Efficient photocatalytic degradation of ofloxacin by a polyimide/phosphate-doped porous coralline carbon nitride S-scheme heterojunction

Abstract

The establishment of a heterojunction between two semiconductors possessing compatible band structures holds significant promise for facilitating the separation and migration of photogenerated carriers, thereby engendering robust photooxidation–reduction capabilities. Herein, a novel S-scheme heterojunction material (PP-CCN), comprising polyimide (PI) and phosphate-doped porous coralline carbon nitride (P-CCN), was meticulously engineered via an in situ wet chemical synthesis approach. The sunlight photocatalytic degradation of ofloxacin in freshwater aquaculture wastewater achieved high efficiency, which was 22.22-fold and 3.61-fold higher than that of pure PI and P-CCN, respectively. The charge transfer mechanism within the S-scheme heterojunction was corroborated through in situ X-ray photoelectron spectroscopy, electron paramagnetic resonance, and theoretical calculations. Furthermore, the PP-CCN/solar photocatalytic system exhibited exceptional versatility across a broad spectrum of concentration gradients, pH conditions, mineralization capacities, and challenging ionic environments or water matrices. Subsequent assessments of reusability and degradation efficacy against 26 kinds of organic pollutants underscored its potential as an efficient treatment modality for multifarious pollution scenarios.