Search Results (4)

Addressing the challenges of energy production and environmental sustainability necessitates the development of advanced materials capable of facilitating both photocatalytic reduction and oxidation processes. Here, we report a Z-scheme Ag₃PO₄/CuBi₂O₄ heterojunction photocatalyst, which was fabricated via the in situ anisotropic growth of Ag₃PO₄ nanoparticles on the ends of CuBi₂O₄ microrods. The prepared heterojunction exhibits a low lattice mismatch (~3%) and features a covalently bonded interface, anchored by oxygen atoms, with the formation of P-O-Cu bonds. This interface synergizes with the built-in electric field to drive an efficient Z-scheme charge transfer mechanism, significantly enhancing the separation and migration of carriers. Furthermore, the interfacial chemical bonds induce electron redistribution that effectively weakens the Ag-O bond, thereby activating surface lattice oxygen. As a result, the photocatalyst shows remarkably improved performance for photocatalytic oxygen evolution synchronized with Cr(VI) reduction by enabling both the conventional adsorbate evolution mechanism and the lattice oxygen mechanism. This work provides critical insights into the design of efficient photocatalysts. Full article

In the present work, the photodegradation of Rhodamine B with different pH values by using Bi₂O₃ microrods under visible-light irradiation was studied in terms of the dye degradation efficiency, active species, degradation mechanism, and degradation pathway. X-ray diffractometry, polarized optical microscopy, scanning electron microscopy, fluorescence spectrophotometry, diffuse reflectance spectra, Brunauer–Emmett–Teller, X-ray photoelectron spectroscopy, Fourier-transform infrared spectroscopy, UV–visible spectrophotometry, total organic carbon, and liquid chromatography–mass spectroscopy analysis techniques were used to analyze the crystal structure, morphology, surface structures, band gap values, catalytic performance, and mechanistic pathway. The photoluminescence spectra and diffuse reflectance spectrum (the band gap values of the Bi₂O₃ microrods are 2.79 eV) reveals that the absorption spectrum extended to the visible region, which resulted in a high separation and low recombination rate of electron–hole pairs. The photodegradation results of Bi₂O₃ clearly indicated that Rhodamine B dye had removal efficiencies of about 97.2%, 90.6%, and 50.2% within 120 min at the pH values of 3.0, 5.0, and 7.0, respectively. In addition, the mineralization of RhB was evaluated by measuring the effect of Bi₂O₃ on chemical oxygen demand and total organic carbon at the pH value of 3.0. At the same time, quenching experiments were carried out to understand the core reaction species involved in the photodegradation of Rhodamine B solution at different pH values. The results of X-ray photoelectron spectroscopy, Fourier-transform infrared spectroscopy, and X-ray diffractometer analysis of pre- and post-Bi₂O₃ degradation showed that BiOCl was formed on the surface of Bi₂O₃, and a BiOCl/Bi₂O₃ heterojunction was formed after acid photocatalytic degradation. Furthermore, the catalytic degradation of active substances and the possible mechanism of the photocatalytic degradation of Rhodamine B over Bi₂O₃ at different pH values were analyzed based on the results of X-ray diffractometry, radical capture, Fourier-transform infrared spectroscopy, total organic carbon analysis, and X-ray photoelectron spectroscopy. The degradation intermediates of Rhodamine B with the Bi₂O₃ photocatalyst in visible light were also identified with the assistance of liquid chromatography–mass spectroscopy. Full article

Z-scheme Bi₂MoO₆/Bi₅O₇I heterojunction was constructed by an in situ solvothermal method, which was composed of Bi₂MoO₆ nanosheets growing on the surface of Bi₅O₇I microrods. The antibacterial activities under illumination towards Escherichia coli (E. coli) were investigated. The Bi₂MoO₆/Bi₅O₇I composites exhibited more outstanding antibacterial performance than pure Bi₂MoO₆ and Bi₅O₇I, and the E. coli (10⁸ cfu/mL) was completely inactivated by BM/BI-3 under 90 min irradiation. Additionally, the experiment of adding scavengers revealed that h⁺, •O₂⁻ and •OH played an important role in the E. coli inactivation process. The E. coli cell membrane was damaged by the oxidation of h⁺, •O₂⁻ and •OH, and the intracellular components (K⁺, DNA) subsequently released, which ultimately triggered the apoptosis of the E. coli cell. The enhanced antibacterial performance of Bi₂MoO₆/Bi₅O₇I heterojunction is due to the formation of Z-scheme heterojunction with the effective charge transfer via the well-contacted interface of Bi₂MoO₆ and Bi₅O₇I. This study provides useful guidance on how to construct Bi₅O₇I-based heterojunction for water disinfection with abundant solar energy. Full article

In this paper, a novel S-scheme CuS/Bi₅O₇I heterojunction was successfully constructed using a two-step approach comprising the alkaline hydrothermal method and the adsorption–deposition method, and it consisted of Bi₅O₇I microrods with CuS particles covering the surface. The photocatalytic antibacterial effects on Escherichia coli (E. coli) were systematically examined with visible light exposure. The results suggested that the 3%-CuS/Bi₅O₇I composite showed the optimal antibacterial activity, completely inactivating E. coli (5 × 10⁸ cfu/mL) in 180 min of irradiation. Moreover, the bacterial inactivation process was scientifically described. •O₂⁻ and h⁺ were the major active species for the inactivation of the bacteria. In the early stages, SOD and CAT initiated the protection system to avoid the oxidative destruction of the active species. Unfortunately, the antioxidant protection system was overwhelmed thereafter, which led to the destruction of the cell membrane, as evidenced by the microstructure changes in E. coli cells. Subsequently, the leakage of intracellular components including K⁺, proteins, and DNA resulted in the unavoidable death of E. coli. Due to the construction of the S-scheme heterojunction, the CuS/Bi₅O₇I composite displayed the boosted visible light harvesting, the high-efficiency separation of photogenerated electrons and holes, and a great redox capacity, contributing to an outstanding photocatalytic disinfection performance. This work offers a new opportunity for S-scheme Bi₅O₇I-based heterojunctions with potential application in water disinfection. Full article