Effect of Contact Mode of TiO2/g-C3N4 Heterojunction on Photocatalytic Performance for Dye Degradation

Two types of TiO2/g-C3N4 heterojunctions, physically and chemically contacted samples, were synthesized to investigate the effect of their contact modes on the photocatalytic activity for dye degradation. The physically contacted TiO2/g-C3N4 heterojunction (TCNPHY) was prepared by an electrostatic assembly process. In addition, the chemically connected heterojunction (TCNCHE) was synthesized by a hydrothermal method accompanied by the formation of Ti-O-C covalent bonds. Fourier-transform infrared and X-ray photoelectron spectroscopies confirmed the formation of Ti-O-C covalent bonds in TCNCHE. Subsequently, their photocatalytic activity for dye degradation was evaluated as a model reaction. The results showed that TCNCHE exhibited higher degradation efficiency than TCNPHY because of its higher UV light absorbance and lower recombination rate than those of the physically contacted sample. These results indicate that the hydrothermal method gives unique advantages in chemically contacted heterojunction construction, which can lead to the improvement of photocatalytic activity. [doi:10.2320/matertrans.MT-M2023092]