Bi2O3 Catalysts Research Articles

CFs-supported La-BiOIO3/Bi2O3 heterostructures via in situ growth strategies for efficiently removing diclofenac: Fermi level modulation, intermediates identification and radical mechanism

The charge transfer efficiency and the recyclability were still the potential factors limiting the widespread application of photocatalysts for pollutant removal. Herein, a novel design perspective for BiOIO3-based S-scheme heterojunction (La-BiOIO3/Bi2O3) with modulated Fermi level and enhanced internal electric field was proposed by in situ liquid-phase growth strategy. Meanwhile, the CFs@La-BiOIO3/Bi2O3 catalysts with high stability and easy recyclability were assembled based on industrial carbon fiber cloths, which can achieve efficiently photocatalytic removal of diclofenac (DCF, 95.5 %, 20 min) and bisphenol A (BPA, 100 %, 30 min) under simulated sunlight irradiation. The photocatalytic degradation rates of DCF were 52.8 and 12.4 times that of pure BiOIO3 and Bi2O3, respectively. The high specific surface area (39.74 m2·g−1) and suitable bandgap structure (2.74 eV) also demonstrated the excellence of the CFs@La-BiOIO3/Bi2O3 degradation system. Verification of heteroatom-driven electron rearrangement and charge migration route in heterostructure was performed through XPS analysis and Mott-Schottky experiments. Gaussian calculations, LC-MS, and toxicity assessments demonstrated that reactive oxygen species (ROS) such as ·O2− and ·OH selectively attacked the electronic groups of DCF and its intermediates, which combined with holes (h+) retained in the valence bands of Bi2O3 to synergistically achieve efficient degradation and detoxification of DCF. Finally, the charge migration mechanism for the photocatalytic elimination of DCF over CFs@La-BiOIO3/Bi2O3 photocatalyst was proposed. Similar studies can be extended to other structures capable of achieving rational Fermi level modulation and synchronous carrier introduction for the remediation of polluted waters, providing novel perspectives for improving photocatalytic driving capacity.

Electrochemical CO2 Reduction in the Presence of Flue Gas Impurities: Effect of NOx, SOx and O2

Electrochemically converting CO2 to valuable chemical products using renewable energy sources may present solutions to alter current increasing CO2 emission trends. Currently, electrolyzer research is almost exclusively done with pure CO2 streams that - in practice - would originate from carbon capture units that prevent CO2 release to the atmosphere [1]. The capture and purification steps are cost intensive processes which is why direct usage of flue gases that contain impurities is a highly interesting approach. For this reason, the performance of CO2 electrolyzers equipped with state-of-the-art Bi2O3 or Ag catalysts is investigated in this work with an impure CO2 feed stream containing SO2, NO or O2. The short-term effect of highly concentrated SO2 (10 000 ppm) and NO (8 300 ppm) impurities during CO2 electrolysis was previously described [2,3]. Our work [4] elaborates further on this matter through 20 h experiments with flue gas-like concentrations of 200 ppm SO2 or NO. The results show a stable operation without severe FE losses (remains >90%) and structural adaptations to neither Ag nor Bi2O3 by these impurities. The presence of oxygen in flue gas streams at concentrations of several percent is common and causes a major decrease in FE to the target products (CO or HCOO-) during electrolysis. This is a result of the competition between the ORR and CO2RR with the former occurring more preferentially. To overcome this, we have discovered two possible strategies, which allow high FE’s to CO2RR products even in the presence of oxygen. (1) By operating the electrolyzer at a sufficiently high overall current density, all of the O2 entering and reaching the electrode surface gets reduced, allowing the CO2RR to become the dominant reaction. Although this approach has a higher electricity penalty, the extra cost is negligible compared to the cost otherwise associated with the CO2 purification for CO2 streams with an O2 content below 3%. (2) Given that the ORR is mostly occurring at the carbon-based gas diffusion layers another approach to improve CO2RR efficiency in the presence of oxygen is to replace this conventional support with ultra hydrophobic PTFE membrane filters. Since they are inefficient oxygen reduction catalysts, CO2RR again takes up the major fraction of the applied current density. A downside of using PTFE is that an additional conductive layer is required in case the catalyst itself (e.g. for bismuth oxide) is not conductive enough. These results thus not only offer new insights into the impact of gaseous impurities during CO2 electrolysis, but also suggest a strategy to improve electrolyzer performance with O2-containing feed streams. Bibliography [1] Lee M.Y., Environ. Sci. and Technol.; DOI: 10.1080/10643389.2019.1631991[2] Luc W.; JACS, DOI: 10.1021/jacs.9b03215[3] Ko B., Nature Comm. DOI : 10.1038/s41467-020-19731-8[4] Van Daele S ., J. Appl. Catal. B, Environ.; DOI: 10.1016/J.APCATB.2023.123345 Figure 1

