Cerium-Doped Nickel\nPhosphide Nanosheet Arrays as\nHighly Efficient Electrocatalysts for the Hydrogen Evolution Reaction\nin Acidic and Alkaline Conditions

Abstract

Developing inexpensive electrocatalysts with high activity\nand\nstability is of great value for the hydrogen evolution reaction (HER)\nin both acidic and alkaline environments. Despite serving as a model\ncatalyst at the beginning of research studies on transition-metal\nphosphides, nickel phosphide (Ni₂P) has not been an excellent\nHER electrocatalyst to date. Heteroatom incorporation is an effective\nstrategy to optimize the electrocatalytic activities of materials.\nIn this research, Ni₂P nanosheet arrays doped with cerium\nelements were prepared through a facile hydrothermal process and subsequent\nphosphorization. In comparison with other similar phosphor–nickel-based\ncatalysts, the superior electrocatalytic activity for the HER can\nbe achieved in Ce-doped Ni₂P, attributed to the cooperative\neffects from more active sites and higher intrinsic activity derived\nfrom the introduction of Ce heteroatoms. Ce-doped Ni₂P\nwith a Ce/Ni atomic ratio of 12.3% requires as low as 42 and 77 mV\nto achieve 10 mA cm^–2 in acidic and basic environments,\nrespectively. Compared with Pt/C, Ce-doped Ni₂P shows a\nlower overpotential at a high current density (>220 mA cm^–2). The outstanding electrocatalytic stability could be confirmed\nin cycling stability testing of 5000 cycles and continuous testing\nof 100 h at a current density of 20 mA cm^–2. This\nwork offers an efficient and stable alternative to scarce noble metal-based\nelectrocatalysts for sustainable hydrogen generation from water electrolysis.