Fabrication of Novel g-C3N4@Bi/Bi2O2CO3 Z-Scheme Heterojunction with Meliorated Light Absorption and Efficient Charge Separation for Superior Photocatalytic Performance

Herein, a novel g-C₃N₄@Bi/Bi₂O₂CO₃ Z-scheme heterojunction was synthesized via simple methods. UV/Vis diffuse reflectance spectroscopy (DRS) revealed that the visible light absorption range of heterojunction composites was broadened from 400 nm to 500 nm compared to bare Bi₂O₂CO₃. The XRD, XPS and TEM results demonstrated that metal Bi was introduced into g-C₃N₄@Bi/Bi₂O₂CO₃ composites, and Bi may act as an electronic bridge in the heterojunction. Metal Bi elevated the separation efficiency of carriers, which was demonstrated by photocurrent and photoluminescence. The performance of samples was assessed via the degradation of Rhodamine B (RhB), and the results exhibited that g-C₃N₄@Bi/Bi₂O₂CO₃ possessed notably boosted photocatalytic activity compared with g-C₃N₄, Bi₂O₂CO₃ and other binary composites. The heterojunction photocatalysts possessed good photostability and recyclability in triplicate cycling tests. Radical trapping studies identified that h⁺ and •O₂^- were two primary active species during the degradation reaction. Based on the energy band position and trapping radical experiments, the possible reaction mechanism of the indirect Z-scheme heterojunction was also proposed. This work could provide an effective reference to design and establish a heterojunction for improving the photocatalytic activity of Bi₂O₂CO₃.

Visible-light-driven photocatalytic degradation of ofloxacin by BiOBr nanocomposite modified with oxygen vacancies and N-doped CQDs: Enhanced photodegradation performance and mechanism

The rapid recombination of photogenerated carriers and weak light absorption capacity are two major challenges for bismuth-based photocatalysts. Here, N-CQDs/BiO_1-xBr micro-flower photocatalysts with the visible-light activity were fabricated through the ethylene glycol solvothermal method for the first time, and oxygen vacancies (OVs) and N-doped carbon quantum dots (N-CQDs) were simultaneously introduced on the surface of BiOBr. OVs were introduced to form defective BiOBr (BiO_1-xBr). N-CQDs and BiO_1-xBr formed a strong binding effect. Then, the composition, morphology, crystal structure and photoelectric property of photocatalysts were studied, and the mechanism and pathway of ofloxacin (OFL) photodegradation were studied. N-CQDs/BiO_1-xBr-4 was a micro-flower composed of nanosheets with a thickness of about 60 nm, this structure produced multiple light reflections. Photoelectrochemical analysis confirmed that the synergistic effect of OVs and N-CQDs significantly promoted the electron-hole separation (3 times vs BiOBr) and enhanced the light absorption range (Eg = 2.96 eV vs 3.24 eV). Meanwhile, the removal rate of OFL by N-CQDs/BiO_1-xBr-4 was 6 times higher than that by BiOBr (K_obs of N-CQDs/BiO_1-xBr-4 was 32 times higher than that of BiOBr). Electron spin resonances analysis and radical quenching experiments showed that ·O₂^- and h⁺ played dominant roles in the OFL photodegradation system, and their contribution rates were 89.84% and 70.31%, respectively. There were main degradation pathways for OFL, including oxidation, dealkylation, hydroxylation and decarboxylation. This study explored the synergistic and complementary effects between OVs and N-CQDs, and provided a promising strategy for the photodegradation of toxic antibiotics by visible-light-driven photocatalysts.