Non-thermal atmospheric-pressure positive pulsating corona discharge in degradation of textile dye Reactive Blue 19 enhanced by Bi2O3 catalyst

In this work, monoclinic Bi2O3 was applied for the first time, to the best of our knowledge, as a catalyst in the process of dye degradation by a non-thermal atmospheric-pressure positive pulsating corona discharge. The research focused on the interaction of the plasma-generated species and the catalyst, as well as the role of the catalyst in the degradation process. Plasma decomposition of the anthraquinone reactive dye Reactive Blue 19 (RB 19) was performed in a self-made reactor system. Bi2O3 was prepared by electrodeposition followed by thermal treatment, and characterized by x-ray diffraction, scanning electron microscopy and energy-dispersive x-ray techniques. It was observed that the catalyst promoted decomposition of plasma-generated H2O2 into •OH radicals, the principal dye-degrading reagent, which further attacked the dye molecules. The catalyst improved the decolorization rate by 2.5 times, the energy yield by 93.4% and total organic carbon removal by 7.1%. Excitation of the catalyst mostly occurred through strikes by plasma-generated reactive ions and radical species from the air, accelerated by the electric field, as well as by fast electrons with an energy of up to 15 eV generated by the streamers reaching the liquid surface. These strikes transferred the energy to the catalyst and created the electrons and holes, which further reacted with H2O2 and water, producing •OH radicals. This was indentified as the primary role of the catalyst in this process. Decolorization reactions followed pseudo first-order kinetics. Production of H2O2 and the dye degradation rate increased with increase in the input voltage. The optimal catalyst dose was 500 mg∙dm−3. The decolorization rate was a little lower in river water compared with that in deionized water due to the side reactions of •OH radicals with organic matter and inorganic ions dissolved in the river water.

Spherical Bi2O3/ATO catalyst with N2 pre-reduction electrocatalytic reduction of CO2 to formic acid

Bi2O3 catalyst with Bi-O bond crystal structure has more active sites, which shows better CO2 catalytic performance than pure Bi catalysts in many catalytic reactions. How to strengthen the Bi-O bond in Bi2O3 to obtain higher selectivity and catalytic activity is a problem worthy of consideration. Here, we develop a N2 pre-reduced spherical Bi2O3/ATO catalyst that has a high formate Faradaic efficiency of 92.7%, which is superior to the existing tin oxide catalyst. Detailed electrocatalytic analysis shows that N2 pre-reduction and spherical structure are helpful for Sn to stabilize the oxidation state of Bi, thus retaining part of the Bi-O structure. The existence of the Bi-O structure can reduce the energy barrier of the CO2 production *OCHO reaction and promote the reaction rate of the CO2-*OCHO-HCOOH path, thus promoting the formation of formate.

