Graphene-supported C-N-S tridoped TiO_2 photo-catalyst with improved band gap and charge transfer properties

摘要

Photocatalytic performance of TiO_2 nanoparticles was enhanced through (i) band gap shortening using doping of carbon, nitrogen, and sulfur elements as well as (ii) making Schottky barrier using incorporation of graphene (GR) nanosheets, and the photocatalysts of 1.5%Cys/ TiO_2-xwt%GR and 0.5%S/TiO_2-wt%GR with different weight percentages of GR were developed. Cysteine (C_3H_6O_2NS) and thiourea (CH_4N_2S) were used as sources of carbon, nitrogen, and sulfur. The crystalline structure, morphology, chemical composition, and band gap of the prepared photocatalysts were studied using XRD, SEM, EDX, FT-IR, and UV-Vis DRS techniques. It was found that doping of nonmetals and decoration of the doped-TiO_2 nanoparticles over GR was successfully achieved. In addition, UV-Vis DRS findings showed that TiO_2 undergoes considerable reduction in band gap as well as red shift in light's wavelength absorption upon doping of nonmetals and incorporation of GR. The resulting materials were used for degradation of methyl orange (MO) as model organic pollutant under UV and visible light irradiation. According to the findings, and compared to the bare TiO_2, 1.5%Cys/ TiO_2-20wt%GR and 0.5%S/TiO_2-15wt%GR photocatalysts show superior photocatalytic performance under visible light irradiation. The enhanced photocatalytic activity was mainly attributed to the enhanced charge separation and transport by GR substrate. We have also found that content of GR in the hybrid photocatalysts is an important factor affecting the photocatalytic activity with 15-20wt%GR content showing the highest photocatalytic activity.