Sub-5 nm Ultra-Fine FeP Nanodots as Efficient Co-Catalysts Modified Porous g-CN for Precious-Metal-Free Photocatalytic Hydrogen Evolution under Visible Light.

Sub-5 nm ultra-fine iron phosphide (FeP) nano-dots-modified porous graphitic carbon nitride (g-CN) heterojunction nanostructures are successfully prepared through the gas-phase phosphorization of FeO/g-CN nanocomposites. The incorporation of zero-dimensional (0D) ultra-small FeP nanodots co-catalysts not only effectively facilitate charge separation but also serve as reaction active sites for hydrogen (H) evolution. Herein, the strongly coupled FeP/g-CN hybrid systems are employed as precious-metal-free photocatalysts for H production under visible-light irradiation. The optimized FeP/g-CN sample displays a maximum H evolution rate of 177.9 μmol h g with the apparent quantum yield of 1.57% at 420 nm. Furthermore, the mechanism of photocatalytic H evolution using 0D/2D FeP/g-CN heterojunction interfaces is systematically corroborated by steady-state photoluminescence (PL), time-resolved PL spectroscopy, and photoelectrochemical results. Additionally, an increased donor density in FeP/g-CN is evidenced from the Mott-Schottky analysis in comparison with that of parent g-CN, signifying the enhancement of electrical conductivity and charge transport owing to the emerging role of FeP. The density functional theory calculations reveal that the FeP/g-CN hybrids could act as a promising catalyst for the H evolution reaction. Overall, this work not only paves a new path in the engineering of monodispersed FeP-decorated g-CN 0D/2D robust nanoarchitectures but also elucidates potential insights for the utilization of noble-metal-free FeP nanodots as remarkable co-catalysts for superior photocatalytic H evolution.