ZnO-Bi2O3 Heterostructured Composite for the Photocatalytic Degradation of Orange 16 Reactive Dye: Synergistic Effect of UV Irradiation and Hydrogen Peroxide

The development of semiconductor photocatalysts has recently witnessed notable momentum in the photocatalytic degradation of organic pollutants. ZnO is one of the most widely used photocatalysts; however, its activity is limited by the inefficient absorption of visible light and the fast electron–hole recombination. The incorporation of another metal or semiconductor with ZnO boosts its performance. In this present study, a heterostructured ZnO-Bi2O3 composite was synthesized via a simple co-precipitation method and was investigated for the UV-driven photocatalytic degradation of the Reactive Orange 16 (RO16), a model textile dye. The successful fabrication of ZnO-Bi2O3 microstructures with crystalline nature was characterized using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and energy-dispersive X-ray (EDX). The discoloration of the dye solution was quantified using UV–Vis spectroscopy to determine the photocatalytic efficiency. The photocatalytic activity results demonstrated that the photodegradation at ZnO-Bi2O3 heterojunction was more efficient and 300 and 33% faster than individual Bi2O3 and ZnO catalysts, respectively, an effect that is indicative of a synergistic effect. In the presence of ZnO-Bi2O3 particles, the UV light-driven activity for RO16 degradation was twice as high as in its absence. The influence of adding the oxidant H2O2 on the UV-induced photocatalytic degradation was investigated and the results revealed a two-time increase in the photocatalytic activity of ZnO-Bi2O3 compared to UV irradiation alone, which could be ascribed to a summative degradative effect between UV and H2O2. Hence, this approach holds the potential for environmentally friendly wastewater treatment.

Surface Dual Metal Occupations in Fe-Doped FexBi2-xO3 Induce Highly Efficient Photocatalytic CO2 Reduction.

CO2 possesses extraordinary thermodynamic stability, and its reduction reaction involves multiple electron-transfer processes. Thus, high-density electron occupation on a catalyst surface is an effective driving force for improving the photocatalytic activity. Here, we report on the fabrication of Fe-doped Bi2O3 catalysts (denoted as FexBi2-xO3) with different Fe contents using the solvothermal method. The self-assembled catalyst has a nanoflower-like morphology, and its performance of CO2 reduction to CO is improved largely dependent on the Fe content. In the sample with a 7.0% Fe content (Fe0.07Bi1.93O3), the CO evolution rate reaches 30.06 μmol g-1 h-1, which is about 6 times higher than the 4.95 μmol g-1 h-1 of pristine Bi2O3, and shows excellent photostability after three cycles, with each cycle lasting for 7 h. Theoretical calculation and spectral characterization reveal that such a good CO2 reduction reaction performance arises from effective surface occupation of Fe, which not only enhances sunlight absorption but also significantly increases the surface electron density on the double metal active sites. This work provides a new strategy for improving the photocatalytic performance by surface metal doping in some metal oxide photocatalysts.

Photoanode synthesis of ammonia based on a light reflex strategy and NiCe-layered double hydroxide and oxygen-vacancy Bi2O3 catalysts

Photoelectrocatalysis or photoelectrochemistry (PEC) strategies to synthesize NH3 by nitrogen reduction reaction (NRR) have attracted considerable attention in recent years, but the PEC-NRR synthesis of NH3 on photoanodes (vs commonly used photocathodes) is still a rather new topic worthy of in-depth study. Herein, the high-performance PEC-NRR synthesis of NH3 is achieved on an oxygen-vacancy Bi2O3 and then NiCe-layered double hydroxide modified fluorine-doped tin oxide photoanode biased at 0.4 V vs KCl-saturated calomel electrode, and the utilization of light source is improved by an Ag-mirror-film based light reflex. Under optimal conditions, the yield of NH3 is 16.9 mmol h−1 m−2, and it is increased to an apparent value of 27.8 mmol h−1 m−2 after counting the NRRs on both the photoanode and the Pt counter electrode, revealing that the photoanode strategy is promising for the green and sustainable synthesis of NH3 under ambient conditions. The NH3-synthesis mechanism is discussed after various characterizations and theoretical calculations.

