Fabrication of bismuth subcarbonate nanotube arrays from bismuth citrate

Evaluation of the photodegradation activity of bismuth oxoiodide/bismuth sub-carbonate nanocatalyst: Experimental design and the mechanism study

In this study, a binary BiOI/(BiO)2CO3 catalyst was prepared and used for sulfasalazine (SSZ) photodegradation in an aqueous phase. The semiconductors were identified by XRD, SEM-EDX, and UV-Vis diffuse reflectance spectroscopy (DRS) methods. Applying the Kubelka-Munk model on DRS results, the band gap energies of 2.09, 3.5, and 2.07 eV were obtained for BiOI, (BiO)2CO3, and BiOI/(BiO)2CO3 samples. pHpzc values of 6.3, 10.1, and 8.1 were estimated for BiOI, (BiO)2CO3, and BiOI/(BiO)2CO3, respectively. After observing the boosted photocatalytic activity by the coupled system, the interaction effects of the influencing variables in SSZ photodegradation were evaluated via the response surface methodology (RSM) approach. The optimal RSM-run conditions were 8.5 ppm SSZ at pH 8, which contained 0.28 g/L of the BiOI/(BiO)2CO3 catalyst and 29 min illumination time, resulting in 87% SSZ photodegradation. The effects of some scavenging agents were also studied to elucidate the relative roles of the reactive species in the SSZ photodegradation by the proposed catalyst, that is, hydroxyl radicals ∼ photoinduced electrons > superoxide radicals ∼ photoinduced holes. The proposed catalyst retained good activity after 5 successive reusing runs.

Broad-Spectrum Antimicrobial Activity of Ultrafine (BiO)2CO3 NPs Functionalized with PVP That Can Overcome the Resistance to Ciprofloxacin, AgNPs and Meropenem in Pseudomonas aeruginosa

Although it has no known biochemical role in living organisms, bismuth has been used to treat syphilis, diarrhea, gastritis and colitis for almost a century due to its nontoxic nature to mammalian cells. When prepared via a top-down sonication route from a bulk sample, bismuth subcarbonate (BiO)₂CO₃ nanoparticles (NPs) with an average size of 5.35 ± 0.82 nm exhibit broad-spectrum potent antibacterial activity against both the gram-positive and gram-negative bacteria including methicillin-susceptible Staphylococcus aureus (DSSA), methicillin-resistant Staphylococcus aureus (MRSA), drug-susceptible Pseudomonas aeruginosa (DSPA) and multidrug-resistant Pseudomonas aeruginosa (DRPA). Specifically, the minimum inhibitory concentrations (MICs) are 2.0 µg/mL against DSSA and MRSA and 0.75 µg/mL against DSPA and DRPA. In sharp contrast to ciprofloxacin, AgNPs and meropenem, (BiO)₂CO₃ NPs show no sign of developing Bi-resistant phenotypes after 30 consecutive passages. On the other hand, such NPs can readily overcome the resistance to ciprofloxacin, AgNPs and meropenem in DSPA. Finally, the combination of (BiO)₂CO₃ NPs and meropenem shows a synergistic effect with the fractional inhibitory concentration (FIC) index of 0.45.

Metal-Based Nanoparticles: A Prospective Strategy for Helicobacter pylori Treatment

Helicobacter pylori (H. pylori) is an infectious pathogen and the leading cause of gastrointestinal diseases, including gastric adenocarcinoma. Currently, bismuth quadruple therapy is the recommended first-line treatment, and it is reported to be highly effective, with >90% eradication rates on a consistent basis. However, the overuse of antibiotics causes H. pylori to become increasingly resistant to antibiotics, making its eradication unlikely in the foreseeable future. Besides, the effect of antibiotic treatments on the gut microbiota also needs to be considered. Therefore, effective, selective, antibiotic-free antibacterial strategies are urgently required. Due to their unique physiochemical properties, such as the release of metal ions, the generation of reactive oxygen species, and photothermal/photodynamic effects, metal-based nanoparticles have attracted a great deal of interest. In this article, we review recent advances in the design, antimicrobial mechanisms and applications of metal-based nanoparticles for the eradication of H. pylori. Additionally, we discuss current challenges in this field and future perspectives that may be used in anti-H. pylori strategies.

