Optimizing the Band Structure of Crystalline Potassium Poly(heptazine imide) for Enhanced Photocatalytic H2O2Production and Pollutant Degradation

The photocatalytic selective oxygen reduction reaction on a polymeric carbon nitride framework is one of the most promising approaches toward sustainable H2O2 production. Potassium poly(heptazine imide) (K-PHI) was highly active for photocatalytic H2O2 production. Most importantly, by introducing 1-methyl-1H-tetrazole-5-thiol (MTT) into the precursor for the K-PHI synthesis, the size of the layer stacking structure was reduced, the polymerization in the heptazine plane was improved, and the conduction band position was negatively shifted. The MTT-regulated K-PHI (K-PHI-2) showed remarkable H2O2 photoproduction performance, for example, a record high H2O2 photoproduction rate of 41.7 μmol h–1 mg–1 in an acidic environment. Meanwhile, K-PHI-2 showed a significantly enhanced performance in the photocatalytic degradation of the carbamazepine. Additionally, by introducing 5 ppm O3 in the reaction system, ciprofloxacin at a concentration of 100 ppm was eliminated rapidly on K-PHI-2 via a peroxone reaction.