In-situ constructing Cu1Bi1 bimetallic catalyst to promote the electroreduction of CO2 to formate by synergistic electronic and geometric effects

Electrochemical CO2 reduction to formate is a potential approach to achieving global carbon neutrality. Here, Cu1Bi1 bimetallic catalyst was prepared by a co-precipitation method. It has a ginger like composite structure (CuO/CuBi2O4) and exhibited a high formate faradaic efficiency of 98.07% at –0.98 V and a large current density of –56.12 mA·cm−2 at –1.28 V, which is twice as high as Bi2O3 catalyst. Especially, high selectivity (FEHCOO– > 85%) is maintained over a wide potential window of 500 mV. In-situ Raman measurements and structure characterization revealed that the reduced Cu1Bi1 bimetallic catalyst possesses abundant Cu-Bi interfaces and residual Bi-O structures. The abundant Cu-Bi interface structures on the catalyst surface can provide abundant active sites for CO2RR, while the Bi-O structures may stabilize the CO2*– intermediate. The synergistic effect of abundant Cu-Bi interfaces and Bi-O species promotes the efficient synthesis of formate by following the OCHO* pathway.

MWCNT supported V2O5 quantum dot nanoparticles decorated Bi2O3 nanosheets hybrid system: Efficient visible light driven photocatalyst for degradation of ciprofloxacin

A novel composite of multiwall carbon nanotube (MWCNT) supported V2O5 quantum dots decorated Bi2O3 hybrid was prepared by the simple wet-impregnation method, and the photocatalytic performance of the prepared samples was investigated against the photodegradation of ciprofloxacin (CIP). Herein, different samples of pristine, V2O5/Bi2O3 and MWCNT@V2O5/Bi2O3 hybrid photocatalyst were prepared and systematically characterized by various physicochemical techniques. The characterization results demonstrated that the introduction of MWCNT can change the energy band gap of V2O5/Bi2O3, and the band energies vary with a constituent of MWCNT@V2O5/Bi2O3 catalyst, in which MWCNT@V2O5/Bi2O3-5 (0.05 g@0.50 g:0.50 g) has the optimal band gap energy of 2.46 eV. The photocatalytic test demonstrates that the MWCNT@V2O5/Bi2O3-5 hybrid composites exhibited enhanced photocatalytic activity in CIP degradation compared to that pure and other photocatalyst and its degradation efficiency did not decrease significantly even after five cyclic experiments. The enhanced photocatalytic activity was due to the formation of heterojunction among MWCNT, V2O5 and Bi2O3, which distinctly improved the separation efficiency of the photogenerated charge carrier, thus increasing the degradation performance. This work gives a new approach to designing an efficient photocatalyst for contaminants degradation.

Atenolol removal from aqueous solutions using Bi2O3/TiO2 under UV-C and visible light irradiations

ABSTRACT In this study, Bi2O3/TiO2 composite was successfully synthesised using the solvothermal method, and the morphology, composition, and surface area of the composite were determined. Comparisons of photocatalytic performance were performed using Bi2O3/TiO2 for the decomposition of Atenolol (ATN) a β-blockers that is generally used to treat disorders such as hypertension and arrhythmias, as a model contaminant under visible light irradiation. The effects of different parameters such as solution pH, catalyst dosage, initial ATN concentration, reaction time, coexisting cations and anions, and turbidity on the degradation efficiency of ATN were investigated. An excellent synergistic effect was observed in the decomposition of ATN with the simultaneous application of Bi2O3/TiO2 and LED compared to single processes (synergistic index value, 4.027). The Bi2O3 catalyst has a much lower photocatalytic performance for the decomposition of ATN than the synthesised Bi2O3/TiO2 composite. The optimal rate for pH, catalyst dosage, and initial concentration of ATN was 7, 400 mg/l and 10 mg/l, respectively. Under optimal conditions, about 68.92% and 22.58% of ATN were degraded after 60 minutes in the presence of Bi2O3/TiO2 and Bi2O3 catalysts, respectively. However, these efficiencies are reduced to 51.83% and 12.4%, respectively, under 50 NTU. The addition of co-existing anions, especially PO4 3 ⁻, remarkably reduced the efficiency of ATN removal in the Bi2O3/TiO2/LED process. The presence of cations promoted the degradation of ATN in the Bi2O3/LED process, while the efficiency of ATN degradation was inhibited by the presence of cations in the Bi2O3/TiO2/LED process. The ATN removal efficiency using LED irradiation (49.02%) was much higher than that of UV-C irradiation (27.16%) when the concentration of ATN was 30 mg/L.