Helicobacter Pylori-Induced Gastric Infections: From Pathogenesis to Novel Therapeutic Approaches Using Silver Nanoparticles

Helicobacter pylori is the first formally recognized bacterial carcinogen and the most important single digestive pathogen responsible for the induction of gastroduodenal diseases such as gastritis, peptic ulcer, and, finally, gastric neoplasia. The recently reported high rates of antimicrobial drug resistance hamper the current therapies of H. pylori, with therapeutic failure reaching up to 40% of patients. In this context, new treatment options and strategies are urgently needed, but the successful development of these new therapeutic tools is conditioned by the understanding of the high adaptability of H. pylori to the gastric acidic environment and the complex pathogenic mechanism. Due to several advantages, including good antibacterial efficiency, possible targeted delivery, and long tissular persistence, silver nanoparticles (AgNPs) offer the opportunity of exploring new strategies to improve the H. pylori therapy. A new paradigm in the therapy of H. pylori gastric infections using AgNPs has the potential to overcome the current medical limitations imposed by the H. pylori drug resistance, which is reported for most of the current organic antibiotics employed in the classical therapies. This manuscript provides an extensive overview of the pathology of H. pylori-induced gastritis, gastric cancer, and extradigestive diseases and highlights the possible benefits and limitations of employing AgNPs in the therapeutic strategies against H. pylori infections.

Combatting Helicobacter pylori with oral nanomedicines

Helicobacter pylori (H. pylori) infection is considered to be the main cause of most digestive diseases,such as chronic active gastritis, gastroduodenal ulcers, or even gastric cancer. Oral medication is a transformative approach to treat H. pylori-induced infections. However, unlike intravenous administration, orally administrated drugs have to overcome various barriers before reaching the infected sites, which significantly limits the therapeutic efficacy. These challenges may be addressed by emerging nanomedicine that is equipped with nanotechnology approaches to enable efficient and effective targeted delivery of drugs. Herein, in this review, we first discuss the conventional therapy for the eradication of H. pylori. Through the introduction of the critical barriers of oral administration, the benefits of nanomedicine are highlighted. Recently-published examples of nanocarriers for combating H. pylori in terms of design, preparation, and antimicrobial mechanisms are then presented, followed by our perspective on potential future research directions of oral nanomedicines.

Medicinal chemistry and biomedical applications of bismuth-based compounds and nanoparticles

Bismuth as a relatively non-toxic and inexpensive metal with exceptional properties has numerous biomedical applications. Bismuth-based compounds are used extensively as medicines for the treatment of gastrointestinal disorders including dyspepsia, gastric ulcers and H. pylori infections. Recently, its medicinal application was further extended to potential treatments of viral infection, multidrug resistant microbial infections, cancer and also imaging, drug delivery and biosensing. In this review we have highlighted the unique chemistry and biological chemistry of bismuth-209 as a prelude to sections covering the unique antibacterial activity of bismuth including a description of research undertaken to date to elucidate key molecular mechanisms of action against H. pylori, the development of novel compounds to treat infection from microbes beyond H. pylori and the significant role bismuth compounds can play as resistance breakers. Furthermore we have provided an account of the potential therapeutic application of bismuth-213 in targeted alpha therapy as well as a summary of the biomedical applications of bismuth-based nanoparticles and composites. Ultimately this review aims to provide the state of the art, highlight the untapped biomedical potential of bismuth and encourage original contributions to this exciting and important field.

Shedding Light on the Role of Chemical Bond in Catalysis of Nitrogen Fixation

Ammonia (NH₃ ) and nitrates are essential for human society because of their widespread utilization for producing medicines, fibers, fertilizers, etc. In recent years, the development on nitrogen fixation under mild reaction conditions has attracted much attention. However, the very low conversion efficiency and ambiguous catalytic mechanism remain the major hurdles for the research of nitrogen fixation. This review aims to clarify the role of chemical bond in catalytic nitrogen fixation by summarizing and analyzing the recent development of nitrogen fixation research. In detail, the atomic-scale mechanism of nitrogen fixation reaction, the various methods to improve the nitrogen fixation performance, and the computational investigation of nitrogen fixation are discussed, all from a chemical bond perspective. It is hoped that this review could trigger more profound pondering and deeper exploration in the field of catalytic nitrogen fixation.

