Enhancement of the photocatalytic activity of TiO2 modified with carbon dots from tamarind seeds (Tamarindus indica L.) for eco-friendly naphthol green B dye degradation

Titanium dioxide (TiO2) is a widely used photocatalyst, although its performance can be improved by modification with carbon-based nanomaterials. In this study, carbon dots (CDs) derived from tamarind seeds (Tamarindus indica L.) were used to prepare a TiO2/CDs nanocomposite via a hydrothermal method for the photodegradation of naphthol green B (NGB) dye in aqueous solution. The synthesized materials were characterized using XRD, HR-TEM, SEM, FTIR, UV‒Vis, PL, XPS, and BET. The CDs exhibited blue luminescence under UV light, and the average particle size was 7.14 nm. The absorption wavelength of pure TiO2 was 354 nm, the band gap energy was 3.74 eV, and the average particle size was 203.64 nm, whereas the absorption peak of the TiO2/CDs nanocomposite was 347 nm, the band gap energy was 3.61 eV, and the average particle size was 147.67 nm. Photocatalytic degradation of NGB was evaluated under UV irradiation, and the TiO2/CDs nanocomposite showed the highest degradation efficiency, reaching 99.98% after 120 min. These findings indicate that tamarind-seed-derived CDs can serve as a promising biomass-based modifier for TiO2 in NGB photodegradation under the experimental conditions used in this study.