Mn-Doped Bi2O3 Nanosheets from a Deep Eutectic Solvent toward Enhanced Electrocatalytic N2 Reduction

The electrochemical nitrogen reduction reaction (NRR) is a promising green substitute to the resource-consuming Haber–Bosch process. However, it is still far from the industrialized application due to the deficiency of superior catalysts to activate the inert N2 molecules. Bi-based materials, especially Bi2O3, have been utilized for the NRR due to intrinsic suppression of the hydrogen evolution reaction (HER), but the inferior conductivity and low faradaic efficiency (FE) hamper its popularity in the NRR. Herein, for the first time, we designed Mn-doped Bi2O3 nanosheets from a deep eutectic solvent (DES) for the electrochemical NRR. The Mn-doped Bi2O3 nanosheets demonstrated a high NH3 yield rate of 23.54 μg h–1 mgcat.–1 with an enhanced FE of 21.63% in a Na2SO4 electrolyte at −0.1 V versus the reversible hydrogen electrode, superior to previous Bi2O3 catalysts. The result indicated that introducing Mn into Bi2O3 elevates the FE for the NRR by suppressing the adverse HER. Our work offers an instructive Mn doping strategy via the DES approach for ameliorating the NRR performance of Bi2O3, holding great promise for the design of advanced catalysts toward the NRR.

Transition metal incorporated, modified bismuth oxide (Bi2O3) nano photo catalyst for deterioration of rosaniline hydrochloride dye as resource for environmental rehabilitation

The work presented here deals with the fabrication of bare Bi2O3 and modified Bi2O3 photocatalyst. The Bi2O3 material was modified with selected transition metals Co2+, Ni2+ with the 1% and 3% atomic weight percent insitu doping method via co-precipitation strategy. These three catalysts were successfully utilized for the waste water purification via photocatalytic degradation route. These all fabricated materials were precisely characterized by characterization techniques such as XRD, SEM, TEM, BET, IR and UV-DRS. The characterization techniques reveal the successful synthesis of material and effective modification of bismuth oxide lattice. Since, surface area for modified Bi2O3 was found to be enhanced in comparison to the bare Bi2O3, as well as declined band gap energy for modified Bi2O3 clearly indicates the successful doping of Co2+, Ni2+ metals. The bare Bi2O3 and modified Bi2O3 catalyst were employed for photocatalytic degradation of cationic dye R-HCl dye. The modified Bi2O3 found to be excellent over degradation efficiency of R-HCl with almost 97% of dye degradation in comparison to the bare Bi2O3. Reactive oxygen species experiment demonstrate that the addition of isopropyl alcohol (IPA), benzoquinone (BQ) and EDTA found to be successful to quench .OH, O2.- and h+ in photocatalysis mechanism. Additionally, the modified Bi2O3 was employed for phenol molecule degradation to investigate the possible excitation of this molecule under visible light irradiation.