Bismuth-Graphene Nanohybrids: Synthesis, Reaction Mechanisms, and Photocatalytic Applications—A Review

Photocatalysis is a classical solution to energy conversion and environmental pollution control problems. In photocatalysis, the development and exploration of new visible light catalysts and their synthesis and modification strategies are crucial. It is also essential to understand the mechanism of these reactions in the various reaction media. Recently, bismuth and graphene’s unique geometrical and electronic properties have attracted considerable attention in photocatalysis. This review summarizes bismuth-graphene nanohybrids’ synthetic processes with various design considerations, fundamental mechanisms of action, heterogeneous photocatalysis, benefits, and challenges. Some key applications in energy conversion and environmental pollution control are discussed, such as CO2 reduction, water splitting, pollutant degradation, disinfection, and organic transformations. The detailed perspective of bismuth-graphene nanohybrids’ applications in various research fields presented herein should be of equal interest to academic and industrial scientists.

Controlled synthesis of Bi2O2CO3 nanorods with enhanced photocatalytic performance

Bi₂O₂CO₃ nanorod is synthesized via solid–gas high temperature method and exhibits excellent photocatalytic activity for degrading salicylic acid.

Thermal Decomposition of Nanostructured Bismuth Subcarbonate

Nanostructured (BiO)₂CO₃ samples were prepared, and their thermal decomposition behaviors were investigated by thermogravimetric analysis under atmospheric conditions. The method of preparation and Ca²⁺ doping could affect the morphologies of products and quantity of defects, resulting in different thermal decomposition mechanisms. The (BiO)₂CO₃ nanoplates decomposed at 300–500 °C with an activation energy of 160–170 kJ/mol. Two temperature zones existed in the thermal decomposition of (BiO)₂CO₃ and Ca-(BiO)₂CO₃ nanowires. The first one was caused by the decomposition of (BiO)₄(OH)₂CO₃ impurities and (BiO)₂CO₃ with surface defects, with an activation energy of 118–223 kJ/mol, whereas the second one was attributed to the decomposition of (BiO)₂CO₃ in the core of nanowires, with an activation energy of 230–270 kJ/mol for the core of (BiO)₂CO₃ nanowires and 210–223 kJ/mol for the core of Ca-(BiO)₂CO₃ nanowires. Introducing Ca²⁺ ions into (BiO)₂CO₃ nanowires improved their thermal stability and accelerated the decomposition of (BiO)₂CO₃ in the decomposition zone.

A Self-Cleaning Heterostructured Membrane for Efficient Oil-in-Water Emulsion Separation with Stable Flux

Lack of clean water is a major global challenge. Membrane separation technology is an ideal choice for the treatment of industrial, domestic sewage owing to its low energy consumption and cost. However, membranes are highly susceptible to contamination, particularly during wastewater treatment, which has limited their practical applications in this field. Similarly, the flux of the membrane decreases with prolonged use due to its reduced interlayer spacing. Preparation of membranes with anticontamination properties and stable flux is the key to addressing this problem. In this study, a 2D heterostructure membrane with visible-light-driven self-cleaning performance is prepared via a self-assembly process. Notably, the addition of palygorskite increases the interlayer spacing of the graphene and heterojunction structures, which increases the flux of the membrane and avoids a decrease of the interlayer spacing of the membrane under pressure. The presence of a heterojunction with visible light catalytic properties effectively avoids membrane fouling and avoids a sharp decrease of the permeation flux. Importantly, the prepared 2D membrane has excellent separation performance for oil-water emulsions with both high flux and efficiency. These features suggest great potential for the prepared 2D membrane in wastewater treatment applications.

