RSC Advances
·
2019
·Vol. 9
·期 5
·2764-2771
·
IF 3.049
Fuhang Mai,Kai Cui,Zhe Wen,Kai Wu,Fei Yan,Mengmeng Chen,Hong Chen,Yongdan Li
The conversion of guaiacol is examined at 300 °C in supercritical ethanol over a H2WO4 catalyst. Guaiacol is consumed completely, meanwhile, 16.7% aromatic ethers and 80.0% alkylphenols are obtained. Interestingly, tert-butylphenols are produced mainly with a high selectivity of 71.8%, and the overall selectivity of 2,6-di-tert-butylphenol and 2,6-di-tert-butyl-4-ethylphenol is as high as 63.7%. The experimental results indicate that catechol and 2-ethoxyphenol are the intermediates. Meanwhile, the WO3 sites play an important role in the conversion of guaiacol and the Brønsted acid sites on H2WO4 enhance the conversion and favour a high selectivity of the tert-butylphenols. The recycling tests show that the carbon deposition on the catalyst surface, the dehydration and partial reduction of the catalyst itself are responsible for the decay of the H2WO4 catalyst. Finally, the possible reaction pathways proposed involve the transetherification process and the alkylation process during guaiacol conversion.
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APPLIED PHYSICS A-MATERIALS SCIENCE & PROCESSING
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2019
·Vol. 125
·期 2
·1-10
·
IF 1.784
Chai Chen,Liu Jianxin,Wang Yawen,Zhang Xiaochao,Duan Donghong,Fan Caimei,Wang Yunfang
A h-WO 3 decorated Ag–AgCl composite was prepared through facile precipitation and photoreduction methods and demonstrated to be a highly efficient and stable photocatalyst for the degradation of Rhodamine B (RhB) under visible light. Ag–AgCl/h-WO 3 exhibited much improved photocatalytic performance was elucidated from the physical–chemical properties of AgCl and h-WO 3 and the surface plasmon resonance effect of the Ag particles. The techniques of X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), X-ray photoelectron spectrometry (XPS) and photocurrent were used to characterize crystalline phases, morphology, composition and separation efficiency between electrons (e − ) and holes (h + ) of the synthesized composite photocatalyst. XPS results confirmed the existence of W 5+ and W 6+ on the surface of h-WO 3 sample, which favored electrons transfer between AgCl and Ag, and generated superoxide radical for the degradation of RhB. The active species trapping experiments results further demonstrated that the formation of superoxide radical during the system. Finally, the underlying photocatalytic mechanism for the removal of RhB by Ag–AgCl/h-WO 3 composite was examined.
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Science Bulletin
·
2019
·
IF 6.277
Nana Han,Kai Liu,Xinping Zhang,Meng Wang,Pan Du,Zhaohui Huang,Daojin Zhou,Qian Zhang,Tengfei Gao,Yin Jia,Liang Luo,Jianjun Wang,Xiaoming Sun
Solar-powered desalination is a promising way to resolve the worldwide water crisis for its low consumption and simple facility. Considering the fragility and aggregations of traditional materials, which may decrease efficiency, we herein introduce a robust tungsten carbide (WC) nanoarray film as a stable and efficient photothermal material, whose absorption is over 97.5% throughout almost the whole solar spectrum range (220–2200 nm) due to nanoarray structure and thus enhanced localized surface plasmon resonance. Besides, for the first time, we modified the film with sandwich wettability . It accelerates evaporation by reducing water’s reflection of light, enlarging hydrophobic-hydrophilic boundaries, and depressing heat dissipation. Combining high absorption with unique wettability, the WC nanoarray film offers high solar-to-vapor efficiency of 90.8% and produces drinking water at the rate of (1.06 ± 0.10) kg m −2 h −1 from man-made seawater and (0.98 ± 0.18) kg m −2 h −1 from heavy metal sewage under one sun (AM 1.5) while 98% performance remains after 1 h × 100 times’ reutilization.
