Enhanced photocatalytic performance of morphologically tuned Bi 2 S 3 NPs in the degradation of organic pollutants under visible light irradiation

A photoelectrochemical cytosensor based on a Bi2S3-MoS2 heterojunction-modified reduced oxide graphene honeycomb film for sensitive detection of circulating tumor cells

A novel photoelectrochemical (PEC) cytosensor for the ultrasensitive detection of circulating tumor cells (CTCs) was developed. The bio-inspired reduced graphene oxide (rGO) honeycomb film photoelectrode was fabricated via a "breath figure" method, followed by the self-assembly of a Bi2S3-MoS2 heterojunction. The resulting Bi2S3-MoS2 heterojunction-modified rGO honeycomb film was employed as a sensing matrix for the first time. Compared to the smooth rGO film, the significant enhanced photocurrent of the photoelectrode under visible light was attributed to its improved visible light absorption, increased surface area and enhanced separation efficiency of photo-generated electron-hole pairs, which met the requirements of the PEC sensor for detecting larger targets. By virtue of the photocurrent decrease due to the steric hindrance of MCF-7 cells, which were captured by an aptamer immobilized on the surface of the photoelectrode, a cytosensor for detecting CTCs was achieved, showing a wide linear range of 10-1 × 105 cells per mL and a low detection limit of 2 cells per mL. Furthermore, MCF-7 cells in human serum were determined by this PEC biosensor, exhibiting great potential in the clinical detection of CTCs.

Advancements in TiO2-based photocatalysis for environmental remediation: Strategies for enhancing visible-light-driven activity

Researchers have focused on efficient techniques for degrading hazardous organic pollutants due to their negative impacts on ecological systems, necessitating immediate remediation. Specifically, TiO2-based photocatalysts, a wide-bandgap semiconductor material, have been extensively studied for their application in environmental remediation. However, the extensive band gap energy and speedy reattachment of electron (e-) and hole (h+) pairs in bare TiO2 are considered major disadvantages for photocatalysis. This review extensively focuses on the combination of semiconducting photocatalysts for commercial outcomes to develop efficient heterojunctions with high photocatalytic activity by minimizing the e-/h+ recombination rate. The improved activity of these heterojunctions is due to their greater surface area, rich active sites, narrow band gap, and high light-harvesting tendency. In this context, strategies for increasing visible light activity, including doping with metals and non-metals, surface modifications, morphology control, composite formation, heterojunction formation, bandgap engineering, surface plasmon resonance, and optimizing reaction conditions are discussed. Furthermore, this review critically assesses the latest developments in TiO2 photocatalysts for the efficient decomposition of various organic contaminants from wastewater, such as pharmaceutical waste, dyes, pesticides, aromatic hydrocarbons, and halo compounds. This review implies that doping is an effective, economical, and simple process for TiO2 nanostructures and that a heterogeneous photocatalytic mechanism is an eco-friendly substitute for the removal of various pollutants. This review provides valuable insights for researchers involved in the development of efficient photocatalysts for environmental remediation.

A cathodic photoelectrochemical biosensor based on CRISPR/Cas12a trans-cleavage mediated p-n heterojunction quenching mode for microRNA determination

In this study, a cathodic photoelectrochemical (PEC) bioanalysis for sensitive determination of microRNA (miRNA) has been constructed based on CRISPR/Cas12a trans-cleavage mediated [(C6)₂Ir(dcbpy)]⁺PF₆^- (C6 represents coumarin-6 and dcbpy represents 4,4'-dicarboxyl-2,2'-bipyridine)-sensitized NiO photocathode and p-n heterojunction quenching mode. The [(C6)₂Ir(dcbpy)]⁺PF₆^--sensitized NiO photocathode exhibits a stable and dramatically improved photocurrent signal due to highly effective photosensitization of [(C6)₂Ir(dcbpy)]⁺ PF₆^-. Then Bi₂S₃ quantum dots (Bi₂S₃ QDs) is captured on the photocathode, resulting in markedly quenching of the photocurrent. When target miRNA is specifically recognized by the hairpin DNA to stimulate the trans-cleavage activity of CRISPR/Cas12a, leading to the leave of the Bi₂S₃ QDs. The photocurrent is gradually recovered with the increasing target concentration. Thus, the quantitative signal response to target is achieved. Benefiting from excellent performance of NiO photocathode, intense quenching effect of p-n heterojunction and accurate recognition ability of CRISPR/Cas12a, the cathodic PEC biosensor shows a wider linear range over 0.1 fM-10 nM, with a low detection limit of 36 aM. Also, the biosensor exhibits satisfying stability and selectivity.