(002) Oriented Bi2O2CO3 Nanosheets with Enhanced Photocatalytic Performance for Toluene Removal in Air

Layer-structured Bi2O2CO3 is a novel photocatalyst for eliminating environmental pollutants. In this work, Bi2O2CO3 nanosheets were synthesized by hydrothermal methods, followed by annealing in nitrogen. (002) oriented Bi2O2CO3 nanosheets were obtained and characterized by XRD, SEM, XPS, BET and UV-Vis diffuse reflectance spectra. Photocatalytic properties were investigated by toluene removal in air, with the assistant of Bi2O2CO3 nanosheets under artificial irradiation. Our results show that Bi2O2CO3 annealed in nitrogen exhibited high full-light-driven photocatalytic activity for toluene photocatalytic decomposition, which may be ascribed to facet orientation evolution during the annealing process and enhanced efficient charge separation. The sample annealed at 150 °C for 8 h (BOC-150-8 h) showed high stability and the highest toluene removal rate, which was up to 99%. The final degradation products were detected by gas chromatography–mass spectrometer (GC-MS) and CO2 was verified to be the primary product. Photocatalytic mineralization of toluene in air over Bi2O2CO3 was proposed. This work may provide a foundation for application of annealed Bi2O2CO3 in indoor air purification.

Eradication of Helicobacter pylori: the power of nanosized formulations

Helicobacter pylori is a pathogen that is considered to cause several gastric disorders such as chronic gastritis, peptic ulcer and even gastric carcinoma. The current therapeutic regimens mainly constitute of a combination of several antimicrobial agents and proton pump inhibitors. However, the prevalence of antibiotic resistance has been significantly lowering the cure rates over the years. Nanocarriers possess unique strengths in this regard owing to the fact that they can protect the drugs (such as antibiotics) from the harsh environment in the stomach, penetrate the mucosal barrier and deliver drugs to the desired site. In this review we summarized recent studies of different antibacterial agents orally delivered by nanosized carriers for the eradication of H. pylori.

The versatile biomedical applications of bismuth-based nanoparticles and composites: therapeutic, diagnostic, biosensing, and regenerative properties

Studies of nanosized forms of bismuth (Bi)-containing materials have recently expanded from optical, chemical, electronic, and engineering fields towards biomedicine, as a result of their safety, cost-effective fabrication processes, large surface area, high stability, and high versatility in terms of shape, size, and porosity. Bi, as a nontoxic and inexpensive diamagnetic heavy metal, has been used for the fabrication of various nanoparticles (NPs) with unique structural, physicochemical, and compositional features to combine various properties, such as a favourably high X-ray attenuation coefficient and near-infrared (NIR) absorbance, excellent light-to-heat conversion efficiency, and a long circulation half-life. These features have rendered bismuth-containing nanoparticles (BiNPs) with desirable performance for combined cancer therapy, photothermal and radiation therapy (RT), multimodal imaging, theranostics, drug delivery, biosensing, and tissue engineering. Bismuth oxyhalides (BiO_x, where X is Cl, Br or I) and bismuth chalcogenides, including bismuth oxide, bismuth sulfide, bismuth selenide, and bismuth telluride, have been heavily investigated for therapeutic purposes. The pharmacokinetics of these BiNPs can be easily improved via the facile modification of their surfaces with biocompatible polymers and proteins, resulting in enhanced colloidal stability, extended blood circulation, and reduced toxicity. Desirable antibacterial effects, bone regeneration potential, and tumor growth suppression under NIR laser radiation are the main biomedical research areas involving BiNPs that have opened up a new paradigm for their future clinical translation. This review emphasizes the synthesis and state-of-the-art progress related to the biomedical applications of BiNPs with different structures, sizes, and compositions. Furthermore, a comprehensive discussion focusing on challenges and future opportunities is presented.

