adhered at the electrolyte-catalyst interface at HCD condition. Herein, a non-precious Ni2P@Cu3P heterostructure constructed by in-situ phase conversion is developed as an electrochemical HER catalyst. The Ni(OH)2 decorated Cu(OH)2 nanowire heterostructure is completely converted into the high electrical conductive Ni2P@Cu3P by a simple phosphatizing method, which not only remain the 3D nanowire array structure but also provide the large specific active surface area and plentiful channels for the fast charge/mass transport to accelerate the HER dynamics. Furthermore, density functional theory calculations reveal that the strong electron interaction between the Ni2P and Cu3P, which can regulate the charge density distribution. As-prepared Ni2P@Cu3P heterostructure displays a more moderate free energy (ΔGH2O = -0.37 eV and ΔGH* = −0.01 eV) for alkaline HER. Benefiting from the complementary advantage of Ni2P and Cu3P, the Ni2P@Cu3P heterostructure exhibits an enhanced HER activity with an overpotential of 279 mV, an excellent long-term stability and durability at 1000 mA·cm−2, providing the great potential for large-scale industrial applications.