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

Abstract

LaFeO 3 chalcocite precursor was prepared by solid-phase milling method, and LaFeO 3 -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 LaFeO 3 chalcocite precursor and carbon and nitrogen (1:1, 1:2, and 2:1) and the degradation mechanism. Various characterization analyses, such as Xray 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 LaFeO 3 material. In addition, the LaFeO 3 material adjusted the electronic structure of the original LaFeO 3 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 LaFeO 3 , 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.

La/Fe bimetallic MOF-derived p-LaFeO3/n-CdS heterojunction: efficient photocatalytic degradation of organic contaminants and adsorption isotherms

“…C e (mg L −1 ) is the equilibrium dye concentration and K L is the Langmuir equilibrium constant (mg L −1 ), while K F is the Freundlich constant concerning adsorption capacity and n is the linearity index. 51 The results of CR dye fitting for the Freundlich and Langmuir adsorption isotherms are summarized in Table 3, which demonstrates that the Freundlich isotherm model (Fig. S6a, ESI†) has a lower R 2 value than the Langmuir isotherm model (Fig.…”

“…The adsorption study of congo red (CR) dye on the catalyst surface (15 LC) was studied using Freundlich and Langmuir adsorption isotherms. Eqn (4) of the Freundlich isotherm model can be expressed as follows 51 :and eqn (5) is its linearized form:…”

“…A stronger contact between the adsorbate and adsorbent is revealed by higher K F and n (>1) values, which indicate favourable adsorption. 51–53 Based on statistical properties, the adsorption of CR dye is feasible on monolayers and the separation factor ( R L ) assesses its possibility. The separation factor ( R L ) was calculated using eqn (8), and the data are tabulated in Table 4.…”

“…24,25 LaFeO 3 , a semiconducting material of the p-type perovskite metal oxide (ABO 3 ), 26 has gained popularity as a catalytic tool and is used in different fields due to its unique structure and electrical/optical properties. 27 A highly promising candidate with high hydrogen evolution and better photodegradation rates under visible light illumination is a p-type LaFeO 3 material. It has the advantages of narrow band gaps, distinct thermal-chemical stability, quick electronhole pair separation, cost-effectiveness, and non-toxic properties.…”

“…28 However, CdS, an n-type semiconductor has been proven to be visible light active and is frequently used for environmental remediation because of its reasonable bandgap of 2.4 eV. 27,29 Unfortunately, these materials’ intrinsic shortcomings such as their high rate of photogenerated electron–hole pair recombination and lack of solar light absorption restrict their application in photocatalysis. 30 CdS experiences changes such as heterojunction formation and metal/non-metal deposition in order to improve the photocatalytic reaction and lower the rate of electron–hole pair recombination.…”