Synthesis and Characterization of a New Aluminum-Doped Bismuth Subcarbonate

A new compound, Bi2O2CO3:Al, was synthesized by the coprecipitation method. The characterization was done by X-ray diffraction (XRD), Fourier transformed infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), electronic scanning microscopy (SEM), and energy dispersive X-ray spectroscopy (EDX). The characterization methods allowed to identify the Bi2O2CO3:Al compound, such as the Al-doped Bi2O2CO3 by XRD, the anionic part (CO32−) by FTIR, and the presence of aluminum in the compound by XPS and EDX. It was confirmed to have a nanostructure like a nanosheet and a microstructure that resembles a type sponge by SEM.

Facet-dependent photocatalytic NO conversion pathways predetermined by adsorption activation patterns

Photocatalysts with different exposed facets generally exhibit different physicochemical properties, but the underlying mechanism has not been revealed. In this study, we synthesized nanoflake-assembled flower-like Bi2O2CO3 and homodisperse nanoflakes Bi2O2CO3 with exposed {110} and {001} facets (110-BOC and 001-BOC), respectively, to probe the activation and reaction mechanism of facet-dependent reactants. The results showed that Bi2O2CO3 with exposed {001} facets exhibited superior photocatalytic activity for photocatalytic abatement of NO in the air in comparison with 110-BOC. According to the combined results of ESR spectra and DFT calculation, the superior photocatalytic activity of 001-BOC stemmed from its enhanced capability to activate the reactants (O2 and H2O), which facilitated the formation of reactive radicals to participate in the photocatalytic NO oxidation. Most significantly, the time-dependent in situ DRIFTS spectra and DFT simulation results reveal that the adsorption activation of pollutants and desorption mechanisms of products were different for 110-BOC and 001-BOC in photocatalytic NO oxidation. Due to the differences in the atomic arrangement on the {110} and {001} facets, 001-BOC enabled the transformation of NO into NO- or cis-N2O22- during adsorption activation, while 110-BOC induces the adsorption activation of NO into NO+ or N2O3. The {001} facet of Bi2O2CO3 could promote the oxidation of intermediates to final products (NO3-) and enhance NO3- desorption. These different adsorption activation patterns on {110} and {001} facets essentially predetermined the facet-dependent conversion pathways of photocatalytic NO oxidation on different facets. The findings of this work would have critical implications for the understanding of the facet-dependent reaction mechanism and the design of novel efficient catalysts.

Bismuth Subcarbonate with Designer Defects for Broad-Spectrum Photocatalytic Nitrogen Fixation

A facial hydrothermal method is applied to synthesize bismuth subcarbonate (Bi₂O₂CO₃, BOC) with controllable defect density (named BOC- X) using sodium bismuthate (NaBiO₃) and graphitic carbon nitride (GCN) as precursors. The defects of BOC- X may originate from the extremely slow decomposition of GCN during the hydrothermal process. The BOC- X with optimal defect density shows a photocatalytic nitrogen fixation amount of 957 μmol L^-1 under simulated sunlight irradiation within 4 h, which is 9.4 times as high as that of pristine BOC. This superior photocatalytic performance of BOC- X is attributed to the surface defect sites. These defects in BOC- X contribute to a defect level in the forbidden band, which extends the light-harvest region of the photocatalyst from the ultraviolet to the visible-light region. Besides, surface defects prevent electron-hole recombination by accommodating photogenerated electrons in the defect level to promote the separation efficiency of charge carrier pairs. This work not only demonstrates a novel and scalable strategy to synthesize defective Bi₂O₂CO₃ but also presents a new perspective for the synthesis of photocatalysts with controllable defect density.

β-Bi2O3 reduction by laser irradiation in a liquid environment

This study reports the structural and stoichiometric modifications of bismuth oxide nanoparticles in the β phase (β-Bi₂O₃) by UV pulsed laser irradiation in water or ethanol solutions.

