Upcycling endogenous Fe from coal gasification slag waste into a cocatalyst for the photocatalytic H2 evolution reaction

Abstract

Rather than regarding endogenous Fe in coal gasification slag (CGS) as waste, it could be considered as a potential source to develop an efficient catalyst for energy conversion reactions. Herein, we report an in situ exsolution strategy for upcycling endogenous Fe in CGS waste into a supported Fe₂P cocatalyst via the low-temperature phosphidation for efficient solar H₂ evolution reaction (HER). During phosphidation, ultrasmall Fe₂P nanoparticles (<5 nm) are in situ exsolved and strongly embedded on the surface of the CGS substrate with good dispersion, offering highly stable and active sites for the HER. The as-prepared Fe₂P/CGS cocatalyst exhibits high HER activity and durability in a dye-sensitized system and when combined with semiconductor photocatalysts (CdS and TiO₂). This strategy of upcycling endogenous metals from industrial solid wastes into efficient cocatalysts provides a promising means for developing cost-efficient and high-performance photocatalysts/photocatalytic systems for large-scale solar energy conversion.