High effectiveness self-cleaning activity on TiO2/rGO nanocomposite synthesized by mangosteen (Garcinia mangostana L.) peel extract

• “TiO 2 /rGO was prepared using Garcinia mangostana L. peel extract. • TD-DFT computational method confirmed the effectiveness of photocatalytic process. • TiO 2 /rGO exhibited photocatalytic activity with 99.20% degradation of MB. • TiO 2 /rGO showed a promising self-cleaning material with hydrophilic characteristic. The fabrication of TiO 2 /rGO nanocomposites employing mangosteen peel extract as a bioreductor for self-cleaning applications has been successfully conducted. The research reduced graphene oxide (GO) to rGO using mangosteen peel extract as the reducing agent. TiO 2 synthesis was carried out via a biosynthesis method using mangosteen peel extract while TiO 2 /rGO nanocomposite was obtained using hydrothermal method. TiO 2 /rGO had an anatase phase with a crystal size of 10.439 nm and band gap energy of 3.04 eV which is lower than TiO 2 (3.12 eV). Moreover, TiO 2 /rGO demonstrated mesoporous characteristics with a high surface area of 95.845 m 2 /g. TEM morphology revealed TiO 2 nanoparticle spheres uniformly dispersed on rGO sheets, with 11.2 nm as the average particle size. The time-dependent density functional theory (TD-DFT) computational method showed the distance between methylene blue (MB) atoms and rGO to be 1.6 Å, with the highest oscillator strength of 0.7801, indicating a HOMO −1→LUMO +1 transition, which experiences excitation from π to π*. Photocatalytic self-cleaning tests of the TiO 2 /rGO nanocomposite on MB degradation demonstrated that irradiation with visible light produced superior photocatalytic activity compared to dark and UV light conditions, achieving a degradation percentage of 99.20%. The water contact angle of the TiO 2 /rGO material decreased from 58° before irradiation to 52° after visible light irradiation, indicating the hydrophilic characteristic and effective self-cleaning capabilities of the TiO 2 /rGO nanocomposite.