Fabrication of biogenic CDs integrated TiO2 nano-heterojunction for the assessment of visible light mediated photocatalytic dye degradation

Modification of titania nanophotocatalysts is well-recognized for their efficacy in photocatalysis under UV irradiation, particularly in organic dye degradation applications. This research focuses on the structural modification of TiO 2 nanoparticles through the integration of biogenic carbon dots (CDs) to tailor its optical characteristics and thereby to redefine its photocatalytic functionalities. CDs are carbon nanoparticles with dimensions less than 10 nm adorned with organic functional groups which exhibit distinctive optical and electronic properties, rendering them versatile for numerous applications. In this study, carbon dots were synthesized from Mentha piperita (peppermint) using a hydrothermal method. The resulting TiO 2 and CDs@TiO 2 nanomaterials underwent thorough characterization via XRD, FTIR, UV-DRS spectroscopy, SEM, and HRTEM techniques. Crystal violet dye degradation studies were conducted, revealing enhanced degradation efficiency (97 %) for CDs@TiO 2 in comparison to TiO 2 (67 %). The kinetic study revealed that the degradation process fits well with the pseudo second order kinetics. This investigation underscores the pivotal role of carbon dots in augmenting photocatalytic efficiency by mitigating charge carrier recombination, attributed to their electron acceptor-donor characteristics. Additionally, the study portrays the potential of carbon dots derived from eco-friendly sources, such as pepper mint, to serve as a supportive element in the design and advancement of an efficient visible light-based photocatalyst. • CDs synthesized from Mentha piperita via a hydrothermal process. • CDs enhance TiO 2 's optical properties and photocatalytic functions. • CDs@TiO 2 achieved 97% dye degradation vs. 67% for pure TiO 2 . • Biogenic CDs boost TiO 2 's visible light absorption and photocatalytic efficiency.