Search query: Bi2WO6, active site

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abstract: At present, environmental pollution caused by refractory organic pollutants becomes more serious. Semiconductor based photocatalysis technology, an idea and continuable technology by solar light driven, is widely employed to address this situation. Here, oxygen vacancy rich WO3 decorated monolayer Bi2WO6 nanosheet composite as an atomic scale heterojunction with high active species and ultrafast charge carrier transfer was rationally constructed. The atomic scale Vo WO3/Bi2WO6 composite displayed remarkable photoactivity comparing with pristine Vo WO3 and Bi2WO6 ultrathin nanosheet, and about 79.5% of Ciprofloxacin can be degraded within 120 min under visible light irradiation when 40 mg of photocatalyst was added into CIP solution (10 mg/L) The promoted photoactivity can be ascribed to the following points: (1) the composite possesses enormous surface pit, thereby expanding the species surface area and exposing more active site to promote antibiotic absorption; (2) the presence of abundant oxygen vacancy can facilitate the formation of more electrons, which can be consumed by adsorbed molecular oxygen to produce superoxide radical, thereby accelerating degradation organic pollutant; (3) ultrathin Vo WO3 nanosheet decorated monolayer Bi2WO6 can shorten the charge carrier transfer distance and enlarge interface contact area, then ensuring remarkable photodegradation efficiency. The reasons for promoted photodegradation efficiency were elaborated based on experiments results and ESR analysis and the degradation pathways of CIP were recorded via (LC MS)/MS] After 5 run for the degradation of CIP, Vo WO3/Bi2WO6 composite also exhibited great photodegradation efficiency, thereby demonstrating its excellent stability and reusability.
author_names: Mingming Zhang

Cui Lai

Bisheng Li

Danlian Huang

Shiyu Liu

Lei Qin

Huan Yi

Yukui Fu

Fuhang Xu

Minfang Li

Ling Li
title: Ultrathin oxygen vacancy abundant WO3 decorated monolayer Bi2WO6 nanosheet: A 2D/2D heterojunction for the degradation of Ciprofloxacin under visible and NIR light irradiation.
venue: Journal of colloid and interface science
year: 2019

abstract: Abstract In this work, Bi2WO6 hollow microspheres containing oxygen vacancies (OVs BWO) was synthesized by a solvothermal template free method. Raman, EPR and XPS spectra provide sufficient evidence for the existence of OVs in the material. Its activity toward photocatalytic nitrogen fixation was evaluated. Experimental results showed that the OVs BWO with a BET surface area of 80.5 m2g 1 exhibited the ammonia yield of 106.4 mmol*gcat 1 under simulated sunlight for 2 h, which is ca. 18 times higher than that of equal area nest like Bi2WO6 without oxygen vacancies. The enhanced activity is mainly attributed to the metastable electrons within the sub band (i.e. defect energy level) induced by oxygen vacancies to p anti bonding orbitals of N2 with a manner of the non radiative transfer, leading to the activation of nitrogen molecules. The activation and hydrogeneration processes of nitrogen at active site of OVs BWO were studied by DFT calculation and the possible mechanisms were proposed. The sub band extends the light absorption region of OVs BWO to 700 nm. Transient photocurrent response showed that the sub band electron excitation accelerates the transfer of charges and hinders the electron hole recombination. It can be perfectly reused five times when air and nitrogen are used as nitrogen sources, thus the OVs BWO hollow microspheres offer a promising alternative for efficient N2 fixation under ambient conditions.
author_names: Tianyu Wang