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JOURNAL OF SOLID STATE ELECTROCHEMISTRY
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2019
·Vol. 23
·期 5
·1621-1630
·
IF 2.531
Zhao Liu-Dan,Zhang Qian,Fan Jin-Bin,Yin Li-Qiang,Qi Peng-Wei,Yao Hong-Chang,Li Zhong-Jun
The search for efficient and powerful photoanode materials remains one of the toughest challenges in photoelectrochemical (PEC) water splitting because the oxygen evolution reaction on the photoanode is a rate-limiting process. On the other hand, the semiconductor/liquid interface is a key factor governing the water splitting efficiency due to its influence on charge separation and collection. Herein, we synthesized vertically aligned WO 3 nanosheet array (NS) films on fluorine-doped tin oxide (FTO), and followed by electroreduction for tuning the surface structure of WO 3 NSs. A disordered layer is formed on the surface of WO 3 NSs by controlling the external bias voltage and reduction time of electroreduction, and its thickness of the disordered layer varies with reduction time. The optimal WO 3 NSs with a 1.2 nm disorder layer thickness exhibit a remarkable photocurrent density of 1.07 mA cm −2 at 1.23 V vs reversible hydrogen electrode (RHE) under AM 1.5G illumination, which is 1.43 times of pristine WO 3 NSs. The results indicate that the electroreduction voltage and reduction time exert great influence on the formation of the surface disordered layer, and the optimized reduction conditions can enhance charge transfer and charge separation efficiency, substantially improving the PEC performance of WO 3 photoanode.
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APPLIED CATALYSIS B-ENVIRONMENTAL
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2018
·
IF 11.698
Longbo Jiang,Xingzhong Yuan,Guangming Zeng,Jie Liang,Xiaohong Chen,Hanbo Yu,Hou Wang,Zhibin Wu,Jin Zhang,Ting Xiong
Artificial Z-scheme photocatalyst can not only reduce the recombination of photogeneraged electron–holepairs, but also retain prominent redox ability. In this study, direct solid-state dual Z-scheme WO 3 /g-C 3 N 4 /Bi 2 O 3 photocatalyst was successfully synthesized by one step co-calcination stratage using tungstic acid, melamine and bismuth (III) nitrate pentahydrate as the precursors. Surface, morphological, and structural properties of the resulting materials were comprehensive characterized by XRD, XPS, SEM, TEM, UV–vis diffuse reflection spectroscopy, BET surface areas, photoluminescence and ESR analysis. The WO 3 /g-C 3 N 4 /Bi 2 O 3 composite exhibited superior photocatalytic activities for tetracycline degradation than that of pure g-C 3 N 4 , WO 3 , Bi 2 O 3 and their binary composites under visible light irradiation. The enhanced photocatalytic performance of WO 3 /g-C 3 N 4 /Bi 2 O 3 composite can be ascribed to improved visible light absorption, increased surface area and enhanced separation efficiency of photo-generated electron-hole pairs. In addition, the photocatalyst exhibits high stability and reusability. On the basis of the results, a novel direct solid-state dual Z-scheme photocatalytic mechanism was also proposed.
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CHEMICAL ENGINEERING JOURNAL
·
2018
·
IF 6.735
Zhuocheng Yin,Yuyu Bu,Jun Ren,Shuai Chen,Daming Zhao,Yihui Zou,Shaohua Shen,Dongjiang Yang
Tungsten trioxide (WO 3 ) is believed to be a promising electrode candidate for supercapacitors, due to its reversible surface redox reaction resulted from the almost same W-O bond lengths with different oxidation states. However, the specific capacitance of WO 3 electrode is very low (<250 mF cm −2 ) because of its low conductivity and slow surface redox reaction kinetics. Herein, to address these issues, mesoporous WO 3 nanosheets with exposed (2 0 0) facets were anchored on activated carbon cloth (ACC) via a simple two-step process including heat treatment and alcohol-thermal process. The ACC was coated on WO 3 seeds and proceed a heat treatment at 500 °C and the time of alcohol-thermal process were 7 h, 8 h, and 9 h labeled as WO 3 @ACC- n ( n = 7, 8, 9). SEM and TEM images confirmed the WO 3 nanosheets were successful anchored on the ACC. The WO 3 @ACC-8 electrode showed the best specific areal capacitance which could reach as high as 659 mF cm −2 at a current density of 5 mA cm −2 and superior stability with almost no decrease in 10,000 cycles in the presence of Na 2 SO 4 as the neutral electrolyte. The capacitance is encouragingly much higher than the previously reported values in a three-electrode system in the neutral aqueous condition. DFT calculations reveal that, in comparison to the (0 0 2) and (0 2 0) facets, the exposed (2 0 0) facets of the mesoporous WO 3 nanosheets triggers the superior Na + adsorption, which accelerates the Na + -involved surface redox reaction for the boosted supercapacitor performance. A flexible asymmetric supercapacitor (FASC) was fabricated from the WO 3 @ACC electrode, which exhibits high energy density (0.5 mWh cm −3 ) and power density (62 mW cm −3 ) without any attenuation during ±180° wide-angle bending.
