Construction of industrial waste red-mud/graphitic carbon nitride S-scheme heterojunction for efficient photocatalytic H2 production

Abstract

Red mud (RM) is a byproduct of bauxite refining, which generated in vast quantities annually, but due to its complex composition and the existence of various hazardous substances, the cost of its recycling and disposal is exorbitant, resulting in both environmental pollution and resource wastage. In this context, based on the idea of turning waste into treasure, we designed a composite material by integrating RM with graphitic carbon nitride (GCN) through a one-step thermal polymerization method for achieving photocatalytic hydrogen (H₂) production. Experimental results indicate that, when the mass ratio of doping in the composite material is 0.8%, the RM/GCN catalyst achieved a hydrogen production rate of 2289 μmol/g under full-spectrum light irradiation, which is significantly higher than the yields obtained from pure GCN or RM alone. In addition, Kelvin probe force microscopy (KPFM) surface potential analysis reveals the S-scheme charge transfer mechanism within the composite material, which not only enhances the light absorption properties, but also effectively suppresses the recombination of photo-generated charge carriers, thus improving the photocatalytic H₂ generation efficiency. This study provides a new design idea for the design of highly efficient photocatalytic hydrogen production materials, and paves the way for the recycling and resource utilization of RM waste.