Preparation and enhanced photocatalytic performance of sulfur doping terminal-methylated g-C3N4 nanosheets with extended visible-light response
Sulfur atom doping has been utilized to optimize the electronic band structure of g-C3N4, however, most doping can reduce the bandgap by no more than 0.2 eV, corresponding to an improved optical absorption only about 36 nm. Herein, sulfur doping terminal-methylated g-C3N4 nanosheet (SMCN) with a tunable bandgap has been prepared for the first time by employing thioacetamide as both sulfur source and blocking agent. Experimental and DFT studies identify that introducing methyl into the melon framework not only acts as a blocking group during the polymerization reaction to generate the structure edge defects, but also reduces the energy barrier of sulfur atom doping. Especially, doping sulfur atom into methylated melon units can split the valence band near Fermi level to generate a new empty midgap electronic state, which leads to a significant decrease of bandgap about 0.7 eV and extends the light-responsive region up to 700 nm. Moreover, due to the changed local charges distribution and lattices strain, a resulting internal electric field is beneficial for the separation of electron-hole pairs. Thus, the as-synthesized SMCN exhibits an outstanding photocatalytic performance in degradation of reactive dye and photocatalytic H2 generation.
- This article is part of the themed collection: 2019 Journal of Materials Chemistry A HOT Papers