Structural, Optical and Photocatalytic Activity of Multi-heterojunction Bi2O3/Bi2O2CO3/(BiO)4CO3(OH)2 Nanoflakes Synthesized via Submerged DC Electrical Discharge in Urea Solution

In this research, a novel ternary multi-heterojunction Bi2O3/Bi2O2CO3/(BiO)4CO3(OH)2 photocatalyst is fabricated via submerged DC electrical arc discharge in urea solution. FT-IR, XRD, EDS and PL results confirm the formation of Bi2O3/Bi2O2CO3/(BiO)4CO3(OH)2 multi-heterojunction. Formation of nanoflake morphology is revealed by FE-SEM and TEM images. The optical properties and intense absorption edge of Bi2O3/Bi2O2CO3/(BiO)4CO3(OH)2 reveal the proper visible light absorbing ability. The photocatalytic performance of the sample is investigated via the degradation of methylene orange (MeO) and rhodamine B (RB) under visible light irradiation. The photocatalytic activity of Bi2O3/Bi2O2CO3/(BiO)4CO3(OH)2 is compared with the synthesized sample in water, Bi2O3/Bi/Bi(OH)3, which exhibits much higher photocatalytic activity. Also, the stable photodegradation efficiency of Bi2O3/Bi2O2CO3/(BiO)4CO3(OH)2 after four cycles reveals the long-term stability and reusability of the synthesized photocatalyst. The PL intensity of Bi2O3/Bi2O2CO3/(BiO)4CO3(OH)2 shows an improved separation rate of electron-hole pairs and so enhanced photocatalytic performance. The improved photocatalytic activity can be ascribed to the formation of multi-heterojunctions, flake morphology and intrinsic internal electric field (IEF). Multi-heterojunction nanoflakes enhance the absorbance of visible light and facilitate the separation and transport of photogenerated electron holes through large IEF. Our work offers an effective method for the production of innovative bismuth-based photocatalyst with excellent prospects for the degradation of environmental pollutants and light harvesting for renewable energy generation under visible light.

Optimized strategies for (BiO)2CO3 and its application in the environment

Photocatalysis is a new type of technology, which has been developed rapidly for solving environmental problems such as wastewater or air pollutants in recent years. Also, the effective performance and non-secondary pollution of photocatalytic technology attract much attention from researchers. As a "sillén" phase oxide, the (BiO)₂CO₃ (BOC) is a great potential photocatalyst attributing to composed of alternate Bi₂O₂²⁺ and CO₃^2- layers, which is a benefit for transportation of electrons. Besides, BOC has attracted much attention from researchers because of its excellent characters of non-toxic, environmentally friendly, and low-cost. However, BOC has a defect on wide band gap, which is limited for the usage of visible light, so a great number of published papers focus on the modifications of BOC to improve its photocatalytic efficiency. This article mainly summarizes the modifications of BOC and its application in the environment, guiding for designing BOC-based materials with high photocatalytic activity driven by light. Moreover, the research trend and prospect of BOC photocatalyst were briefly summarized, which could lay the foundation for forming a green and efficient BOC-based photocatalytic reaction system. Importantly, this review might provide a theoretical basis and guidance for further research in this field.

1D/2D constructed Bi2S3/Bi2O2CO3 direct Z-Scheme heterojunction: A versatile photocatalytic material for boosted photodegradation, photoreduction and photoelectrochemical detection of water-based contaminants

In this work, two-dimensional Bi₂O₂CO₃ disk is synthesized, followed by the growth of Bi₂S₃ over Bi₂O₂CO₃ via topotactic transformation by controlling the amount of thiourea under hydrothermal conditions. The synthesized composite catalyst is investigated for photocatalytic oxidation and reduction of tetracycline hydrochloride and hexavalent chromium under visible light irradiation. High interfacial contact between the Bi₂O₂CO₃ disk0 and Bi₂S₃ fiber is confirmed via high-resolution microscopic imaging. Enhanced light absorption and increased charge carrier separation is observed after the formation of the Bi₂S₃/Bi₂O₂CO₃ composite. The Bi₂S₃/Bi₂O₂CO₃ composite grown using 1 mmol of thiourea shows approximately 98% degradation of tetracycline hydrochloride after 120 min and 99% Cr(VI) reduction after 90 min of photochemical reaction under visible light irradiation. The charge separation is due to the formed internal electric field at the interface, which upon light irradiation follows a z-scheme charge transfer hindering the recombination at the Bi₂S₃ and Bi₂O₂CO₃ interface, thereby contributing efficiently to the photochemical process. In addition, the mechanism of the photochemical reaction for the degradation of pollutants is supported using quencher and probe experiments. Furthermore, photoelectrochemical detection of antibiotic in aqueous solution is conducted to understand the sensing feasibility of the synthesized system.

