Novel green CQDs/ZnO binary photocatalyst synthesis for efficient visible light irradiation of organic dye degradation for environmental remediation

Abstract

The advancement of effective and sustainable water treatment depends on the creation of a highly active and controllable photocatalyst. A suitable site for increasing the activity of such a photocatalyst is the heterojunction. Organic dyes have become a major source of concern in recent years because they are so common in wastewater. Heavy metals have a high permanence in wastewater and may be carcinogenic. Low-waste, high-performance technologies are needed to remove organic dyes and heavy metals from wastewater. To determine their structural, photochemical, and optical properties, Carbon Quantum Dots (CQDs) (made from Tamarindus indica shell waste), ZnO (from Ficus Benghalensis), and CQDs/ZnO photocatalysts were synthesised using green route techniques, followed by calcination. Malachite Green (MG) and Methylene Blue (MB) are effectively photo-degraded by the synthesised CQDs, ZnO, and Green CQDs/ZnO Binary Photocatalyst under the irradiation of naturally occurring solar light. The maximum photocatalytic activity for MG and MB within 60 min was shown by the Green CQDs/ZnO Binary Photocatalyst, with 100 % and 100 %, respectively. The reduced rate of electron-hole recombination causes effective photocatalytic activity. According to experiments with free radical entrapment, O2 and h+ play an important role in photodegradation. The study thus presents a fresh approach to the synthesis of highly effective binary photocatalysts for their application in environmental remediation.