The Solid-State Synthesis of BiOIO3 Nanoplates with Boosted Photocatalytic Degradation Ability for Organic Contaminants

BiOIO₃ exhibits excellent oxidation capacity in the photocatalytic degradation of contaminants thanks to its unique polarized electric and internal electrostatic field. However, the synthetic method of BiOIO₃ nanomaterials is mainly focused on hydrothermal technology, owing to its high energy consumption and time-consuming nature. In this work, a BiOIO₃ nanosheet was prepared by a simple solid-state chemical reaction, which was identified by XRD, EDS, XPS, and HRTEM. Benefiting from the strong oxidation ability of the valence band maximum, the distinctive layer structure, and the promoted generation of ·O₂^-, the BiOIO₃ nanosheet exhibits excellent photo-degradation activity for methyl orange (MO) and its apparent rate constant is 0.2179 min^-1, which is about 3.02, 8.60, and 10.26 times higher than that of P25, BiOCl, and Bi₂O₂CO₃, respectively. Interestingly, the BiOIO₃ nanosheet also has good photocatalytic degradation performance for phenolic compounds; in particular, the degradation rate of BPA can reach 96.5% after 16 min, mainly due to hydroxylation reaction.

Integration of Bismuth sulfide/functionalized halloysite nanotube composite: An electrochemical tool for diethofencarb analysis

Diethofencarb (DFC) is a fungicide used in agricultural fields and it's overe use makes a negative impact in the real-time environment. Here in this work, a semi-conductive urchin like Bismuth sulfide (Bi₂S₃) anchored with tubular structure functionalized halloysite nanotube (F-HNT) was hydrothermally synthesized and used for the electrochemical detection of DFC. Various analytical and microscopic techniques were used to analyze the structure, crystalline nature, and purity of the as-prepared F-HNT@Bi₂S₃. Moreover, the cyclic voltammetry technique was used to analyze the electrochemical studies of the F-HNT@Bi₂S₃ modified glassy carbon electrode (GCE). A high synergetic relationship between the Bi₂S₃ and F-HNT provides a large surface area and better detection of DFC. The amperometry i-t technique result shows that the prepared composite exhibits a wide linear range of 0.0053-526.62 μg L^-1, a low detection limit of 0.0032 μg L^-1, and very good stability over 2000 s. Notably, our proposed sensor can determine the DFC spiked tomato and water samples with a high recovery range and proven the viability for real-time analysis. Finally, all the above-mentioned study results prove that the F-HNT@Bi₂S₃ could be used as an electrochemical probe for the detection of DFC.

Low temperature energy- efficient synthesis methods for bismuth-based nanostructured photocatalysts for environmental remediation application: A review

Bismuth-based composite materials have unique structural, chemical, optical, and electrical properties that are highly beneficial in Photocatalysis. The layered structure and tunable bandgap properties of the Bismuth-based composites are advantageous for the absorption of solar light efficiently. Also, these properties help the separation and recombination of photogenerated charge carriers, leading to enhancement in the photocatalytic activity. Synthesis of the catalyst at a lower temperature to produce catalyst reduces the production cost and electrical energy consumption. This review provides an overview of the recent development in Bismuth-based composite nanostructured photocatalytic materials, mainly using low-temperature driven synthesis methods. Herein, we have mainly summarized the primarily used low temperature-based synthetic routes, particularly in the temperature range of 50-300 °C for synthesizing Bismuth-based composite materials. In addition to this, the photocatalytic mechanism, the textural, structural, electronic, and photocatalytic properties of the synthesized photocatalysts are discussed. The literature shows that the surface area of the composite Bismuth-based photocatalytic materials synthesized using the low-temperature synthetic route is in the range of 1.5-81 m²/g and can be activated by solar, ultraviolet, and Light Emitting Diode (LEDs) light irradiation based on the synthetic route. Their photocatalytic performance and structural stability are excellent and utilized for several runs. The comprehensive understanding of the low-temperature synthesis of Bismuth-based composite materials for visible light-activated photocatalytic applications provided will be useful for developing photocatalytic materials on an industrial scale due to energy-efficient synthetic routes. Furthermore, the prospects of low temperature-driven Bismuth-based composite synthesis routes are discussed.