Construction of Bi2O2CO3/Ti3C2 heterojunctions for enhancing the visible-light photocatalytic activity of tetracycline degradation

Bi₂O₂CO₃ (BOC) was successfully loaded on a highly conductive Ti₃C₂ surface by the hydrothermal method, forming a unique BOC/Ti₃C₂ heterostructure. The use of advanced characterization methods reveals the composition, morphology and photoelectric properties of the material. The results show that the interface formed by close contact between BOC and Ti₃C₂ provides an effective channel for charge transfer between the two. Importantly, the photocatalytic degradation efficiency of BOC/Ti₃C₂ for tetracycline (TC) is ~80%, which is significantly higher than the degradation efficiency of pure BOC and pure Ti₃C₂ for TC. In addition, BOC/Ti₃C₂ still has high catalytic activity in the degradation of complex mixed antibiotics. This is because BOC and Ti₃C₂ have large specific surface areas, high light absorption capacity and efficient carrier separation after recombination. At the same time, the detected superoxide radicals (O^2-) and holes (h⁺) are the main active substances. The degradation pathway and catalytic mechanism of the photocatalytic degradation of TC by BOC/Ti₃C₂ are further explained. This research designed and developed a BOC/Ti₃C₂ composite material for the photocatalytic degradation of tetracycline and mixed antibiotic wastewater, providing experimental methods and ideas for actual wastewater treatment.

Hierarchical Bi2O2CO3 wrapped with modified graphene oxide for adsorption-enhanced photocatalytic inactivation of antibiotic resistant bacteria and resistance genes

There is growing pressure for wastewater treatment plants to mitigate the discharge of antibiotic resistant bacteria (ARB) and extracellular resistance genes (eARGs), which requires technological innovation. Here, hierarchical Bi₂O₂CO₃ microspheres were wrapped with nitrogen-doped, reduced graphene oxide (NRGO) for enhanced inactivation of multidrug-resistant E. coli NDM-1 and degradation of the plasmid-encoded ARG (bla_NDM-1) in secondary effluent. The NRGO shell enhanced reactive oxygen species (ROS) generation (•OH and H₂O₂) by about three-fold, which was ascribed to broadened light absorption region (red-shifted up to 459 nm) and decreased electron-transfer time (from 55.3 to 19.8 ns). Wrapping enhanced E. coli adsorption near photocatalytic sites to minimize ROS scavenging by background constituents, which contributed to the NRGO-wrapped microspheres significantly outperforming commercial TiO₂ photocatalyst. ROS scavenger tests indicated that wrapping also changed the primary inactivation pathway, with photogenerated electron holes and surface-attached hydroxyl radicals becoming the predominant oxidizing species with wrapped microspheres, versus free ROS (e.g., •OH, H₂O₂ and •O₂^-) for bare microspheres. Formation of resistance plasmid-composited microsphere complexes, primary due to the π-π stacking and hydrogen bonding between the shell and nucleotides, also minimized ROS scavenging and kept free plasmid concentrations below 10² copies/mL. As proof-of-concept, this work offers promising insight into the utilization of NRGO-wrapped microspheres for mitigating antibiotic resistance propagation in the environment.

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.

Surface-defect-engineered photocatalyst for nitrogen fixation into value-added chemical feedstocks

Surface-defect-engineered photocatalyst for nitrogen fixation.

Polymeric graphitic carbon nitride (g-C3N4)-based semiconducting nanostructured materials: Synthesis methods, properties and photocatalytic applications

