Black phosphorus supported Ni₂P co-catalyst on graphitic carbon nitride enabling simultaneous boosting charge separation and surface reaction

Rational design and engineering of highly active co-catalysts made of stable and earth-abundant elements is essential to boost the photocatalytic water splitting performances. This paper reports a 2D-black phosphorus (BP) supported Ni₂P (2D-Ni₂P@BP) as a non-precious heterostructure co-catalyst coupled with a 2D porous graphitic carbon nitride nanosheet (CN NSs) photocatalyst to induce visible light photocatalytic hydrogen production. The resulting 2D-Ni₂P@BP/CN composite structure exhibits a remarkable visible light photocatalytic H₂ evolution activity of 858.2 μmol h⁻¹ g⁻¹, revealing ∼50- and ∼5-fold enhancement compared to that of a pristine CN reference and Pt/CN sample, respectively. The dramatic advancement in H₂ evolution could be ascribe to the superior hydrogen evolution reduction (HER) activity of Ni₂P@BP. The excellent HER activity arises from the synergetic effect between BP and Ni₂P in which BP, with its superior electron mobility, is believed to accelerate the charge separation/transfer by mediating the photogenerated electrons from CN NSs to the surface of the catalytically active sites of Ni₂P, while Ni₂P promotes the surface reduction reaction by lowering the H₂-evolution overpotential. It is considered that this work provides a new paradigm for designing advanced, stable, and cost-effective photocatalyst systems for the practical implementation of solar hydrogen production.