Bi2O2CO3 Growth at Room Temperature: In Situ X-ray Diffraction Monitoring and Thermal Behavior

The room-temperature formation of bismuth oxycarbonate (Bi₂O₂CO₃) from Bi₂O₃ in sodium carbonate buffer was investigated with in situ powder X-ray diffraction (PXRD) in combination with electron microscopy and vibrational spectroscopy. Time-resolved PXRD measurements indicate a pronounced and rather complex pH dependence of the reaction mechanism. Bi₂O₂CO₃ formation proceeds within a narrow window between pH 8 and 10 via different mechanisms. Although a zero-dimensional nucleation model prevails around pH 8, higher pH values induce a change toward a diffusion-controlled model, followed by a transition to regular nucleation kinetics. Ex situ synthetic and spectroscopic studies confirm these trends and demonstrate that in situ monitoring affords vital parameter information for the controlled fabrication of Bi₂O₂CO₃ materials. Furthermore, the β → α bismuth oxide transformation temperatures of Bi₂O₂CO₃ precursors obtained from different synthetic routes differ notably (by min 50 °C) from commercially available bismuth oxide. Parameter studies suggest a stabilizing role of surface carbonate ions in the as-synthesized bismuth oxide sources. Our results reveal the crucial role of multiple preparative history parameters, especially of pH value and source materials, for the controlled access to bismuth oxide-based catalysts and related functional compounds.

The Preparation of a Highly Efficient Ag3PO4/Ag/Bi2O2CO3 Photo-Catalyst and the Study of Its Photo-Catalytic Organic Synthesis Reaction Driven by Visible Light

Ag3PO4/Ag/Bi2O2CO3 composites were prepared by a hydrothermal and precipitation method. The morphology, structure, and valence state of the photo-catalysts were characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), Scanning electron microscopy (SEM), Brunauer-Emmett-Teller (BET) specific surface areas, and UV-vis diffuse reflectance spectra (UV-vis DRS). They were applied as heterogeneous catalysts in the synthesis of esters from aldehydes (or alcohols) and alcohols and the synthesis of imines from alcohols and amines under visible light irradiation. The photo-catalytic activities of the esterification reactions of aldehydes and alcohols were heavily dependent on the loading of Ag3PO4/Ag/Bi2O2CO3 as well as the intensity and wavelength of the visible light. Furthermore, their conversion under visible light irradiation was superior to that in the dark. Herein a reaction mechanism from aldehydes and alcohols to esters was proposed, and the Ag3PO4/Ag/Bi2O2CO3 catalysts could be used six times without a significant decrease in activity. Using these catalysts under visible light could motivate future studies to develop efficient recyclable photo-catalysts and facilitate many synthetic organic reactions.

Fe(Ⅲ) ions enhanced catalytic properties of (BiO)2CO3 nanowires and mechanism study for complete degradation of xanthate

The wire-like Fe³⁺-doped (BiO)₂CO₃ photocatalyst was synthesized by a hydrothermal method. The photocatalytic property of Fe³⁺-doped (BiO)₂CO₃ nanowires was evaluated through degradation of sodium isopropyl xanthate under UV-visible light irradiation. The as-prepared Fe³⁺-doped (BiO)₂CO₃ nanowires were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), UV-visible diffuse reflectance spectroscopy (UV-vis DRS), X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared spectroscopy (FTIR) in detail. The results of XRD showed that the crystallinity of (BiO)₂CO₃ nanowires decreased when Fe³⁺ ions were introduced into the solution system. XPS results illustrated that xanthate could be absorbed on the surface of Fe³⁺-doped (BiO)₂CO₃ nanowires to produce BiS bond at the beginning of the reaction, which could broaden the visible light absorption. FTIR spectra confirmed the formation of SO₄^2- after photocatalytic decomposition of xanthate solution. The Fe³⁺-doped (BiO)₂CO₃ nanowires showed an enhanced photocatalytic activity for decomposition of xanthate due to the narrower band gap and larger BET surface area, comparing with pure (BiO)₂CO₃ nanowires. By the results of UV-vis spectra of the solution and FTIR spectra of recycled Fe³⁺-doped (BiO)₂CO₃, the xanthate was oxidized completely into CO₂ and SO₄^2-. The photocatalytic degradation process of xanthate followed a pseudo-second-order kinetics model. The mechanism of enhanced photocatalytic activity was proposed as well.