Caiting Feng

Jiquan Liu

Huaiming Hu

Jun Hu

Ganglin Xue
title: Bi2WO6 hollow microspheres with high specific surface area and oxygen vacancies for efficient photocatalysis N2 fixation
year: 2021

abstract: The structure of the low temperature polar (orthorhombic) phase of russellite (Bi2WO6) was examined on artificial specimens with precise single crystal X ray diffraction experiments. The final atomic arrangement thus obtained was identical to that reported by Knight [Miner. Mag. (1992) 56, 399 409] with powder neutron diffraction. The residual density attributable to a stereochemically active lone pair of electrons of bismuth was prominent at approximately the centre of a larger cap of BiO8 square antiprisms, that is on the line from the Bi sites to an adjacent WO42 slab along the b axis direction. Quite uneven Bi O distances and the formation of a vacant coordination hemisphere (within 3 A) should, therefore, be ascribed to the strong demand of bismuth to form shorter Bi O bonds to use up its electrostatic charge within its coordination environment. The shift of bismuth along c propagates via the correlated shift of the W site and these cooperative shifts cause ferroelectricity in the compound. This propagation was easily effected by the intrusion of molecules such as acetone into the structure.
author_names: Hiroki Okudera

Yuka Sakai

Ken-ichi Yamagata

Hiroaki Takeda
title: Structure of russellite (Bi2WO6) origin of ferroelectricity and the effect of the stereoactive lone electron pair on the structure.
venue: Acta crystallographica Section B, Structural science, crystal engineering and materials
year: 2018

abstract: Development of sensor materials based on metal oxide semiconductors (MOS) for selective gas sensors is challenging for the tasks of air quality monitoring, early fire detection, gas leaks search, breath analysis, etc. An extensive range of sensor materials has been elaborated, but no consistent guidelines can be found for choosing a material composition targeting the selective detection of specific gases. Fundamental relations between material composition and sensing behavior have not been unambiguously established. In the present review, we summarize our recent works on the research of active sites and gas sensing behavior of n type semiconductor metal oxides with different composition (simple oxides ZnO, In2O3, SnO2, WO3; mixed metal oxides BaSnO3, Bi2WO6) and functionalized by catalytic noble metals (Ru, Pd, Au) The materials were variously characterized. The composition, metal oxygen bonding, microstructure, active sites, sensing behavior, and interaction routes with gases (CO, NH3, SO2, VOC, NO2) were examined. The key role of active sites in determining the selectivity of sensor materials is substantiated. It was shown that the metal oxygen bond energy of the MOS correlates with the surface acidity and the concentration of surface oxygen species and oxygen vacancies, which control the adsorption and redox conversion of analyte gas molecules. The effects of cations in mixed metal oxides on the sensitivity and selectivity of BaSnO3 and Bi2WO6 to SO2 and VOCs, respectively, are rationalized. The determining role of catalytic noble metals in oxidation of reducing analyte gases and the impact of acid sites of MOS to gas adsorption are demonstrated.
author_names: Artem Marikutsa

Marina N Rumyantseva

Elizaveta A Konstantinova

Alexander Gaskov
title: The Key Role of Active Sites in the Development of Selective Metal Oxide Sensor Materials
venue: Sensors
year: 2021

abstract: Molecular dynamical (MD) simulations were performed to study the structure sensitivity of H2O adsorption on adsorption different Bi2WO6 and grapheme supported Bi2WO6 surfaces. Results show that stronger interaction happens between H2O and Bi2WO6 (001) than the interactions (between H2O and Bi2WO6 (100) and between H2O and Bi2WO6 (010) and O atom of the surface acts as the active site for H2O adsorption. The adsorption modes and locations of H2O on G Bi2WO6 distinct with those on Bi2WO6 surfaces. The maximum adsorption amount of H2O on graphene is under 333K and 373K, with the value of 12.0403x10 5mol/m2 and 12.0538x10 5mol/m2. The maximum adsorption amount of H2O adsorption on Bi2WO6 (100) G Bi2WO6 (100) and G Bi2WO6 (001) is under 303K, 303K, and 333K, with 6.4079x10 5mol/m2, 9.1096x10 5mol/m2, and 11.1917x10 5mol/m2, respectively. Meanwhile, the maximum adsorption amount of H2O adsorption on G Bi2WO6 (010) is under 353K and 373K, with the value of 10.0452x10 5mol/m2 and 10.5417x10 5mol/m2. Results point out the optimal catalyst and the most appropriate pressure and temperature for H2O interacting to Bi2WO6 and grapheme supported Bi2WO6.
author_names: Xue Qing Hu

