Dual Regulation of Graphite-Phase Carbon Nitride by Schottky Junction and D-A₁-A₂ System for Piezo-photothermal Catalysis Self-Fenton Degradation of Tetracycline Hydrochloride

This study introduced an organic polymer (Ph-g-C3N4-Ag) featuring a D-A1-A2 structure created by integrating a benzene ring with a single Ag atom and incorporating reduced graphene oxide (RGO) to form a Ph-g-C3N4-Ag/RGO Schottky junction. This precise construction enhanced the separation efficiency of photogenerated charges while minimizing surface charge complexation. The Ag single-atom optimized photogenerated charge transport through its localized surface plasmon resonance effect, further improving thermal charge transfer at the interface. The RGO as a hole-extraction layer facilitated the effective transfer of photogenerated holes and reduced surface complexation. Additionally, coupling the piezoelectric polarization field with the Schottky junction lessened charge complexation and boosted the charge separation and transport efficiency. The photothermal effect of localized surface plasmon resonance in Ph-g-C3N4-Ag/RGO enhanced carrier migration efficiency and reaction system temperature, which was proved by photothermal experiments and thermal infrared imaging. The catalytic performance of Ph-g-C3N4-Ag/RGO was evaluated by piezo-photothermal catalysis self-Fenton degradation of organic pollutants, and the results showed that the k-value of the tetracycline hydrochloride degradation by Ph-g-C3N4-Ag/RGO-15 was 0.02121 min–1 when 5 mg of Fe2+ was added. Ph-g-C3N4-Ag/RGO-15 showed superior properties compared to those of the other five different g-C3N4 composites. Changes in degradation intermediates were detected and analyzed, thus revealing the synergistic degradation mechanism of the piezoelectric photothermal-catalyzed self-Fenton-catalyzed mineralization system, and it was shown that hydroxyl radical, hole, and superoxide anion radical were the primary active species and played a more important role in the system. This presented a novel approach for the degradation of organic pollutants.