Bismuth Oxide Decorated Silicon Photocathodes for CO2 to Formate Solar Driven Conversion

In the field of CO2 electrochemical conversion, [1] the use of semiconducting photocathodes instead of non-photoactive traditionally used electrodes (e.g., metals and carbon) could provide a real benefit in terms of energy gain because it allows the electrochemical process to be activated by photogenerated electrons. [2] In that context, silicon appears as one of the most promising semiconducting materials owing to its small bandgap (1.1 eV) able not only to harvest photons from a large portion of the solar spectrum but also to encompass the different proton-assisted multielectron reduction potentials for CO2. [3],[4],[5] Herein, we report that silicon photocathodes modified with electrodeposited Bi nanostructures are highly active for the photoelectrocatalytic conversion of CO2 to formate in aqueous electrolytic medium. p-type Si photocathodes functionalized with Bi2O3 catalyst were easily fabricated without an additive polymer layer using a one-step and fast electrodeposition method. Both composition and morphology of the deposited Bi cocatalyst could be tuned by controlling the electrodeposition time. The photocathode prepared from a 5 s electrodeposition exhibited the highest photocurrent density (-24.1 mA cm-2) with partial formate photocurrent density j formate = -17.4 mA cm-2 at -1.03 V vs Reversible Hydrogen Electrode (corresponding to a 0.84 V overpotential for CO2 to formate conversion).Such values highlight the excellent catalytic activity for CO2 electroreduction of our photocathodes, [6] outperforming that of recently reported Bi-based catalysts deposited on Si. [7] Moreover, under our conditions, the formate production rate reached 14.9 mg h-1 cm-2 with a Faradaic efficiency for formate of 72%. We anticipate that the conversion efficiency of CO2 could be further improved by using structured silicon surfaces, as recently demonstrated by ourselves for sunlight-driven water splitting, [8] and/or Bi nanostructures. [1] a) J. Qiao, Y. Liu, F. Hong, J. A. Zhang, J. Chem. Soc. Rev. 2014, 43, 631-675. b) C. Costentin, M. Robert, J. M. Saveant, Chem. Soc. Rev. 2013, 42, 2423−2436. [2] a) J. L. White, M. F. Baruch, J. E. Pander III, Y. Hu, I. C. Fortmeyer, J. E. Park, T. Zhang, K. Liao, J. Gu, Y. Yan, T. W. Shaw, E. Abelev, A. B. Bocarsly, Chem. Rev. 2015, 115, 12888–12935. b) K. Maeda, Adv. Mater. 2019, 31, 1808205. [3] K. Sun, S. Shen, Y. Liang, P. E. Burrows, S. S. Mao, D. Wang, Chem. Rev. 2014, 114, 8662−8719. [4] a) D. He, T. Jin, W. Li, S. Pantovich, D. W. Wang, G. H. Li, Chem. Eur. J. 2016, 22, 13064. b) B. Kumar, J. M. Smieja, C. P. Kubiak, J. Phys. Chem. C 2010, 114, 14220. c) B. Kumar, M. Llorente, J. Froehlich, T. Dang, A. Sathrum, C. P. Kubiak, Annu. Rev. Phys. Chem. 2012, 63, 541. [5] E. Torralba-Penalver, Y. Luo, J.-D. Compain, S. Chardon-Noblat, B. Fabre, ACS Catal. 2015, 5, 6138. [6] D. Fu, J. Tourneur, B. Fabre, G. Loget, Y. Lou, F. Geneste, S. Ababou-Girard, C. Mériadec, ChemCatChem. 2020, 12, 5819. [7] a) Q. Gong, P. Ding, M. Xu, X. Zhu, M. Wang, J. Deng, Q. Ma, N. Han, Y. Zhu, J. Lu, Z. Feng, Y. Li, W. Zhou, Y. Li, Nat. Commun. 2019, 10:2807. b) P. Ding, Y. Hu, J. Deng, J. Chen, C. Zha, H. Yang, N. Han, Q. Gong, L. Li, T. Wang, X. Zhao, Y. Li, Mater. Today Chem. 2019, 11, 80-85. [8] a) J. Tourneur, B. Fabre, G. Loget, et al. J. Am. Chem. Soc. 2019, 141, 11954. b) K. Oh, V. Dorcet, B. Fabre, G. Loget, Adv. Energy Mater. 2019, 1902963. Figure 1