Br-Doped Bi2O2CO3 exposed (001) crystal facets with enhanced photocatalytic activity

Br-Doped Bi₂O₂CO₃ exposed (001) facets were synthesized using CTAB as a surfactant and dopant. The highly enhanced photocatalytic performance of Br-doped Bi₂O₂CO₃ is attributed to the synergistic effects of the doping of Br⁻ and the active exposed (001) crystal facet.

Surface oxygen vacancy induced solar light activity enhancement of a CdWO4/Bi2O2CO3 core–shell heterostructure photocatalyst

A CdWO₄/Bi₂O₂CO₃ core–shell heterostructure photocatalyst was fabricated via a facile two-step hydrothermal process.

Enhanced Visible Light Photocatalytic Degradation of Organic Pollutants over Flower-Like Bi₂O₂CO₃ Dotted with Ag@AgBr

A facile and feasible oil-in-water self-assembly approach was developed to synthesize flower-like Ag@AgBr/Bi₂O₂CO₃ micro-composites. The photocatalytic activities of the samples were evaluated through methylene blue degradation under visible light irradiation. Compared to Bi₂O₂CO₃, flower-like Ag@AgBr/Bi₂O₂CO₃ micro-composites show enhanced photocatalytic activities. In addition, results indicate that both the physicochemical properties and associated photocatalytic activities of Ag@AgBr/Bi₂O₂CO₃ composites are shown to be dependent on the loading quantity of Ag@AgBr. The highest photocatalytic performance was achieved at 7 wt % Ag@AgBr, degrading 95.18% methylene blue (MB) after 20 min of irradiation, which is over 1.52 and 3.56 times more efficient than that of pure Ag@AgBr and pure Bi₂O₂CO₃, respectively. Bisphenol A (BPA) was also degraded to further demonstrate the degradation ability of Ag@AgBr/Bi₂O₂CO₃. A photocatalytic mechanism for the degradation of organic compounds over Ag@AgBr/Bi₂O₂CO₃ was proposed. Results from this study illustrate an entirely new approach to fabricate semiconductor composites containing Ag@AgX/bismuth (X = a halogen).

Facile synthesis of surface N-doped Bi2O2CO3: Origin of visible light photocatalytic activity and in situ DRIFTS studies

Bi2O2CO3 nanosheets with exposed {001} facets were prepared by a facile room temperature chemical method. Due to the high oxygen atom density in {001} facets of Bi2O2CO3, the addition of cetyltrimethylammonium bromide (CTAB) does not only influence the growth of crystalline Bi2O2CO3, but also modifies the surface properties of Bi2O2CO3 through the interaction between CTAB and Bi2O2CO3. Nitrogen from CTAB as dopant interstitially incorporates in the Bi2O2CO3 surface evidenced by both experimental and theoretical investigations. Hence, the formation of localized states from NO bond improves the visible light absorption and charge separation efficiency, which leads to an enhancement of visible light photocatalytic activity toward to the degradation of Rhodamine B (RhB) and oxidation of NO. In addition, the photocatalytic NO oxidation over Bi2O2CO3 nanosheets was successfully monitored for the first time using in situ diffuse reflectance infrared Fourier-transform spectroscopy (DRIFTS). Both bidentate and monodentate nitrates were identified on the surface of catalysts during the photocatalytic reaction process. The application of this strategy to another relevant bismuth based photocatalyst, BiOCl, demonstrated that surface interstitial N doping could also be achieved in this case. Therefore, our current route seems to be a general option to modify the surface properties of bismuth based photocatalysts.

Fabrication of hierarchically structured novel redox-mediator-free ZnIn2S4 marigold flower/Bi2WO6 flower-like direct Z-scheme nanocomposite photocatalysts with superior visible light photocatalytic efficiency

Efficient direct Z-scheme ZnIn₂S₄ marigold flower/Bi₂WO₆ flower photocatalyst for the degradation of metronidazole pharmaceutical under visible-light irradiation.

Synthesis of morphology-controlled bismutite for selective applications

Bismutite (Bi₂O₂CO₃) possessing diverse morphologies, namely, nanosheets, nanodiscs and nanoplatelets, was synthesized by a simple controllable method shows excellent materials as adsorbents and photocatalysts for wastewater treatment with supercapacitor activities for energy applications.