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JOURNAL OF MATERIALS SCIENCE
·
2018
·Vol. 54
·期 1
·286-301
·
IF 2.993
Fang Hongbiao,Cao Xin,Yu Jiajie,Lv Xiang,Yang Nan,Wang Tianhe,Jiang Wei
Tungsten oxide (WO 3 ) is a well-known photocatalyst, but its application is restricted due to its low conduction band and reduction power. In addition, WO 3 catalyst in powder forms has little application prospect because of difficulties in separation and regeneration. In this work, we prepared WO 3 /Ag/AgCl films on conventional glass that not only have much enhanced photocatalytic capability but also can be readily regenerated. The WO 3 film was prepared on glass substrate by calcination of spin-coated W precursor. Ag/AgCl particles were then deposited on WO 3 film by an impregnating–precipitation–photoreduction method. The photocatalytic efficiency of WO 3 /Ag/AgCl was evaluated by using methyl orange (MO) and Rhodamine B (RhB) as target pollutants. The highest photocatalytic performance was achieved with the 3-WO 3 /Ag/AgCl film, being 18 and 13 times higher than that of pure WO 3 film for degradation of MO and RhB, respectively. The degradation rate for both MO and RhB by 3-WO 3 /Ag/AgCl film catalyst decreased by less than 5% after five cycled tests. The photodegradation mechanism was discussed based on the electrochemical impedance spectroscopy Nyquist tests, photoelectrochemical analysis and reactive oxygen species scavenging experiments. A possible all-solid-state Z-scheme mechanism is proposed based on the photoelectron chemical tests and radical trapping experiments. This study provides a feasible technique to prepare a photocatalytic film with practicability and reproducibility.
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CERAMICS INTERNATIONAL
·
2018
·
IF 3.057
Yongji Yao,Liangmiao Zhang,Zhang Chen,Chuanxiang Cao,Yanfeng Gao,Hongjie Luo
A simple two-step route is developed to fabricate hexagonal Cs x WO 3 nanoparticles . The core of this route is the preparation of the precursor by drying the mixture of WO 3 sol and CsCl , which leads to a higher Cs/W (0.32) ratio at low temperature in a short time. During reaction, oleic acid, used as a solvent, can be adsorbed on the surface of Cs x WO 3 nanoparticles, which results in small particle size (20 nm × 10 nm) and mild agglomeration. In addition, oleic acid also plays a role as a reducing agent in forming Cs x WO 3 nanoparticles without any further post-treatment. Furthermore, the film prepared from as-synthesized Cs 0.32 WO 3 nanoparticles shows excellent NIR-shielding properties (approximately 99% of the near-infrared radiation is cut off over a wavelength range of 780–2600 nm and the visible-light transmittance at 465 nm is 78.9%) when covering on an ordinary sheet of glass. A model which simulates the real environment is applied to evaluate heat-shielding performance of the Cs 0.32 WO 3 film while comparing with that of ordinary glass and commercial ITO glass (10 Ω □ −1 ). Results revealed that the Cs 0.32 WO 3 film showed superior performance than others.
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COLLOIDS AND SURFACES A-PHYSICOCHEMICAL AND ENGINEERING ASPECTS
·
2018
·
IF 2.829
Lianwei Wang,Jianxin Liu,Yawen Wang,Xiaochao Zhang,Donghong Duan,Caimei Fan,Yunfang Wang
A metastable hexagonal WO 3 (h-WO 3 ) was prepared by a hydrothermal reduction method with glycerol and the Ag 3 PO 4 /h-WO 3 composites were synthesized via a precipitation method. Several techniques were employed to characterize the Ag 3 PO 4 /h-WO 3 composites. Compared to the Ag 3 PO 4 /WO 3 photocatalysts, the Ag 3 PO 4 /h-WO 3 photocatalysts exhibited an excellent visible light photocatalytic performance for efficient degradation of methyl orange (MO). The analysis results showed that the favorable photocatalytic performance of the Ag 3 PO 4 /h-WO 3 composites were mainly attributed to the h + and O 2 − generated during the recycles of W 6+ and W 5+ . Furthermore, under the same conditions, the Ag 3 PO 4 /h-WO 3 composites showed better stability than pure Ag 3 PO 4 photocatalyst for degradation of MO, indicating that h-WO 3 played an important role in the process of degradation. Based on the results of trapping experiments and XPS characterization analysis, the photocatalytic mechanism of the Ag 3 PO 4 /h-WO 3 composites were proposed.
