Designing dual-functional mesoporous g-C3N4 nanosheets doped with KPF6 for H2O2 production and antibiotic degradation

The development of versatile photocatalytic material is an effective strategy to accelerate the generation of clean chemical products and the degradation of antibiotics. Herein, KPF6-modified graphite carbon nitrides were obtained through calcination of melamine-cyanuric acid supramolecular-complex in the existence of potassium hexafluorophosphate (KPF6), and the material with a KPF6 mass fraction of X% was named KPFCN-X. The doping of KPF6 optimized the band gap and visible light absorption capacity of the material, which could effectively accelerate the separation of photo-induced electron-hole pairs, and extended the lifetime of photoexcited electrons. Supported by the mesoporous structure and higher specific surface area, the optimized material provided abundant active sites for effective adsorption and utilization of oxygen molecules thus more conducive to H2O2 production. In the absence of additional O2, the H2O2 yield of KPFCN-1 was essentially the same as in the presence of O2 (2.25mmol·L-1). Additionally, photocatalysis using KPFCN-1 displayed great degradation performance on antibiotics, which removed more than 90% of ciprofloxacin hydrochloride (CIP) and tetracycline hydrochloride (TC) in 180min. Based on the results of various experimental characterizations, the mechanism of photocatalytic H2O2 production and photocatalytic degradation of CIP and TC by KPFCN were proposed. The KPFCN composite holds good promise in photocatalytic production of H2O2 and treatment of antibiotic wastewater.