A study on the role of high-energy holes and reactive oxygen species in photocatalytic degradation using oxygen-doped/biochar-modified 2D carbon nitride

The interplay between high-energy holes and reactive oxygen species (ROS) in the deep mineralization of organic pollutants remains a relatively uncharted domain. Unlocking the mechanisms by which holes facilitate the mineralization of organic contaminants during photocatalysis is critical for achieving deep mineralization. Here, we synthesized an oxygen-doped/biochar-modified 2D C3N4 (termed A-CN) via calcination of a supramolecular precursor assembled on hydroxyl-rich aloe fiber. This dual modification strategy altered the interlayer electronic structure and in-plane electronic configuration of A-CN, promoting its photocatalytic activity. The synchronized evaluation of removal efficiency and toxicity analysis attests to the deep mineralization of the antibiotic contaminant, while the continuous degradation system underscores the photocatalytic stability of A-CN. A-CN exhibited 95 % antibiotic degradation within 1 h, 2.23-fold more efficient than bulk carbon nitride (B-CN), and an 88 % mineralization rate, 4.81-fold higher than B-CN. In a continuous flow device (a flow rate of 2 mL/min), the removal efficiency of antibiotics by A-CN was about 92 %. The degradation mechanism primarily involved hole-mediated deamidation and ROS-driven oxidative ring-opening reactions, facilitating deep mineralization and structural disassembly of antibiotics. This investigation underscores the potential of biochar/oxygen dopinginduced high-energy holes and ROS in photocatalytic pollutant remediation, providing an effective protocol for organic pollutant degradation.