Citric acid-capped NiWO4/Bi2S3 and rGO-doped NiWO4/Bi2S3 nanoarchitectures for photocatalytic decontamination of emerging pollutants from the aqueous environment

Herein, we describe the successful synthesis of NiWO₄/Bi₂S₃ and reduced graphene oxide (rGO-NiWO₄/Bi₂S₃) nanocomposites through a simple green sol-gel approach. The fabricated composites were subsequently characterized by Fourier transform infrared (FT-IR), X-ray diffraction (XRD), scanning electron microscopy (SEM), Energy Dispersive X-Ray Analysis (EDX) and ultraviolet-visible spectroscopy (UV-VIS) spectroscopic analyses. Dielectric properties were done by a precision impedance analyzer. Tanδ and dielectric constant for NiWO₄/Bi₂S₃ and rGO-NiWO₄/Bi₂S₃ were 1.811, 292818, and 0.2970, 344574, respectively, at 20 Hz. The photocatalytic performance of NiWO₄/Bi₂S₃ and rGO-NiWO₄/Bi₂S₃ was investigated against methylene blue and methyl orange dyes in an aqueous medium. NiWO₄-Bi₂S₃ showed degradation of methylene blue 15.52% after 20 min, 21.8% after 30 min and 46.8% after 40 min. Similarly, for methyl orange dye it was 18.1% after 20 min, 54% after 30 min and 59.36% after 40 min. Compared to NiWO₄/Bi₂S_3, rGO-NiWO₄/Bi₂S₃ exhibited superior degradation efficiency of 7.5% (20 min), 25.24% (30 min) and 57.71% (40 min) for methylene blue, and 35.7% (20 min), 56.98% (30 min) and 72.42% (40 min) for methyl orange under sunlight. This enhancement in photocatalytic and dielectric properties might be attributed to the presence of graphene in rGO-NiWO₄/Bi₂S₃ nanococomposite. Different factors such as effect of time, pH, dose of catalyst, concentration of dye were optimized and the reusability of superior catalyst rGO-NiWO₄/Bi₂S₃ was also checked for four cycles. In conclusion, promising photocatalytic and dielectric properties of rGO-NiWO₄/Bi₂S₃ suggest its potential applications in the photocatalytic degradation of organic pollutants and energy storage materials. This study provides a well-developed route to exploit metal sulphide/oxide nanocomposites in environmental remediation and energy storage devices.

Surface-constructing of visible-light Bi2WO6/CeO2 nanophotocatalyst grafted PVDF membrane for degradation of tetracycline and humic acid

The synthesis of Bi₂WO₆ and CeO₂ photocatalytic nanomaterials exhibit a great ability to photodegrade the antibiotics and shown excellent oxidation of various organic pollutants. Heterostructure 1:1 & 2:1 Bi₂WO₆/CeO₂ nanocomposite was successfully synthesized via the facile sono-dispersion method and exquisite photocatalytic activity. The 0.5 wt% of nanocomposites were well-grafted on PVDF membrane surface via an in-situ polymerization method using polyacrylic acid. The fourier transform infrared (FTIR) spectra demonstrated that the network formation in PVDF induced by the -COOH functional group in acrylic acid. The grafted membrane morphology and strong binding ability over the membranes were validated by scanning electron microscope with energy dispersion (SEM-EDS) and X-ray photoelectron spectroscopy (XPS), respectively. The permeate flux of 49.2 L.m^-2 h^-1 and 41.65 L.m^-2 h were observed for tetracycline and the humic acid solution respectively for 1 wt% of PVP and 0.5 wt% of photocatalytic nanomaterials in PVDF membrane. The tetracycline and humic acid photodegradation rate of 82% and 78% and total resistance of 1.43 × 10¹⁰ m^-1 and 1.64 × 10¹⁰ m^-1, 83.5% and 77% flux recovery ratio were observed with N5 membrane. The 2:1 Bi₂WO₆/CeO₂ nanocomposite grafted membrane showed a high permeate flux and better photodegradation ability of organic pollutants in the wastewater.

