Applying molecular oxygen for organic pollutant degradation: Strategies, mechanisms, and perspectives

Molecular oxygen (O₂) is an environmentally friendly, cost-effective, and non-toxic oxidant. Activation of O₂ generates various highly oxidative reactive oxygen species (ROS), which efficiently degrade pollutants with minimal environmental impact. Despite extensive research on the application of O₂ activation in environmental remediation, a comprehensive review addressing this topic is currently lacking. This review provides an informative overview of recent advancements in O₂ activation, focusing on three primary strategies: photocatalytic activation, chemical activation, and electrochemical activation of O₂. We elucidate the respective mechanisms of these activation methods and discuss their advantages and disadvantages. Additionally, we thoroughly analyze the influence of oxygen supply, reactive temperature, and pH on the O₂ activation process. From electron transfer and energy transfer perspectives, we explore the pathways for ROS generation during O₂ activation. Finally, we address the challenges faced by researchers in this field and discuss future prospects for utilizing O₂ activation in pollution control applications. This detailed analysis enhances our understanding and provides valuable insights for the practical implementation of organic pollutant degradation.