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, NixP was successfully deposited on g-C3N4 using nickel sulfate (NiSO4) and hypophosphite sodium (NaH2PO2) as Ni and P sources, respectively. The NixP/g-C3N4 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 NixP and g-C3N4, the NixP/g-C3N4 composite demonstrated excellent acid-stable photocatalytic activity for H2 evolution (stable run for 75 h under acidic solution of pH 2). Furthermore, the mechanism for photocatalytic activity of g-C3N4 enhanced by NixP was investigated in detail by steady-state photoluminescence spectra and surface photovoltage spectra, which indicated that separation efficiency of photogenerated carriers from g-C3N4 was effectively enhanced by NixP.