Covalently functionalized graphene by thiourea for enhancing H2-evolution performance of TiO2 photocatalyst

Graphene as a well-known electron cocatalyst can enhance the hydrogen-production performance of photo-catalysts due to its excellent conductivity. For highly efficient graphene-modified TiO2 photocatalyst, besides the speedy electron transfer via graphene, it is significant to raise the interfacial hydrogen-generation reaction rate on the graphene surface. In this paper, thiourea (TU) can covalently functionalize graphene and act as effective H+-adsorbed active sites to improve the hydrogen-production efficiency of graphene-modified TiO2 (TiO2/rGOTU). The TiO2/rGO-TU sample was successfully prepared by a facile nucleophilic substitution reaction between the thiol (-SH) of thiourea and carboxyl (-COOH) of graphene. The TiO2/rGO-TU could possess the maximum H-2-generation rate of 241.83 mu mol h(-1) g(-1), which was 2.33 and 6.60 times greater than that of TiO2/rGO and TiO2, respectively. The enhanced photocatalytic activity of TiO2/rGO-TU can be ascribed to the synergistic effect of graphene and thiourea, namely, the graphene functions as a cocatalyst to capture the photoexcited electrons of TiO2 and the thiourea acts as effectual H+-adsorbed active sites to promote interfacial hydrogen generation. This study presents a feasible strategy for developing grephene-based photocatalysts for prospective applications in the hydrogen-production field.

Automated summary

This study introduces a feasible strategy for developing graphene-based photocatalysts for prospective applications in the hydrogen-production field. By covalently functionalizing graphene with thiourea, the hydrogen-production efficiency of graphene-modified TiO2 photocatalyst was significantly improved. The synergistic effect of graphene and thiourea played a key role in enhancing the interfacial hydrogen-generation reaction rate on the graphene surface.