In recent years, various facile and low-cost methods have been developed for the synthesis of advanced nanostructured photocatalytic materials. These catalysts are required to mitigate the energy crisis, environmental deterioration, including water and air pollution. Among the various semiconductors explored, recently novel classes of polymeric graphitic carbon nitride (g-C₃N₄)-based heterogeneous photocatalysts have established much greater importance because of their unique physiochemical properties, large surface area, low price, and long service life, ease of synthesis, product scalability, controllable band gap properties, low toxicity, and high photocatalytic activity. The present comprehensive review focuses on recent achievements in a number of facile chemical synthesis methods for semiconducting polymeric carbon nitrides and their heterogeneous nanohybrids with various dopants, nanostructured metals, metal oxides, and nanocarbons, as well as the parameters influencing their physiochemical properties and photocatalytic efficiency, which are discussed with reference to various catalytic applications such as air (NO_x) purification, wastewater treatment, hydrogen generation, CO₂ reduction, and chemical transformation. The mechanisms for the superior photocatalytic activity of polymeric g-C₃N₄-based heterogeneous photocatalysts are also discussed. Finally, the challenges, prospects, and future directions for photocatalytic polymeric g-C₃N₄-based semiconducting materials are described.

AgBr/(Sr0.6Bi0.305)2Bi2O7 Heterostructured Composites: Fabrication, Characterization, and Significantly Enhanced Photocatalytic Activity

The pyrochlore-type (Sr0.6Bi0.305)2Bi2O7 (SBO) containing Bi3+ and Bi5+ mixed valent states was first investigated as a photocatalyst in our very recent work. To further improve the photocatalytic performance, AgBr/SBO heterostructured composites were synthesized by using a deposition-precipitation method. The characterization of phase structure, morphology, microstructure, elemental composition, and optical properties of the obtained products were performed using X-ray diffractometer (XRD), field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM)TEM, X-ray photoelectron spectroscopy (XPS), UV-visible diffuse reflectance spectroscopy (UV-vis DRS). The photocatalytic activity of samples was evaluated by degrading methylene blue under visible light illumination. AgBr/SBO composites possess high stability and significantly enhanced photocatalytic performance. The improvement of photocatalytic activity is due to the enhanced light absorption and the separation of photoinduced electrons and holes on the interface of AgBr/SBO heterostructured composites.

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.

Visible-light photocatalytic capability and the mechanism investigation of a novel PANI/Sn3O4 p–n heterostructure

A novel polyaniline (PANI)/Sn₃O₄ heterojunction composed of PANI nanofibers and Sn₃O₄ nanosheets was fabricated by a facile physical milling technique. Modification of Sn₃O₄ with a PANI conductive polymer contributes to facilitating interfacial charge transfer efficiency, and thus, significantly enhances the visible-light Rhodamine B (RhB) photo-degradation. Results indicate that PANI/Sn₃O₄ heterostructures with 10 wt% PANI reached the maximum degradation efficiency (around 97%) for RhB within 5 h, which is 2.27 times higher than that of Sn₃O₄ alone. This improvement is due to the p–n heterostructure formation in PANI/Sn₃O₄. Moreover, the outcome of reactive species capturing experiments demonstrated that in PANI/Sn₃O₄, holes made the largest contribution to RhB degradation under visible light illumination, while hydroxyl radicals showed less significance under the same conditions. In addition, the photocatalytic mechanism was proposed based on evidence from the reactive species test and energy band structure analysis.

A novel polyaniline (PANI)/Sn₃O₄ heterojunction composed of PANI nanofibers and Sn₃O₄ nanosheets was fabricated by a facile physical milling technique.

Novel hierarchical Sn3O4/BiOX (X = Cl, Br, I) p–n heterostructures with enhanced photocatalytic activity under simulated solar light irradiation

Sn₃O₄/BiOX (X = Cl, Br, I), a series of p–n-heterojunction-based photocatalysts, were prepared by a combination of an ultrasonic-assisted precipitation–deposition method and hydrothermal method.

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.

A porous hierarchical micro/nano LiNi0.5Mn1.5O4 cathode material for Li-ion batteries synthesized by a urea-assisted hydrothermal method

The U/TM ratio has a significant influence on the phase composition, particle morphology and size of the carbonate precursor, thus leading to different electrochemical properties of the LiNi_0.5Mn_1.5O₄ material.

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.