Single step hydrothermal synthesis of beyerite, CaBi2O2(CO3)2 for the fabrication of UV-visible light photocatalyst BiOI/CaBi2O2(CO3)2

Uniform rectangular plates of the mineral, beyerite (CaBi₂O₂(CO₃)₂) belonging to the “sillen” family have been successfully synthesized and is used in fabricating the composite photocatalyst BiOI/CaBi₂O₂(CO₃)₂.

Mild synthesis of {001} facet predominated Bi2O2CO3 clusters with outstanding simulated sunlight photocatalytic activities

Bi₂O₂CO₃ clusters built up of ultrathin nanosheets with predominated {001} facets were facilely synthesized via a template-free hydrothermal strategy at a mild temperature of 60 °C and exhibit excellent photocatalytic activity.

In situ decoration of plasmonic Ag nanocrystals on the surface of (BiO)2CO3 hierarchical microspheres for enhanced visible light photocatalysis

Novel plasmonic 0D Ag nanocrystal decorated 3D (BiO)2CO3 hierarchical microspheres were fabricated with a one-pot hydrothermal method. The as-prepared samples were systematically characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, N2 adsorption-desorption isotherms, X-ray photoelectron spectroscopy, UV-vis diffuse reflectance spectroscopy, photoluminescence spectra, ns-level time-resolved fluorescence spectra, photocurrent generation and EIS measurement. The results indicated that the 0D Ag nanoparticles were deposited on the surface of 3D (BiO)2CO3 hierarchical microspheres. The deposited Ag nanoparticles were reduced from Ag(+) by the citrate ions from bismuth citrate. The photocatalytic activity of the as-prepared samples was evaluated towards the degradation of NO at ppb-level under visible light irradiation. The intermediate NO2 was monitored on-line during the photocatalytic reaction. The pure (BiO)2CO3 microspheres exhibited decent visible light photocatalytic activity because of the surface scattering and reflecting (SSR effect) resulting from the special 3D hierarchical architecture. The Ag-decorated (BiO)2CO3 microspheres (Ag/BOC) exhibited greatly enhanced photocatalytic activity, photocurrent generation and promoted NO2 oxidation compared to the pure (BiO)2CO3 microspheres. The enhanced photocatalytic activity and photocurrent generation of Ag/BOC was ascribed to the cooperative contribution of the surface plasmon resonance (SPR effect), efficient separation of electron-hole pairs and prolonged lifetime of charge carriers induced by Ag nanoparticles. The photocatalytic performance of Ag/BOC was dependent on the content of Ag loading. When the amount of Ag is controlled at 5%, the highest photocatalytic performance can be achieved. Further increasing the Ag loading content promotes aggregation of the Ag particles and transforms the uniform microspheres into non-uniform microspheres, which is not beneficial to improving the activity. Importantly, the as-prepared Ag/BOC composites exhibited high photochemical stability after multiple reaction runs. The concepts of enhancing the activity through the SSR and SPR effects provide a new avenue for the development of efficient noble metal/bismuth-based plasmonic photocatalysts with attractive nano/micro architectures for efficient visible light photocatalytic activity.

Synthesis and properties of visible light responsive g-C3N4/Bi2O2CO3 layered heterojunction nanocomposites

A g-C₃N₄/Bi₂O₂CO₃ layered heterojunction nanocomposite exhibits more effective separation of photogenerated electron–hole pairs and a stable chemical structure, thus showing higher photocatalytic activity and stability.

In situ growth of Au nanoparticles on 3D Bi2O2CO3 for surface plasmon enhanced visible light photocatalysis

The highly visible light active 3D Au/Bi₂O₂CO₃ heterostructure was fabricated by a one-pot in situ hydrothermal method.

Mechanism of visible light photocatalytic NOx oxidation with plasmonic Bi cocatalyst-enhanced (BiO)2CO3 hierarchical microspheres

The visible light photocatalysis mechanism is revealed for plasmonic Bi cocatalyst-enhanced (BiO)₂CO₃ hierarchical microspheres developed by a solvent-controlled strategy.