Chen Lin

Liang Tang

Xunyong Liu
title: Structure Sensitivity of H2O Adsorption on Graphene Supported Bi2WO6
year: 2013

abstract: Immobilization of reduced graphene oxide (RGO) Bi2WO6 is an ideal method for obtaining antifouling membranes for membrane distillation (MD) processes. Poly(vinylidene fluoride) membranes modified with RGO Bi2WO6 were successfully obtained with a double layer coating method through non solvent induced phase separation. The water contact angle was improved by about 30deg by RGO Bi2WO6; this indicated that the surface modification obviously increased the membrane hydrophobicity. The high desalination rate proved that all of the prepared membranes were appropriate for the MD process. The RGO Bi2WO6 modified membranes achieve 26.26 59.95% removal rates in 10 mg/L aqueous ciprofloxacin under visible light for 7.5 h. It was possible to erase strongly bound foulants and recover the prepared membrane's permeation flux by 3 h of visible light irradiation. The RGO Bi2WO6 modified membrane with a high hydrophobicity, fouling mitigation, and photocatalytic capability presents huge potential for the treatment of high salt antibiotic wastewater use in the MD process. (c) 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 45426.
author_names: Yukun Li

Liang Zhu
title: Evaluation of the antifouling and photocatalytic properties of novel poly(vinylidene fluoride) membranes with a reduced graphene oxide Bi2WO6 active layer
year: 2017

abstract: Electrochemical reduction of CO2 to chemical fuel offers a promising strategy for managing the global carbon balance, but presents challenges for chemistry due to the lack of effective electrocatalyst. Here we report atomically dispersed nickel on nitrogenated graphene as an efficient and durable electrocatalyst for CO2 reduction. Based on operando X ray absorption and photoelectron spectroscopy measurements, the monovalent Ni(i) atomic center with a d9 electronic configuration was identified as the catalytically active site. The single Ni atom catalyst exhibits high intrinsic CO2 reduction activity, reaching a specific current of 350 A gcatalyst 1 and turnover frequency of 14,800 h 1 at a mild overpotential of 0.61 V for CO conversion with 97% Faradaic efficiency. The catalyst maintained 98% of its initial activity after 100 h of continuous reaction at CO formation current densities as high as 22 mA cm 2.Electrocatalysts with improved activity and stability for the conversion of CO2 to CO are being sought. Using operando spectroscopies, the authors identify atomically dispersed Ni(i) as the active site in a nitrogenated graphene supported catalyst with high intrinsic activity and stability over 100 hours.
author_names: Hong Bin Yang

Sung-Fu Hung

Song Liu

Kaidi Yuan

Shu Sean Miao

Liping Zhang

Xiang Huang

Hsin-Yi Wang

Weizheng Cai

Rong Chen

Jiajian Gao

Xiaofeng Yang

Wei Chen

Yanqiang Huang

Hao Ming Chen

Chang Ming Li

Tao Zhang

Bin Liu
title: Atomically dispersed Ni(i) as the active site for electrochemical CO2 reduction
year: 2018

abstract: Abstract The release of organic contaminant such as dye has become a major environmental issue. Bismuth tungstate (Bi2WO6) is one of the perovskites based photocatalysts shows a great ability to photodegrade organic dye under solar light irradiation. In this study, Bi2WO6 with different physicochemical properties was synthesized using one pot solvothermal method by varying the reaction temperature ranging from 120 degC to 180 degC. The Bi2WO6 synthesized at 140 degC (BWO 140) exhibited the highest photocatalytic activity (8.0 x 10 3 min 1) toward Erichrome Black T (EBT) dye. The superiority of Bi2WO6 photodegradation was mainly attributed to a synergistic effects of large surface area, small crystallite size, low electron recombination, and the presence of oxygen vacancies. Moreover, it was interesting to note that the BWO 140 could be reused for six consecutive cycles, without any significant deterioration. It was demonstrated that, photogenerated hole (h+ was the most important active species of Bi2WO6 to initiate the photocatalytic reaction.
author_names: Magdeline Tze Leng Lai

