Research progress on biochar-based photocatalytic materials for pollutant treatment: Structural regulation, electronic mechanisms, and engineering challenges

Biochar-based photocatalytic materials have shown broad application potential in environmental remediation, including the degradation of organic pollutants in aquatic systems, the reduction of heavy metal ions, and the purification of gaseous contaminants. These advantages stem from their high specific surface area, excellent electrical conductivity, and interfacial regulation capabilities. This review systematically summarizes the structural characteristics of biochar and its multiscale regulation strategies, with particular emphasis on its synergistic roles in the construction of Z-scheme and S-scheme heterojunctions, the regulation of photogenerated carrier dynamics, and the generation and transformation of reactive oxygen species (ROS). The practical performance of biochar-based composites in treating diverse pollutants is critically examined, followed by a comprehensive analysis of current challenges, including raw material variability, material stability, limited mechanistic understanding, insufficient engineering adaptability, and the absence of standardized performance evaluation frameworks. Based on these insights, this paper proposes a forward-looking development strategy centered on green synthesis and data-driven design optimization, offering theoretical guidance and technical pathways to accelerate the large-scale and sustainable application of biochar-based photocatalytic materials in complex environmental systems.