Recent insights into SnO2-based engineered nanoparticles for sustainable H2 generation and remediation of pesticides

Due to the ongoing industrial revolution and global health pandemics, solar-driven water splitting and pesticide degradation are highly sought to cope with catastrophes such as depleting fossil reservoirs, global warming, and environmental degradation.

Investigation of EG-Bi2S3 nanorods photocatalytic activity under visible light for dye degradation from aquatic system

Bi₂S₃, 5 ml EG-Bi₂S₃, and 10 ml EG-Bi₂S₃ were synthesized by employing solvothermal route. X-ray diffraction, UV-vis absorption, photoluminescence, Raman, scanning electron microscopic studies confirmed the structural, optical, morphological behaviors. The XRD pattern of Bi₂S₃, 5 ml EG-Bi₂S₃, and 10 ml EG-Bi₂S₃ was correlated well with JCPDS # 65-2435. The crystallite size was found to be 57, 49, and 40 nm. The photoluminescence spectra showed semiconducting property of prepared Bi₂S₃, 5 ml EG-Bi₂S₃, and 10 ml EG-Bi₂S₃. The absorption spectra of Bi₂S₃, 5 ml EG-Bi₂S₃, and 10 ml EG-Bi₂S₃ nanorods were well matched with the spectra of a previous report. The bandgap values of Bi₂S₃, 5 ml EG-Bi₂S₃, and 10 ml EG-Bi₂S₃ were calculated to be 1.56, 1.45, and 1.3 eV in reducing order. The morphology of Bi₂S₃, 5 ml EG-Bi₂S₃, and 10 ml EG-Bi₂S₃ samples showed the development of nanorods. The 10 ml EG-Bi₂S₃ sample showed better development of nanorods with the addition of ethylene glycol. The agglomeration was considerably reduced with the mixing of solvent. Bi₂S₃, 5 ml EG-Bi₂S₃, and 10 ml EG-Bi₂S₃ catalysts were added to the methylene blue dye solution and its photocatalytic properties were investigated by reducing toxic pollutants under light. The 10 ml EG-Bi₂S₃ sample with neutral pH and 0.1 g of catalyst was added and investigated which showed 86% of efficiency towards dye degradation. The narrow bandgap, defined morphology of 10 ml EG-Bi₂S₃, made a positive result towards efficient photocatalytic activity.

Ultrasensitive detection of cyclin D1 by a self-enhanced ECL immunosensor based on Bi2S3 quantum dots

Bismuth sulfide quantum dots (Bi₂S₃ QDs), which have excellent optical and thermoelectric properties, represent a green and non-toxic semiconductor material that has been widely used in catalysis and photoelectric conversion devices. At present, research on this material has gradually expanded into the biological field. Herein, the biomineralization method mediated by bovine serum albumin (BSA) was utilized to synthesize Bi₂S₃ QDs with monodispersity, excellent colloidal stability, and good biocompatibility. This is the first study on the electrochemiluminescence (ECL) characteristics of Bi₂S₃ QDs and related ECL mechanisms in detail. In addition, on the basis of Bi₂S₃ QDs, an ECL immunosensor was used for the ultrasensitive measurement of cyclin D1 (CCND1). The composite material, namely Au@Cu-Bi₂S₃ QDs was used as a high-sensitivity ECL probe, in which AuNPs were connected with Bi₂S₃ QDs through a copper(ii) ion bridge. PDA-AgNPs made of dopamine (DA) and silver nanoparticles (AgNPs) were utilized as a carrier for fixing the primary antibody (Ab₁), ultimately presenting a relatively wide detection range of 10 fg mL^-1-1 μg mL^-1. Moreover, quite a low detection limit (6.34 fg mL^-1) was also obtained for an assay of CCND1. Results indicated that the immunosensor can provide a potential platform with fine stability and creditable reproducibility for clinical diagnosis.