Boosting CO2 Capture and Its Photochemical Conversion on Bismuth Surface

The activity and efficiency of photocatalytic CO2 conversion are limited by a narrow spectral response range and fast electron–hole pair recombination. As plasmonic photocatalysts have become novel catalytic materials for visible light, herein, a typical Bi2O3 photocatalyst as a template to achieve simultaneous in situ bismuth reduction and coupling on the material surface via hydrogen–argon plasma alteration is used. Combining the surface plasmon resonance effect of Bi nanoparticles and the characteristics of composite photocatalytic materials, Bi–Bi2O3 exhibits excellent efficiency in light absorption and separation of photogenerated carriers; photocatalytic activity is significantly enhanced. The CO yields are changed with plasma‐treated duration; the maximum is reached at a treatment time of 3 min, where the rate of CO production is 29.87 μmol h−1 g−1 and CH4 production rate increases from 0 to 6.29 μmol h−1 g−1. The reaction mechanism is further confirmed by in situ Fourier‐transform infrared spectroscopy. Both the efficient light‐generated carrier separation and intense light absorption contribute to the high activity of the well‐designed Bi–Bi2O3 catalyst.

Dependence of the intrinsic phase structure of Bi2O3 catalysts on photocatalytic CO2 reduction

The combination of time-resolved transient photoluminescence with in-situ Fourier transform infrared spectroscopy has been conducted to investigate the intrinsic phase structure-dependent activity of Bi2O3 catalyst for CO2 reduction.

Large-scale synthesis of porous Bi2O3 with oxygen vacancies for efficient photodegradation of methylene blue

Photocatalytic degradation of organic pollutants has become a hot research topic because of its low energy consumption and environmental-friendly characteristics. Bismuth oxide (Bi2O3) nanocrystals with a bandgap ranging from 2.0 eV to 2.8 eV have attracted increasing attention due to high activity of photodegradation of organic pollutants by utilizing visible light. Though several methods have been developed to prepare Bi2O3-based semiconductor materials over recent years, it is still difficult to prepare highly active Bi2O3 catalysts in large scale with a simple method. Therefore, developing simple and feasible methods for the preparation of Bi2O3 nanocrystals in large scale is important for the potential applications in industrial wastewater treatment. In this work, we successfully prepared porous Bi2O3 in large scale via etching commercial BiSn powders, followed by thermal treatment with air. The acquired porous Bi2O3 exhibited excellent activity and stability in photocatalytic degradation of methylene blue. Further investigation of the mechanism witnessed that the suitable band structure of porous Bi2O3 allowed the generation of reactive oxygen species, such as O2−· and ·OH, which effectively degraded MB.

Nanostructured β‐Bi2O3 Fractals on Carbon Fibers for Highly Selective CO2 Electroreduction to Formate

Abstract3D Bi2O3 fractal nanostructures (f‐Bi2O3) are directly self‐assembled on carbon fiber papers (CFP) using a scalable hot‐aerosol synthesis strategy. This approach provides high versatility in modulating the physiochemical properties of the Bi2O3 catalyst by a tailorable control of its crystalline size, loading, electron density as well as providing exposed stacking of the nanomaterials on the porous CFP substrate. As a result, when tested for electrochemical CO2 reduction reactions (CO2RR), these f‐Bi2O3 electrodes demonstrate superior conversion of CO2 to formate (HCOO−) with low onset overpotential and a high mass‐specific formate partial current density of −52.2 mA mg−1, which is ≈3 times higher than that of the drop‐casted control Bi2O3 catalyst (−15.5 mA mg−1), and a high Faradaic efficiency (FEHCOO−) of 87% at an applied potential of −1.2 V versus reversible hydrogen electrode. The findings reveal that the high exposure of roughened β‐phase Bi2O3/Bi edges and the improved electron density of these fractal structures are key contributors in attainment of high CO2RR activity.