An ion-exchange strategy for I-doped BiOCOOH nanoplates with enhanced visible light photocatalytic NOx removal

A simple ion-exchange method was developed for I-doped BiOCOOH nanoplates from the replacement of COOH− ions with I− ions in the interlayers of BiOCOOH. The as-prepared catalysts were characterized by XRD, SEM, TEM, XPS, UV-vis DRS PL and photocurrent generation. The photocatalytic activity of the as-prepared catalysts was evaluated by removal of NO in air at ppb level under visible light irradiation. As expected, the I-doped BiOCOOH (IHB-X, the X represents the molar ratio of KI to BiOCOOH) displayed increased visible light absorption and enhanced charge separation due to I-doping. At a saturate I-doping content, the IHB-1.00 catalyst with optimized electronic structure demonstrated the highest NO removal of 49.7% and excellent photochemical stability. This present work has demonstrated a new strategy for modification of layered photocatalyst via ion exchange.

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.

Fabrication of porous nanoflake BiMO x (M = W, V, and Mo) photoanodes via hydrothermal anion exchange

Most Bi-based photoelectrodes have suitable band gaps and can effectively promote the water oxidation reaction. However, simple preparation methods for Bi-based binary metal oxides as photoanodes are scarce. This paper describes a simple hydrothermal anion exchange method to synthesize Bi-based binary metal oxides with controlled morphologies. This synthesis process uses BiOI as the template and Bi source, which is eventually converted to Bi-based porous nanoflake photoanodes upon reaction with MO _x (M = W, V, and Mo)-containing precursors. The photoanodes show well-shaped porous nanoflake morphologies and exhibit impressive photoelectrochemical properties compared to Bi-based photoanodes synthesized by conventional methods. These three samples possess long-term stability under solar irradiation and show considerable photocurrent for sulfite oxidation.

Hollow porous carbon nitride immobilized on carbonized nanofibers for highly efficient visible light photocatalytic removal of NO

With the deterioration of air quality, great efforts were devoted to designing various photocatalysts for effective removal of NOx in air. However, the present photocatalysts have a fatal problem of low photocatalytic efficiency. In this work, a hollow porous carbon nitride nanosphere coupled with reduced graphene oxide (HCNS/rGO) was exploited as a visible-light photocatalyst to remove nitrogen monoxide in air at a low concentration (600 ppb level) under irradiation of an energy saving lamp. HCNS/rGO showed a NO removal ratio of 64%, which was superior to that of most other visible-light photocatalysts. The excellent photocatalytic ability of HCNS/rGO originates from the hollow porous morphology of HCNS and the grafted rGO on the surface. HCNS/rGO was immobilized on porous carbonized polymer nanofibers to obtain a photocatalytic membrane without affecting photocatalytic efficiency. Furthermore, the membrane showed excellent photochemical stability and recyclability.

Sulfur-doping synchronously ameliorating band energy structure and charge separation achieving decent visible-light photocatalysis of Bi2O2CO3

Sulfur doping simultaneously endows the wide-band-gap Bi₂O₂CO₃ promoted band energy structure and charge separation achieving enhanced visible-light photocatalytic performance for dye degradation and NO removal.

Interlayer-I-doped BiOIO3 nanoplates with an optimized electronic structure for efficient visible light photocatalysis

I-intercalated BiOIO₃ demonstrated outstanding NO removal ability due to its extended light response, enhanced oxidation capability and improved carrier separation endowed by the interbedded I atoms.

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.

Iodide surface decoration: a facile and efficacious approach to modulating the band energy level of semiconductors for high-performance visible-light photocatalysis

Iodide surface decoration enables the wide-band-gap Bi₂O₂CO₃ to possess a continuously tunable band gap and profoundly boosted visible-light photocatalytic performance for dye degradation and NO removal.

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.

Large-scale synthesis of self-assembled ultralong cannonite nanobelt film as a visible-light photocatalyst

Self-assembled macroscopic cannonite nanobelts could be transferred on substrates as thin films in a large scale and exhibit high visible-light photocatalytic activity, which would be a promising candidate for high-efficiency photocatalysts.

Novel BiIO4/BiVO4 composite photocatalyst with highly improved visible-light-induced photocatalytic performance for rhodamine B degradation and photocurrent generation

Novel BiIO₄/BiVO₄ heterojunction was successfully constructed for the first time. It exhibits significantly enhanced photocatalytic activity for degradation of RhB and photocurrent generation.