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ELECTROCHIMICA ACTA
·
2018
·
IF 5.116
Minji Yang,Huichao He,Hongping Zhang,Xiaohui Zhong,Faqin Dong,Gaili Ke,Yaqi Chen,Jinyan Du,Yong Zhou
High surface states induced photoelectrochemical (PEC) activity and stability issue is the major performance bottleneck for nanostructured WO 3 photoanode. Here we report that amorphous TiO 2 ( α -TiO 2 ) be used as passivator to modify the surface states of WO 3 nanoflakes film for improving its PEC water oxidation performance. In comparison with bare WO 3 film, the α -TiO 2 -coupled WO 3 ( α -TiO 2 /WO 3 ) film is of higher PEC water oxidation activity and stability. The photocurrent on α -TiO 2 /WO 3 film photoanode is improved by 2 times that reached 1.4 mA/cm 2 in 0.1 M Na 2 SO 4 solution at 0.8 V ( vs. SCE). After α -TiO 2 coupling, the UV–vis absorption edge and intensity of WO 3 film do not change obviously, but the formation and oxidation kinetics of H 2 O 2 on WO 3 photoanode are modified. The density functional theory calculations indicate the monoclinic WO 3 (002) has a surface energy of 1.17 J/m 2 , whereas the α -TiO 2 /WO 3 (002) with a much lower surface energy of 0.3 J/m 2 . Additionally, the length of Ti O bond of α -TiO 2 is changed from the initial 1.929 Å to a shorter length of 1.886 Å and a longer length of 2.290 Å in α -TiO 2 /WO 3 (002) through the O 2- -W 6+ bonding effect at α -TiO 2 /WO 3 interface. Therefore, the enhanced PEC water oxidation performance on α -TiO 2 /WO 3 film can be attributed to that α -TiO 2 passivates the surface states of WO 3 nanoflakes film, and the formation of H 2 O 2 from the photoexcited-electrons/dissolved-oxygen route is depressed and the PEC oxidation of H 2 O 2 is accelerated.
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BIORESOURCE TECHNOLOGY
·
2024
·
IF 9.7
Ziyu Jia,Jun Hu,Ping Lu,Yunjun Wang
Carbon quantum dots (CQDs) were successfully synthesized from carbohydrate-rich residue of birch obtained following the lignin-first strategy. The optical and physicochemical properties of the CQDs were studied, along with their potential for photocatalytic pollutant degradation. By combining solvothermal and chemical oxidation methods, the product yield of CQDs from carbohydrate-rich residue reached 8.1 wt%. Doping nitrogen enhances the graphitization of CQDs and introduces abundant amino groups to the surface, thereby boosted the quantum yield significantly from 8.9 % to 18.7 %-19.3 %. Nitrogen-doped CQDs exhibited efficient photocatalytic degradation of methylene blue, reaching 37 % within 60 min, with a kinetic degradation rate of 0.00725 min −1 . This study demonstrates that carbohydrate-rich residue obtained from lignin-first strategy are ideal precursors for synthesizing CQD with high mass yield and quantum yield by combining solvothermal treatment and chemical oxidation methods, offering a novel approach for the utilization of whole biomass components following the lignin-first strategy.
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Advanced Energy Materials
·
2024
·
IF 24.4
Qiaowei Lin,Jiaxing Liang,Ruopian Fang,Changlong Sun,Aditya Rawal,Jun Huang,Quan-Hong Yang,Wei Lv,Da-Wei Wang
Electrocatalysts can optimize the sulfur/sulfide reaction kinetics in Li–S batteries to compete with the loss of lithium polysulfides (LiPSs) caused by the shuttling effect. However, the design rationale of electrocatalysts to drive roundtrip sulfur/sulfide conversion is lacking. Here, pairing Lewis acidic and Lewis basic active sites to reach collective adsorption of LiPSs and simultaneous activation of electrophiles and nucleophiles in LiPSs is proposed. This concept is validated by doping polyaniline with protonated metatungstate anions, which enables reduced activation energies for both sulfur reduction reaction and sulfide oxidation reaction and results in significantly improved kinetics. Such electrocatalysts enable a Li–S battery to reach a low capacity-decay rate of 0.029% per cycle for 1000 cycles. This work would offer insights into battery technologies where sulfur electrocatalysis will play pivotal roles.
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