Intimately Contacted Ni2P on CdS Nanorods for Highly Efficient Photocatalytic H2 Evolution: New Phosphidation Route and the Interfacial Separation Mechanism of Charge Carriers

Abstract

A new phosphidation route based on a solvothermal method is demonstrated for the deposition of Ni2P on CdS nanorods photocatalyst with NaBH4 as a crucial reactant and (H2PO2)- as dissolvable P precursor, which leads to a highly crystallized and well contacted Ni2P on CdS in an Ohmic-contact model. On the optimized sample (2%Ni2P/CdS), as high as 1.18 mmol·h-1 H2 evolution rate can be obtained over 50 mg sample, corresponding to an apparent quantum efficiency of 56% (under λ = 435 nm irradiation). The activity is significantly higher than the samples prepared by conventional phosphidation processes and the classical Pt (2%) modified CdS. The remarkable HER performance can be ascribed to the loading of intimately contacted Ni2P, which can promote the separation of photoinduced charge carriers and simultaneously decreases the overpotential for H2 evolution. Furthermore, a reservoir role for photoinduced e- was observed on the deposited Ni2P beyond as a cocatalyst.