Modification and characterization of heterojunction srtio3/g-c3n4 for photodegradation of Reactive Red-4 Dyes / Athirah Ainiyah Azman

A heterojunction SrTiO3/g-C3N4 photocatalyst with different mass ratios was prepared by using calcination synthesis. In this process, two conditions were used which are dry and wet methods. RR4 dye was used as a model pollutant to measure the photocatalytic activity of prepared SrTiO3/g-C3N4 at various ratios. Fourier Transform Infrared spectroscopy (FTIR) and Ultraviolet-Visible diffuse reflectance spectra (UV-Vis/DRS) were used for the characterization study. In FTIR, Sr–O and Ti–O bonds were observed at 858 and 596 cm−1 respectively. The -OH peak for SrTiO3 was observed at 1637 cm−1. Ti-OH peak was observed at around 3443–3447 cm−1. The vibration observed at 805 cm-1 indicates the s-triazine ring, and the strong peak observed at 1200-1700 cm-1 indicates the g-C3N4 hetero ring stretching vibration. In UV-Vis/DRS, the absorption edge of pure SrTiO3 was about 380 nm and the absorption edge of g-C3N4 was about 457 nm. The absorption edge of the 10:90 SrTiO3/g-C3N4 presents a bathochromic shift. The bandgap energy for raw g-C3N4, SrTiO3, and 10:90 SrTiO3/g-C3N4 was approximately 2.7, 3.2, and 2.75 eV, estimated using E = hc/λ (hc = 1240). The redshift bandgap energy shifting of the 10:90 SrTiO3/g-C3N4 sample is caused by a substantial chemical interaction between SrTiO3 and g-C3N4, which results in a heterojunction effect for visible light absorption. For photocatalytic degradation, all SrTiO3, g-C3N4 and prepared SrTiO3/g-C3N4 samples have shown photocatalytic degradation under RR4 dye with more than 42% decolourization in 1 h of light irradiation. The modified photocatalyst with mass ratio 10:90 SrTiO3/g-C3N4 under dry method show higher photocatalytic activity as compared to pure SrTiO3 and g-C3N4. Ethanol solvent used in wet method was not suitable media used for SrTiO3 and g-C3N4 in creating the SrTiO3/g-C3N4 heterostructure.