Amorphous Co3S4 nanoparticle-modified tubular g-C3N4 forms step-scheme heterojunctions for photocatalytic hydrogen production

An effective method to reduce the recombination rate of photogenerated electron-hole pairs was developed by the construction of heterojunctions with rationally designed photocatalysts having a matched band structure. Herein, g-C3N4 hexagonal tubes possessing a lower conduction band were coupled with Co3S4 ultra-fine nanoparticles having relatively higher positions for their conduction band. A step-scheme heterojunction was constructed between these two materials, and through this heterojunction, the spatial charge separation was boosted. The boosted spatial charge separation led to more useful electrons with a higher reduction ability that participated in a photocatalytic H-2 evolution reaction. The Co3S4 ultra-fine nanoparticles act as a mirror to repeatedly scatter and reflect incident light and thus enhance light utilization, and they also accelerate the spatial charge separation. The photocatalytic H-2 evolution activity of the composite catalyst reached 2120 mu mol g(-1) h(-1), which was 176 times higher than that of pristine g-C3N4 tubes. A series of characteristics were determined to investigate the interaction that occurred between the g-C3N4 hexagonal tubes and the Co3S4 ultra-fine nanoparticles, and to study the mechanism of the formed step-scheme. This work will guide the design of step-scheme heterojunction-based photocatalysts to produce H-2 from photocatalytic water splitting.

Automated summary

This study successfully reduced the recombination rate of photogenerated electron-hole pairs by constructing heterojunctions with a matched band structure, leading to improved photocatalytic H-2 evolution. The creation of a step-scheme heterojunction between g-C3N4 hexagonal tubes and Co3S4 ultra-fine nanoparticles enhanced spatial charge separation, resulting in more effective electrons for the photocatalytic reaction.