Fabrication of 2D/0D ZnO/CuO Z-scheme heterojunctions for enhanced photocatalytic reduction of 2,4-dinitrophenol and 2,4,6-trinitrophenol under visible light

2,4-Dinitrophenol (DNP) and 2,4,6-trinitrophenol (TNP) are highly toxic water pollutants that pose significant environmental and health risks. Developing green and efficient strategies for their removal is imperative. In this study, ZnO nanosheets (NSs) were decorated with CuO nanoparticles (NPs) via an ultrasonic-assisted hydrothermal method, forming ZnO NSs/CuO NPs (ZC-1:1, ZC-1:2) Z-scheme heterojunctions for photocatalytic reduction of DNP and TNP under visible light. Structural and optical characterization confirmed enhanced charge separation and light absorption. The ZC-1:1 heterojunction exhibited superior photocatalytic performance, achieving a complete reduction of DNP in 4 min and TNP in 9 min-4.5 and 2.5 times faster than pristine ZnO and ZC-1:2, respectively. The reaction followed pseudo-first-order kinetics, with rate constants of 1.14 min-1 for DNP and 0.95 min-1 for TNP. ZC-1:1 demonstrated excellent stability, maintaining high efficiency over five cycles. The enhanced activity is attributed to the Z-scheme heterojunction, which facilitates charge carrier separation and electron retention on CuO for effective nitrophenol reduction. This study establishes a promising 2D/0D Zscheme heterojunction for environmental remediation, providing a novel and sustainable approach to converting toxic pollutants into benign products.