Noble-Metal-Free Iron Phosphide Cocatalyst Loaded Graphitic Carbon Nitride as an Efficient and Robust Photocatalyst for Hydrogen Evolution under Visible Light Irradiation

Abstract

Photocatalytic hydrogen (H2) evolution from water is a promising and sustainable approach for solar-to chemical energy conversion. However, the development of an efficient, robust, and low-cost visible-light-driven photocatalyst for H2 evolution is still one of the great challenges. Graphitic carbon nitride (g-C3N4) is an attractive candidate, but the activity of pristine g-C3N4 is largely limited. Herein, for the first time, we report the noble-metal-free iron phosphide cocatalyst decorated graphitic carbon nitride (g-C3N4/FexP) as a photocatalyst for the highly efficient and stable H2 evolution from water splitting irradiated by visible light. The peak H2 evolution rate of g-C3N4/FexP is ca. 277 times higher than that of pristine g-C3N4 and is almost comparable with the g-C3N4 modified by noble metal Pt cocatalyst. Additionally, g-C3N4/FexP demonstrates almost negligible photocatalytic degradation capability after five repeated cycles. Based on the detail analyses of photoluminescence and surface photovoltage spectra, we find the presence of FexP cocatalyst significantly accelerates the separation and transfer of photogenerated electrons of g-C3N4, hence resulting in the high photocatalytic efficiency of g-C3N4/FexP for H2 production. In addition, the adjacent Fe and P atoms in FexP act as dual proton adsorption sites to synergistically facilitate the fast H2 generation from water.