Fabrication and Characterization of a Novel Composite Magnetic Photocatalyst β-Bi2O3/BiVO4/MnxZn1-xFe2O4 for Rhodamine B Degradation under Visible Light

Constructing a Visible-Active CoFe2O4@Bi2O3/NiO Nanoheterojunction as Magnetically Recoverable Photocatalyst with Boosted Ofloxacin Degradation Efficiency

Constructing visible-light-active Z-scheme heterojunctions has proven fruitful in enhancing the photocatalytic activity of photocatalysts for superior water clean-up. Herein, we report the fabrication of a CoFe2O4@Bi2O3/NiO (CBN) Z-scheme nanoheterojunction. The obtained CBN heterojunction was used for visible-light-assisted degradation of ofloxacin (OFL) in water. The OFL degradation efficiency achieved by the CBN heterojunction was 95.2% in 90 min with a rate constant of kapp = 0.03316 min-1, which was about eight times that of NiO and thirty times that of CoFe2O4. The photocatalytic activity of a Bi2O3/NiO Z-scheme heterojunction was greatly enhanced by the visible activity and redox mediator effect of the cobalt ferrite co-catalyst. Higher charge-carrier separation, more visible-light capture, and the Z-scheme mechanism in the Z-scheme system were the important reasons for the high performance of CBN. The scavenging experiments suggested ●O2- as an active species for superior OFL degradation. The possible OFL degradation pathway was predicted based on LC-MS findings of degradation intermediate products. The magnetic nature of the CBN helped in the recovery of the catalyst after reuse for six cycles. This work provides new insights into designing oxide-based heterojunctions with high visible-light activity, magnetic character, and high redox capabilities for potential practical applications in environmental treatment.

A Z-scheme CdS/BiVO4 photocatalysis towards Eriochrome black T: An experimental design and mechanism study

The synergistic photocatalytic activity was obtained when CdS and BiVO₄ nanoparticles (NPs) were coupled. The samples were characterized by XRD, FTIR, SEM-EDX, and UV-DRS techniques, and their pHpzc was also estimated. The crystallite size of the coupled sample was estimated at 37.3 and 12.5 nm by the Scherrer and Williamson-Hall equations, respectively. The band gaps and the potential positions of VB and CB levels of the semiconductors used were determined. The highest boosted photocatalytic activity was obtained when the CdS: BiVO₄ mole ratio was 1:1. RSM studied the simultaneous interactions between the selected variables, and the model F-value of 110.61> F_{0.05, 14, 13} = 2.4 accompanied by the LOF F-value of 5.20 < F_{0.05, 10, 3} = 8.79 confirm the model significance. The correlation coefficients of R² = 0.9861, the adjusted R² = 0.9710, and the predicted R² = 0.9417, also establish a satisfactory model for processing the experimental data. In the scavenging agent study, photodegradation mechanisms were suggested; among them, the direct Z-scheme mechanism is more favorable for illustrating the EBT-photodegradation by the binary CdS-BiVO₄ photocatalyst. The proposed system, especially the direct Z-scheme mechanism, is suitable as a potential hydrogen production system.

Facile fabrication of hierarchical p-Ag2O/n-Nb2O5 heterojunction microspheres with enhanced visible-light photocatalytic activity

Constructing p–n heterojunction is an efficient strategy to improve the photocatalytic efficiency. Here, we report a hierarchical Ag₂O/Nb₂O₅ heterojunction composite as a novel and efficient visible-light driven photocatalyst. Hierarchical Nb₂O₅ microspheres were prepared by a hydrothermal method, and then the in situ growth of Ag₂O nanoparticles on their surfaces was realized by a simple deposition method. Structural and textural features of the Ag₂O/Nb₂O₅ composites were investigated, revealing that Ag₂O nanoparticles were well distributed on the surface of Nb₂O₅ microspheres. Photocatalytic degradation of rhodamine B (RhB) was significantly enhanced by Ag₂O/Nb₂O₅ photocatalysts under visible light. The optimal Ag/Nb molar ratio was determined to be 0.15 : 1, which yielded a 21.8 times faster degradation rate constant than plain Nb₂O₅ microspheres and had excellent stability for at least 4 catalytic cycles. The superior photocatalytic performance of Ag₂O/Nb₂O₅ photocatalyst can be ascribed to the hierarchical superstructure as well as the heterojunction between Ag₂O and Nb₂O₅, which facilitated the separation of photogenerated charge carriers. This work has potential application in the future for solving environmental pollution.

Constructing p–n heterojunction is an efficient strategy to improve the photocatalytic efficiency.