Sustainable microwave-assisted green synthesis of ternary g-C3N4/CdO/In2O3 nanocomposite with enhanced visible-light photocatalytic dye degradation

This study represents a ternary g-C 3 N 4 /CdO/In 2 O 3 nanocomposite synthesis utilising an environmentally friendly microwave-assisted co-precipitation approach. Vitis vinifera (red grape) pulp extract was employed as a fuel for effective microwave absorption, enabling rapid and uniform heating and stabilising agent, promoting uniform nucleation. This provides a sustainable alternative to traditional chemical processes while reducing harmful byproducts and energy usage. The synthesised photocatalyst was fully studied using FTIR, XRD, SEM, XPS, and UV-Vis spectroscopy to establish its structural, morphological, and optical properties. This method results in enhanced visible light photocatalytic efficiency with relative lower band gap (2.66 eV) of g-C 3 N 4 /CdO/In 2 O 3 composite. Surprisingly, the nanocomposite degraded MB dye by over 91.1% in 120 min, outperforming individual components due to improved light absorption, lower bandgap, and efficient charge separation across the heterojunction interface. A thorough scavenger analysis found that hydroxyl radicals and superoxide radicals were the primary factors in dye degradation. The catalyst was recyclable and maintained its activity over five consecutive cycles. This study not only illustrates a green synthesis approach but also provides a highly efficient, reusable, and environmentally friendly photocatalyst for dye-contaminated water cleanup, which is consistent with the goals of sustainable environmental nanotechnology. Overall, this work provides an energy-efficient, eco-friendly blueprint for wastewater remediation, directly contributing to the United Nations’ Sustainable Development Goals, specifically targeting Clean Water and Sanitation (SDG 6) and Responsible Consumption and Production (SDG 12).