Abstract
The metallic Fe(ii) ion and nonmetallic S codoped g-C3N4 photocatalyst was synthesized through the polymerization of melamine, ferrous chloride and trithiocyanuric acid (TCA) at elevated temperature. The performance of Fe(ii)–S codoped g-C3N4 compounds in RhB photocatalytic degradation was found to increase 5 times. This significant enhancement in catalytic activity is probably related to the enhanced visible light adsorption and the mobility of photoinduced electron/hole pairs, attributable to bandgap narrowing and also lowering in the surface electrostatic potential compared to that of the pure g-C3N4 nanosheets. XRD and XPS results indicate that the Fe species binds with N-atoms to form Fe–N bonds in the state of Fe(ii) ions. Fe(ii) doping increases the specific surface area, and enhances the photoinduced electron/hole pairs illustrated by PL, EIS spectra and transient photocurrent response measurements. The theoretical results show that divalent Fe(ii) ions coordinating in the pore centre among three triazine units form discrete dopant bands and S dopants substituting the N in triazine skeletons excite much stronger delocalized HOMO and LUMO states, facilitating the migration of photogenerated charge carriers, thus enhancing the visible-light driven photocatalytic performance.
Highlights
Pollutant degradation and clean energy generation through semiconductor photocatalysis have been important research topics
The mesoporous structures may be caused by the decomposition of trithiocyanuric acid (TCA) during polymerization process, while the crimped structures are arisen from the larger radii of doped Fe(II) and S than those of the host C and N atoms.[25]
The energy dispersive X-ray (EDX) analysis shows that the composition of the Fe(II)–S codoped g-C3N4 comprising rich carbon (C) and nitrogen (N) with dispersed Fe and S elements
Summary
Pollutant degradation and clean energy generation through semiconductor photocatalysis have been important research topics. One strategy was to fabricate nano/mesoporous structures with a so or hard template,[9,10,11,12] further increasing the speci c surface area, and improving the photon absorption in the visible light region Another was to engineer the band structures of g-C3N4 catalysts to separate the electron/hole pair effectively by coupling with metal particles,[13,14,15] doping metal or non-metal elements,[16,17,18,19,20] and forming heterojunction with other semiconductors, such as ZnO, CuO, TiO2 and CdS,[21,22,23,24] etc. Density functional theory (DFT) calculations demonstrate that the Fe(II) and S doping reduces the bandgap and increases the reactive sites, facilitating the transfer of photogenerated electron–hole pairs
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