Significantly improved and synergistic effect of Pt–ZnO–Bi2O3 ternary hetero-junctions toward anode-catalytic oxidation of methanol in alkali

Pt-nanoparticle decorated nano-sized ZnO–Bi2O3 hetero-junctions of various compositions are synthesized along with binary Pt–ZnO and Pt–Bi2O3, characterized and used as anode-catalysts for methanol oxidation reaction in alkali. The peak current density of most of the Pt–ZnO–Bi2O3 catalysts in cyclic voltammetry is higher than these of Pt– Bi2O3 and Pt– ZnO indicating beneficiary and synergistic effect of the ternary composites. The best Pt–ZnO–Bi2O3 electrode containing ZnO:Bi2O3 = 5:1, exhibits significantly high current density, 932.1 mA mg−1 Pt which is 9.7, 5.5 and 12.1 times higher than that of Pt–Bi2O3 (95.4), Pt–ZnO (167.8) and synthesized Pt (76.5) catalysts. The mass normalized equilibrium exchange current density (4.46 × 10−4 mA mg−1 Pt) towards methanol oxidation reaction on the best electrode is approximately 3.6 × 104 and 9.5 times higher than these on Pt–Bi2O3 and Pt–ZnO electrodes. The chronoamperometry conforms to the results of CV study. The charge transfer resistance of the catalyst obtained from Nyquist plot is 12.6 and 8.2 times less than these offered by Pt–Bi2O3 and Pt–ZnO catalysts. Multi-scan CV experiments with the best ternary composite shows excellent stability in catalytic activity towards methanol oxidation reaction. The HPLC study helps understanding the selectivity of the catalysts among various products, which facilitates prediction of mechanistic pathways.

Nano Structured Bi2O3 Catalyzed Synthesis of 3-Phenyl-[1,2,4]Triazolo[3,4-a]Phthalazines and Their Cross-coupling Reaction Under Aqueous Conditions

A novel and an expeditious approach for the synthesis of 3-phenyl-[1,2,4]triazolo[3,4-a]phthalazine derivatives has been achieved from 1,4-dichlorophthlazine and benzohydrazides in the presence of nano Bi2O3 catalyst. 3-Phenyl-[1,2,4]triazolo[3,4-a]phthalazines undergo substitution reaction with various –OH group to produce 6-substituted-3-phenyl-[1,2,4]triazolo[3,4-a]phthalazines in excellent yields under aqueous condition in the presence of Pd(OAc)2, BINAP and nano Bi2O3 catalyst. The present protocol tolerates various functional groups and represents a reliable and time efficient method.

Visible-Light-Driven MADIX Polymerisation via a Reusable, Low-Cost, and Non-Toxic Bismuth Oxide Photocatalyst.

The continuous amalgamation of photocatalysis into existing reversible deactivation radical polymerisation (RDRP) processes has initiated a rapidly propagating area of polymer research in recent years. We introduce bismuth oxide (Bi2 O3 ) as a heterogeneous photocatalyst for polymerisations, operating at room temperature with visible light. We demonstrate formidable control over degenerative chain-transfer polymerisations, such as macromolecular design by interchange of xanthate (MADIX) and reversible addition-fragmentation chain-transfer (RAFT) polymerisation. We achieved narrow molecular weight distributions and attribute the excellent temporal control of a photo-induced electron transfer (PET) process. This methodology was employed to synthesise diblock copolymers combining differently activated monomers. The Bi2 O3 catalyst system has the additional benefits of low toxicity, reusability, low-cost, and ease of removal from the reaction mixture.