Morphological variations in Bi2S3 nanoparticles synthesized by using a single source precursor

A simple solvothermal decomposition of bismuth dithiocarbamate complex in oleylamine, oleic acid, and hexadecylamine at 180 °C, yielded bismuth sulphide nanomaterials of different morphologies represented as Bi₂S₃(OAm), Bi₂S₃(OAc) and Bi₂S₃(HDA) respectively. The bismuth complex, used as the single source precursor, was synthesized and characterised by elemental analysis, FTIR, and NMR spectroscopic techniques. The spectroscopic and micro analysis confirmed the proposed compound, while the as-prepared nanoparticles were characterized using UV-visible spectroscopy, X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and energy dispersive spectrometer (EDS). The effects of the different solvent media on the structural properties of the obtained Bi₂S₃ were investigated. An orthorhombic phase bismuthinite of varying intensities were obtained, with an indication that a bias of orientations existed in the (2 1 1) crystallographic planes in the Bi₂S₃(OAm) compared to the characteristic (1 3 0) diffraction peak of Bi₂S₃. The microscopic analysis showed a correlation between the nanoparticles' morphology and the type of solvent used, which also implied that the properties of Bi₂S₃ were affected by the solvent medium.

Millimeter-sized Bi2S3@polyacrylonitrile hybrid beads for highly efficient iodine capture

Chemisorption of iodine by forming BiI₃was the main capturing mechanism of Bi₂S₃@PAN for iodine.

Construction of titanium dioxide/cadmium sulfide heterojunction on carbon fibers as weavable photocatalyst for eliminating various contaminants

Semiconductor heterojunction powders have exhibited the enhanced photocatalytic activities, but their practical applications have been limited due to their poor recycling performance from flowing wastewater. To solve these problems, with carbon fibers (CFs) as the fixing substrate, we constructed TiO₂/CdS heterojunction as a model on CF surface by utilizing a hydrothermal-chemical bath deposition method. CFs/TiO₂/CdS bundles display a wide photoabsorption with two photoabsorption edges (~410 and 520 nm). Furthermore, CFs/TiO₂/CdS bundles can be weaved into macroscopical cloth (such as weight: 0.1 g, area: 4 × 4 cm²) which have considerable photocurrent density of 5.75 × 10^-6 A/cm². Under visible light irradiation (λ > 400 nm), macroscopic CFs/TiO₂/CdS cloth can degrade 95.44% methylene blue (MB), 64.95% acid orange 7 (AO7), 91.37% tetracycline hydrochloride (TC) and remove 90.70% hexavalent chromium (Cr(VI)) after 120 min, higher than those by CFs/CdS (43.42% MB, 37.42% AO7, 31.76% TC and 30.45% Cr(VI)) or CFs/TiO₂ (12.84% MB, 10.48% AO7, 11.85% TC and 15.58% Cr(VI)). Thus, CFs/TiO₂/CdS can act as a weavable and efficient photocatalyst for eliminating various pollutants from wastewater.

Facile Synthesis of Heterojunctioned ZnO/Bi2S3 Nanocomposites for Enhanced Photocatalytic Reduction of Aqueous Cr(VI) under Visible-Light Irradiation

