Degradation of organics using LaFeO3 as a persulfate activator under low-intensity ultra-violet-light irradiation: Catalytic performance and mechanism

Preparation of Novel C/N-Doped LaFeO3 Type Perovskite for Efficient Photocatalytic Degradation of Sodium Humate

LaFeO3 chalcocite precursor was prepared by solid-phase milling method, and LaFeO3-type chalcocite composite catalyst, referred to as LFCN catalyst, was synthesized by in situ doping of carbon and nitrogen (urea, melamine, dicyandiamide, and carbon powder), The catalytic performance of the catalysts was investigated by the different mass ratios of LaFeO3 chalcocite precursor and carbon and nitrogen (1:1, 1:2, and 2:1) and the degradation mechanism. Various characterization analyses, such as X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and Brunauer-Emmett-Teller (BET), showed that the doped composite LFCN catalysts exhibited a hemispherical network structure with a larger specific surface area than that of the pure phase LaFeO3 material. In addition, the LaFeO3 material adjusted the electronic structure of the original LaFeO3 chalcogenide material to a certain extent after in situ doping with organic C and N elements, which enhanced its lattice oxygen oxidation ability. In the study of the catalytic degradation of sodium humate solution under natural light conditions, the catalytic performance was significantly improved compared to that of the pure phase LaFeO3, and 10 mg of the catalyst degraded 30 mg/L of sodium humate solution in 50 min, with a degradation rate increasing from 40 to 98%. The degradation rate increased from 40 to 98% after 4 applications, indicating that the LFCN catalyst has good stability and significant catalytic degradation performance.

Applications of vacancy defect engineering in persulfate activation: Performance and internal mechanism

The vacancy defects in heterogeneous catalysts have received extensive attention for persulfate (PS) activation. Vacancy defects can tune the electronic structure of metal oxides and generate unsaturated coordination sites. Meanwhile, the adsorption energy of reactants on catalyst surface is optimized. Thereby, the reaction energy barrier between catalysts and PS decreases, which could promote catalytic activation and accelerate pollutants degradation. Nowadays, oxygen vacancy (OV), nitrogen vacancy (NV), sulfur vacancy (SV), selenium vacancy (SeV) and titanium vacancy (TiV) have been widely studied with great potential for water remediation. So far, no review was reported regarding the vacancy activated persulfate systems. This paper summarized the types, preparation, mechanism and applications of vacancy in PS systems systematically. In addition, we put forward possible development of vacancy engineering in PS activation systems. It is expected that this review will contribute to the controllable synthesis and applications of vacancies in catalysts for PS activation and contaminants removal.