Chin Wei Lai

Kian Mun Lee

Soon Wei Chook

Thomas Chung-Kuang Yang

Siewhui Chong

Joon Ching Juan
title: Facile one pot solvothermal method to synthesize solar active Bi2WO6 for photocatalytic degradation of organic dye
venue: Journal of Alloys and Compounds
year: 2019

abstract: The broad absorption range and high carrier separation efficiency of photocatalysts are important for improving photocatalytic performance. Herein, nitrogen doped graphene quantum dots (NGQDs) as effective active sites and collectors of charge carriers in modified Z scheme g C3N4/Bi2WO6 heterojunctions were obtained by a facile hydrothermal method, and dramatically enhanced the electron hole separation efficiency and light harvesting ability. NGQD modified Z scheme g C3N4/Bi2WO6 heterojunctions exhibited outstanding universal photocatalytic degradation activity for removing various antibiotics such as tetracycline (TC) ciprofloxacin (CIP) oxytetracyline (OTC) etc. under visible (vis) and near infrared (NIR) light irradiation owing to the charge carriers' collection effect and up conversion luminescence properties of NGQDs. In addition, the photocatalytic reaction mechanism was also revealed by active species trapping experiments and the electron spin resonance (ESR) technique, which indicated that the influencing order of active species on the photocatalytic reaction is .O2 h+ .OH.
author_names: Huinan Che

Chunbo Liu

Wei Hu

Hao Hu

Liu Jinqiao

Jianying Dou

Weidong Shi

Chunmei Li

Hongjun Dong
title: NGQD active sites as effective collectors of charge carriers for improving the photocatalytic performance of Z scheme g C3N4/Bi2WO6 heterojunctions
year: 2018

abstract: Oxygen vacancy on the surface of metal oxides is one of the most important defects which acts as the reactive site in a variety of catalytic reactions. In this work, operando spectroscopy methodology was employed to study the CO2 methanation reaction catalyzed by Ru/CeO2 (with oxygen vacancy in CeO2) and Ru/a Al2O3 (without oxygen vacancy) respectively, so as to give a thorough understanding on active site dependent reaction mechanism. In Ru/CeO2 catalyst, operando XANES, IR, and Raman were used to reveal the generation process of Ce(3+ surface hydroxyl, and oxygen vacancy as well as their structural evolvements under practical reaction conditions. The steady state isotope transient kinetic analysis (SSITKA) type in situ DRIFT infrared spectroscopy undoubtedly substantiates that CO2 methanation undergoes formate route over Ru/CeO2 catalyst, and the formate dissociation to methanol catalyzed by oxygen vacancy is the rate determining step. In contrast, CO2 methanation undergoes CO route over Ru surface in Ru/a Al2O3 with the absence of oxygen vacancy, demonstrating active site dependent catalytic mechanism toward CO2 methanation. In addition, the catalytic activity evaluation and the oscillating reaction over Ru/CeO2 catalyst further prove that the oxygen vacancy catalyzes the rate determining step with a much lower activation temperature compared with Ru surface in Ru/a Al2O3 (125 vs 250 degC)
author_names: Fei Wang

Shan He

Hao Chen

Bin Wang

Lirong Zheng

Min Wei

David G Evans

Xue Duan
title: Active Site Dependent Reaction Mechanism over Ru/CeO2 Catalyst toward CO2 Methanation.
venue: Journal of the American Chemical Society
year: 2016