Heterojunctioned ZnO/Bi2S3 nanocomposites were prepared via a facile solvothermal method. The obtained photocatalysts were characterized by X-ray powder diffraction (XRD), Scanning electron microscopy (SEM), High resolution transmission electron microscopy (HRTEM), X-ray photoelectron spectroscopy (XPS), UV-Vis diffuse reflectance spectroscopy (DRS), and Photoelectrochemical and Photoluminescence spectroscopy (PL), respectively. The results showed that ZnO/Bi2S3 composites exhibited the sandwiched-like structure, where ZnO nanoparticles were randomly embedded between Bi2S3 nanoflakes. The performance of photocatalytic Cr(VI) reduction under visible light indicated that ZnO/Bi2S3 composites exhibited high-efficiency photocatalytic activity in comparison with either Bi2S3 or ZnO. The 5%-ZnO/Bi2S3 photocatalyst removed 96% of Cr(VI) within 120 min at 20 mg/L initial concentration of Cr(VI). The enhanced performance of ZnO/Bi2S3 photocatalysts could be ascribed to the increased light harvesting and the effective separation and transfer of the photogenerated charge carriers across the heterojunction interface of the ZnO/Bi2S3 composite. This work could pave the way for the design of new hetero-structured materials and has great potential in environmental remediation.

Review on nanoscale Bi-based photocatalysts

Nanoscale Bi-based photocatalysts are promising candidates for visible-light-driven photocatalytic environmental remediation and energy conversion. However, the performance of bulk bismuthal semiconductors is unsatisfactory. Increasing efforts have been focused on enhancing the performance of this photocatalyst family. Many studies have reported on component adjustment, morphology control, heterojunction construction, and surface modification. Herein, recent topics in these fields, including doping, changing stoichiometry, solid solutions, ultrathin nanosheets, hierarchical and hollow architectures, conventional heterojunctions, direct Z-scheme junctions, and surface modification of conductive materials and semiconductors, are reviewed. The progress in the enhancement mechanism involving light absorption, band structure tailoring, and separation and utilization of excited carriers, is also introduced. The challenges and tendencies in the studies of nanoscale Bi-based photocatalysts are discussed and summarized.

Simultaneous removal of Cr(VI) and phenol contaminants using Z-scheme bismuth oxyiodide/reduced graphene oxide/bismuth sulfide system under visible-light irradiation

An all-solid-state Z-scheme system containing Bi-based semiconductors bismuth oxyiodide (BiOI) and bismuth sulfide (Bi₂S₃) was constructed on reduced graphene oxide (rGO) sheets through an electrostatic self-assembly method to simultaneously remove aqueous Cr(VI) and phenol. In this Z-scheme that mimicked natural photosynthesis, photoinduced electrons in the conduction band (CB) of BiOI were transferred through rGO and reacted with photoinduced holes in the valence band (VB) of Bi₂S₃, which significantly increased its photocatalytic activity. The reduction and oxidation reactions were performed on Bi₂S₃ and BiOI photocatalysts, respectively. Furthermore, complex contaminants of coexisting heavy metal Cr(VI) and organic phenol were treated using the system under visible-light irradiation. Results showed that Cr(VI) reduction and phenol oxidation were achieved efficiently with optimum reductive and oxidative efficiencies up to 73% and 95% under visible-light irradiation, respectively. This work provided a promising method of simultaneously removing heavy metals and organic pollutants by using a Z-scheme system with enhanced photocatalytic activity.

Dahlia-shaped BiOClxI1-x structures prepared by a facile solid-state method: Evidence and mechanism of improved photocatalytic degradation of rhodamine B dye

A rapid and cheap solid-state chemical process was employed to synthesize BiOCl_xI_1-x (x=1.0, 0.75, 0.5, 0.25, 0) solid solutions with dahlia-shaped hierarchitectures. The dahlia-shaped BiOCl_xI_1-x hierarchitectures were effectively constructed by nanoplates with a thickness about 5-13nm. The band gap structure of the solid solutions can be modulated by adjusting the composition ratio of Cl and I, which has a significant effect on the photocatalytic activity of the solid solutions. The dahlia-shaped BiOCl_xI_1-x (x=0.75) solid solution exhibits excellent adsorption and effective photocatalytic performances for rhodamine B (RhB) under visible light irradiation, which degraded more than 98% of RhB within 60min under the visible light irradiation, it is higher than the reported bismuth oxyhalides materials. The trapping experiments confirmed that O^2- and h⁺ played the major role in the photocatalytic process and the possible photocatalytic reaction mechanism was illustrated.