The need to protect the environment, conserve energy and reduce carbon dioxide emission is currently a global objective among researchers and policymakers. Currently, photocatalytic technology is considered a promising solution in environmental protection and energy conservation owing to its environmental benefits and low cost. Of all the various photocatalytic available, titanium oxide (TiO2) is widely preferred due to its stability, low cost and high efficiency. Unfortunately, it is associated with a quick recombination of the photoinduced electrons and a wide band gap that limits its efficiency. Therefore, significant efforts have been directed towards offering solutions to this problem.
Among the proposed methods, narrow band gap heterojunction is capable of not only suppressing the recombination of the charge carriers but also allowing the photocatalytic capability in the presence of visible light. Consequently, a hybrid of g-C3N4 with TiO2 exhibit enhanced photocatalytic performance in the presence of visible light. This is due to the unique physical and chemical properties of g-C3N4. However, g-C3N4/TiO2 hybrid composite has disadvantages resulting from insufficient absorption of light and separation of photogenerated charge carriers that limit its effectiveness. Also, the large energy surface leads to the aggregation of TiO2 nanoparticles on the g-C3N4 substrate.
In a recently published literature, sulfur doping has been utilized to improve the photocatalytic activities of g-C3N4. This has significantly attracted interests amongst researchers as it possesses the desirable electronic structure and efficiency in the photo-induced electron transportation. However, little has been reported about coupling S-C3N4 and TiO2.
Shandong University researchers led by Professor Shiping Xu used a facile impregnation technique to fabricate a nanocomposite of TiO2 nanoparticles coupled with a sulfur-doped C3N4 layer (SCNT). For the synthesis, the group of authors utilized tri-t hiocyanuric acid as a precursor for sulfur. Their work is currently published in the journal, Applied Surface Science.
The authors observed that the fabricated nanocomposite exhibited significantly improved photocatalytic activities in the removal of pollutants as compared to pure TiO2 and g-C3N4 /TiO2. For instance, a rate constant of 8.6 and 2.6 times more than that obtained in pure titanium oxide and g-C3N4 /TiO2 composite respectively was achieved during the degradation of MO. Additionally, the synthesized SCNT exhibited strong capability for absorption of visible light.
The study by Shandong University scientists is the first to successfully synthesize sulfur-doped coupling of g-C3N4 and pure TiO2. The improvement in the photocatalytic efficiency of the resultant nanocomposite was attributed to its capability of inhibiting the aggregation of TiO2 nanoparticles on the g-C3N4 substrate as well as suppressing the recombination of photoinduced electron pairs. Consequently, the introduced sulfur regulated g-C3N4 morphology thus resulting in the formation of ultrathin g-C3N4 layer and bar-like g-C3N4 /TiO2 nanocomposite which enhanced its entire efficiency like visible light absorption capacity. Therefore, their work is a promising solution for the synthesis and use of highly efficient photocatalyst in the presence of visible light irradiation for environmental purification and pollutants removal.
Zhao, Y., Xu, S., Sun, X., Xu, X., & Gao, B. (2018). Unique bar-like sulfur-doped C3N4/TiO2 nanocomposite: Excellent visible light driven photocatalytic activity and mechanism study. Applied Surface Science, 436, 873-881.Go To Applied Surface Science