A General Strategy To Fabricate Ni_<i>x</i>P as Highly Efficient Cocatalyst via Photoreduction Deposition for Hydrogen Evolution

Abstract

Presently, precise deposition of transition metal phosphides at the electron outlet of photoactive materials as cocatalysts for hydrogen generation is rarely reported. Demonstrated here is a general photochemical strategy for the preparation of metal phosphides as cocatalysts for hydrogen generation. In this work, Ni x P was successfully deposited on g-C 3 N 4 using nickel sulfate (NiSO 4 ) and hypophosphite sodium (NaH 2 PO 2 ) as Ni and P sources, respectively. The Ni x P/g-C 3 N 4 composite exhibits excellent performance of hydrogen evolution via water splitting (about 8585 μmol g –1 h –1 in a triethanolamine aqueous solution under a 300 W Xe lamp with an AM 1.5G filter). More importantly, due to the intrinsic acid-resistant properties of Ni x P and g-C 3 N 4, the Ni x P/g-C 3 N 4 composite demonstrated excellent acid-stable photocatalytic activity for H 2 evolution (stable run for 75 h under acidic solution of pH 2). Furthermore, the mechanism for photocatalytic activity of g-C 3 N 4 enhanced by Ni x P was investigated in detail by steady-state photoluminescence spectra and surface photovoltage spectra, which indicated that separation efficiency of photogenerated carriers from g-C 3 N 4 was effectively enhanced by Ni x P.