Porous and visible-light-driven p–n heterojunction constructed by Bi2O3 nanosheets and WO3 microspheres with enhanced photocatalytic performance

Ultrasensitive photoelectrochemical detection of cancer markers based on heterojunctions constructed from Bi2O3 star-like flower nanoclusters and CdS hollow nanorods

CYFRA21-1 is a tumor marker for lung cancer, and its rapid and accurate detection can provide evidence for the early diagnosis of lung cancer. In this work, Bi-Fe turnbull blue analogues (Bi-Fe-TBA) were synthesized by the self-templating method. Bi2O3-SFNs was prepared by simple oxidation in air using Bi-Fe-TBA as a template. Bi2O3 Star-like Flower Nanoclusters (Bi2O3-SFNs) and CdS Hollow Nanorods (CdS-HNRs) were used to form a unique type II heterojunction for the first time. The arrangement of energy levels between CdS-HNRs and Bi2O3-SFNs, along with their hollow structure and star shape, effectively suppressed the recombination of photogenerated electrons and holes while shortening carrier transport distance. An ultra-sensitive PEC biosensor was developed to detect the lung cancer marker CYFRA21-1, leveraging the superior photoelectric conversion capabilities of Bi2O3-SFNs/CdS-HNRs. The sensor demonstrates outstanding stability, specificity, reproducibility as well as a wide linear range (10-4 - 10 ng mL-1) and low detection limit (4.23 × 10-5 ng mL-1). This study is valuable for the preparation of other functional materials using TBA as a template.

A Simple One-Pot Method for the Synthesis of BiFeO3/Bi25FeO40 Heterojunction for High-Performance Photocatalytic Degradation Applications

This study presents a facile one-pot synthesis method to fabricate BiFeO3-Bi25FeO40-Bi2O3 heterojunction photocatalysts with controllable compositions and pure phases. Three different binary heterojunctions (BiFeO3/Bi25FeO40, BiFeO3/Bi2O3, and Bi25FeO40/Bi2O3) and a ternary BiFeO3/Bi25FeO40/Bi2O3 heterojunction were formed, all exhibiting significantly enhanced photocatalytic performance for the degradation of methylene blue (MB) and phenol under visible light irradiation, outperforming the individual compositions. Notably, the BiFeO3/Bi25FeO40 heterojunction achieved the highest degradation efficiency (93.68% and 83.3% for MB and phenol, respectively) as well as excellent stability. Impressively, the phenol degradation efficiency of BiFeO3/Bi25FeO40 was even over twice that of BiFeO3 and Bi25FeO40, and four times higher than that of Bi2O3. The enhanced photocatalytic activity of the BiFeO3/Bi25FeO40 heterojunction is primarily attributed to the advantageous S-scheme band alignments that facilitate efficient charge separation and enhance redox capabilities. While other heterojunctions also exhibited improved MB and phenol degradation efficiency, each unique combination of materials led to distinct electronic structures and diverse reaction mechanisms. The simplicity and scalability of the synthesis method, combined with the remarkable photocatalytic performance of these BiFeO3-Bi25FeO40-Bi2O3 heterojunction materials, position them as highly promising candidates for applications in environmental remediation and solar energy conversion.

Enhanced visible light driven photoelectrochemical degradation of tetracycline hydrochloride using a BiOI photoanode modified with MnO2 films

Removal of pharmaceuticals in wastewater has been the focus of many research due to the recalcitrant nature and hazardous effects of these compounds. The photoelectrochemical degradation process has proven to be suitable to harness solar energy for the mineralization of organic compounds in wastewater. Herein, we report the application of BiOI/MnO₂ heterostructured anode for the photoelectrochemical degradation of tetracycline hydrochloride in aqueous solution. The photoanode was prepared through electrodeposition technique and fully characterized through microscopic, spectroscopic and electrochemical techniques. The results showed that formation of p-n heterojunction between BiOI and MnO₂ in the photoanode led to improved charge separation which was evident in improved optical and photoelectrochemical properties. The FTO-BiOI/MnO₂ electrode attained a photocurrent density of 0.104 mA cm^-2 with applied potential of 1.0 V (vs Ag/AgCl) which was almost double that of pristine BiOI suggesting efficient charge separation. The heterostructured photoanode achieved 94% removal of tetracycline hydrochloride after 120 min through the PEC degradation process with 61% mineralization efficiency. The electrode showed good reusability and stability with 92% PEC removal after eight cycles. Hence, the FTO-BiOI/MnO₂ has a great potential as anode for PEC wastewater treatments.

Development of Z-scheme bimetallic tungstate-supported nitrogen deficient g-C3N4 heterojunction for the treatment of refractory pharmaceutical pollutants

The binary BMT/ND-GCN-based heterostructure photocatalyst for pharmaceutical industry wastewater treatment.

Fabrication of novel BiVO4/Bi2O3heterostructure with superior visible light induced photocatalytic properties

Heterostructure BiVO₄/Bi₂O₃nanocomposites with enhanced visible light activity are effectively synthesized through an easiest and single step hydrothermal route, using bismuth subnitrate and ammonium meta-vanadate as main raw materials in existence of citric acid. The phase and surface structure, topography and optical properties of synthesized composites are characterized by XRD, SEM, EDX, FTIR, UV-Visible and PL spectroscopy. It was found that 5%BiVO₄/Bi₂O₃(BOBV-5) nanocomposite exhibit excellent photocatalytic performance for rhodamine B dye degradation and tetracyclic under irradiation of visible light as compared to single component i.e. BiVO₄. The increased photocatalytic activity should be ascribed for making p-n heterojunction among p-type Bi₂O₃and n-type BiVO₄. This p-n heterojunction successfully reduce the recombination of photogenerated charge carriers. Furthermore, the BOBV-5 novel photocatalyst shows good stability in constructive five cycles and photocatalytic activity is best for conquering photo corrosion of a photocatalysts. To explain charge migration route, whole photocatalytic mechanism was described in terms of energy band structures. Furthermore, the present work is helpful effort for design of new visible light photocatalytic materials with heterojunction structures.

Photo-induced dissolution of Bi2O3 during photocatalysis reactions: Mechanisms and inhibition method

Photo-induced dissolution greatly limits the application of Bi₂O₃ photocatalyst in water treatment. In this study, mechanisms for the photo-induced dissolution of Bi₂O₃ were proposed. (1) Under UV light, h⁺ forms and diffuses through Bi₂O₃. (2) The h⁺, which reaches the surface of Bi₂O₃ and can be regarded as a monatomic oxygen ion (O_S^-), is weakly bonded to the crystal lattice. (3) Two O_S^- combine and the generated (O-O)^2- ionic group is oxidized by h⁺, resulting in the release of O₂ and dissolution of Bi₂O₃. However, modification of Bi₂O₃ using polyaniline (PANI) greatly inhibits Bi₂O₃ dissolution under UV. Under the PANI to Bi₂O₃ mass ratio of 1.5%, the concentration of produced Bi³⁺ significantly decreased from 2.02 to 0.27 mg/m² with a high methylene blue (MB) degradation efficiency of 98.3%, thanks to the separation of h⁺ from VB-Bi₂O₃ to HOMO-PANI. This study provided the theoretical foundation for the modification and application of Bi₂O₃ in water treatment.