Amorphous/amorphous Ni-P/Ni(OH)₂heterostructure nanotubes for an efficient alkaline hydrogen evolution reaction

Amorphous/amorphous heterostructures with a large surface area are theoretically anticipated to promote the alkaline hydrogen evolution reaction (HER) activity and stability. However, the growth, characterization and theoretical simulation of amorphous/amorphous nanostructured heterostructures are still challenging due to their atomic isotropy. Herein, a novel and simple strategy is developed to synthesize amorphous/amorphous Ni-P/Ni(OH)₂heterostructure nanotubes by immersing Zn@Ni-P nanowires grown by axial screw dislocation in alkaline solution. When used as an HER catalyst, the Ni-P/Ni(OH)₂nanotubes achieve considerably high electrocatalytic activity and decent stability. The significantly low overpotential of 54.7 mV at a current density of 10 mA cm⁻²is among the best values reported for transition metal phosphides in alkaline solution. Density functional theory calculations indicate that the abundant defect structures of amorphous Ni-P would shift the Ni 3d band center toward the Fermi level, demonstrating an energy barrier decrease for H₂generation. Furthermore, the synergistic effect of amorphous Ni-P and Ni(OH)₂could significantly enhance H₂O dissociation to supply sufficient protons for the HER.