A state-of-the-art review on green synthesis and modifications of ZnO nanoparticles for organic pollutants decomposition and CO₂ conversion

Photocatalysis has emerged as a promising technology to tackle the escalating environmental pollution. Zinc oxide (ZnO), by the virtue of its excellent properties, offers immense potential for simultaneous CO₂ conversion and organic pollutant degradation. The current review comprehensively scrutinizes the green synthesis routes, modifications, and catalytic applications of ZnO nanoparticles for addressing critical environmental challenges. The review explores various green synthesis methods, emphasizing their eco-friendly nature and potential for imparting specific functionalities to the nanoparticles. Subsequently, it explores a wide range of modification strategies, including bimetallic combinations, integration with carbon-based materials, and hybridization with advanced organic polymers, to enhance the catalytic performance of ZnO. The catalytic efficacy of both pristine and modified ZnO nanoparticles in CO₂ conversion is evaluated, along with their in-depth analysis of the underlying mechanisms. Furthermore, the review extensively covers the exploitation of ZnO-based photocatalysts for the decomposition of diverse organic contaminants, like dyes, pharmaceuticals, phenolic compounds, pesticides, herbicides, PAHs, and PFAS. The mechanisms involved in these degradation processes are elucidated, providing insights into the factors influencing photocatalyst efficiency. This review concludes by highlighting the promising prospects of ZnO nanoparticles as sustainable photocatalysts for environmental remediation and the need for further research to optimize their performance and address practical implementation challenges.