Sulfur- and Carbon-Codoped Carbon Nitride for Photocatalytic Hydrogen Evolution Performance Improvement

In this work, trithiocyanuric acid and graphene oxide quantum dots (GOQDs) served as sulfur (S) and carbon (C) sources to prepared S-, C-codoped carbon nitride (SCCN). The morphology of SCCN changes from lamellar to airbag-like nanostructure with GOQD addition. The photocatalytic hydrogen evolution performance of the optimized SCCN photocatalyst is shown to be 5.6 times higher than that of the CNS photocatalyst. The mechanism of the improved performance is further investigated. It is found that the concentration of hydroxide radical increases during the photocatalytic process, on the basis of the valence band potential of the SCCN photocatalyst moving positively and the surface oxidation energy barrier decreasing. Furthermore, the charge transfer capacity of the SCCN photocatalyst is improved also, so the recombination rate of the photogenerated free charges decreases.