Visible-light-driven iron-based heterogeneous photo-Fenton catalysts for wastewater decontamination: A review of recent advances

Visible-light-driven heterogeneous photo-Fenton process has emerged as the most promising Fenton-derived technology for wastewater decontamination, owing to its prominent superiorities including the potential utilization of clean energy (solar light), and acceleration of equivalent to Fe(II)/equivalent to Fe(III) dynamic cycle. As the core con-stituent, catalysts play a pivotal role in the photocatalytic activation of H2O2 to yield reactive oxidative species (ROS). To date, all types of iron-based heterogeneous photo-Fenton catalysts (Fe-HPFCs) have been extensively reported by the scientific community, and exhibited satisfactory catalytic performance towards pollutants decomposition, sometimes even exceeding the homogeneous counterparts (Fe(II)/H2O2). However, the relevant reviews on Fe-HPFCs, especially from the viewpoint of catalyst-self design are extremely limited. Therefore, this state-of-the-art review focuses on the available Fe-HPFCs in literatures, and gives their classification based on their self-characteristics and modification strategies for the first time. Two classes of representative Fe-HPFCs, conventional inorganic semiconductors of Fe-containing minerals and newly emerging Fe-based metal-organic frameworks (Fe-MOFs) are comprehensively summarized. Moreover, three universal strategies including (i) transition metal (TMs) doping, (ii) construction of heterojunctions with other semiconductors or plasmonic materials, and (iii) combination with supporters were proposed to tackle their inherent defects, viz., inferior light-harvesting capacity, fast recombination of photogenerated carriers, slow mass transfer and low exposure and uneven dispersion of active sites. Lastly, a critical emphasis was also made on the challenges and prospects of Fe-HPFCs in wastewater treatment, providing valuable guidance to researchers for the reasonable construction of high-performance Fe-HPFCs.

Automated summary

Visible-light-driven heterogeneous photo-Fenton process is a promising technology for wastewater decontamination due to its utilization of solar light and accelerated dynamic cycle. Catalysts, as the core constituent, play a pivotal role in activating H2O2. Although various iron-based catalysts have been extensively reported, reviews on Fe-HPFCs, especially from the viewpoint of catalyst-self design, are limited. This state-of-the-art review comprehensively summarizes Fe-HPFCs based on their self-characteristics and modification strategies, and proposes universal strategies to tackle their inherent defects. The challenges and prospects of Fe-HPFCs in wastewater treatment are also discussed, providing valuable guidance for researchers to construct high-performance Fe-HPFCs.