ACS Applied Materials & Interfaces
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2020
·
IF 8.758
Fang Peng,Weiwei Yu,Yue Lu,Yan Sun,Xiuli Fu,Jia ming Hao,Xin Chen,Rui Cong,Ning Dai
To verify the effect of oxygen vacancy on gas sensitivity, we have systematically investigated the gas-sensing performance of copper oxide/substoichiometric tungsten oxide (CuO/WO3–x) nanocomposite sensors. Oxygen deficiency in WO3–x facilitates the reaction of hydrogen sulfide (H2S) gas with chemisorbed oxygen species (i.e., O2–, O–, and O2–) at low temperature. The oxygen/sulphur exchange reaction between CuO and H2S in the sensing process can achieve room temperature operation of gas sensors. After the WO3–x nanorods were modified by a low content of CuO nanoparticles (Cu:W = 1:20), the sensors present an n-type sensing behavior. Their best working temperatures drop from 289 °C (or 386 °C) to 99 °C (or 70 °C) at which the responses are improved by 14 to 163 times for different x values. Among them, CuO(L)/W5O14 shows the highest sensitivity of 1575.7 to 10 ppm H2S at 99 °C and 171.5 to 10 ppm H2S at room temperature. Once WO3–x were loaded with a high concentration of CuO nanoparticles (Cu:W = 1:2), they exhibit a p-type behavior, and the optimal working temperatures reduce suddenly to room temperature at which CuO(H)/W18O49 displays the most sensitive response of 7.2 even toward trace amounts of H2S as low as 100 ppb. In addition, p-type CuO weakens the metal-like characteristics of W18O49 and such weakening effect enhances with an increase in the CuO content. Therefore, the sensing performance of the CuO/W18O49 composite is the best among the four CuO/WO3–x sensors. The two designs for low and high Cu/W molar ratios all achieve enhanced room-temperature H2S gas response, with a fast recovery time of ∼60 s under heating pulse, as well as an excellent selectivity, which makes the sensors a promising candidate for practical applications. Moreover, the micro-Raman spectra confirmed CuS formation and the thermal effect on the decomposition of CuS in the sensing process was studied.
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NEW JOURNAL OF CHEMISTRY
·
2020
·Vol. 44
·期 44
·19013-19021
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IF 3.288
Yi Zheng,Yiliang Shao,Xingzhi Jin,Min Shu,Longxiao Zhang,Chunlei Li
The contact quality of a composite is an important factor for the transfer and separation of photogenerated carriers. For this, we demonstrated a cation exchange method for the in situ construction of WO3/PbWO4 linked by WO6 octahedral crystal structure units, where WO3 was placed on the surface of PbWO4. We found that the apparent rate constant of the as-prepared WO3/PbWO4 was significantly increased (17 times higher than any single one). Our investigation indicated a remarkably enhanced photodegradation rate, originating from high contact quality. The photogenerated carriers of WO3/PbWO4 were greatly separated via the grain boundary, making WO3/PbWO4 exhibit 22 times higher photocurrent density than pristine PbWO4. Moreover, the photoelectrons and holes were separated through the high contact quality grain boundary built-in electric field, which is in accordance with the transmission path of the Z-scheme. Compared with the interface, a grain boundary is more conducive to the photocatalytic process. This study provides a feasible strategy to build a highly efficient Z-scheme photocatalyst with high contact quality grain boundary to remove organic pollutants.
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Materials Science and Engineering B-Advanced Functional Solid-State Materials
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2020
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IF 4.706
Yaru Shang,Xiaohu Cheng,Ruixia Shi,Qian Ma,Yingzi Wang,Ping Yang
The adsorption experimental results show that W 18 O 49 with oxygen vacancies not only has faster adsorption rates for MB but also has larger adsorption capacities than WO 3 . Besides, the maximum adsorption capacity of urchin-like W 18 O 49 (375.94 mg/g) is about 2.76 times of WO 3 (136.25 mg/g). However, photocatalytic results revealed that WO 3 has better photocatalytic degradation ability than W 18 O 49 . Generally, the adsorption efficiency of urchin-like W 18 O 49 (70.01%) is about 3.94 times of WO 3 (17.78%), while the photodegradation efficiency of WO 3 (62.45%) is 2.38 times of urchin-like W 18 O 49 (26.20%). Therefore, urchin-like W 18 O 49 has the best total removal efficiency, which can remove 96.21% of MB (50 ml, 90 mg/L) within 120 min. These studies emphasize the comprehensive effects of WO 3 and W 18 O 49 on dye removal from two aspects of adsorption and photocatalysis and provide strategies for the preparation of efficient dye removal materials.
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APPLIED CATALYSIS B-ENVIRONMENTAL
·
2020
·
IF 16.683
Yechen Wang,Yaru Wang,Jianjun Zhao,Min Chen,Xubo Huang,Yiming Xu
Production of H 2 O 2 via a more economic, green and safe way is challenging. In this work, we report an efficient production of H 2 O 2 from oxygen reduction reaction (ORR) in aqueous solution over a modified WO 3 with Au nanoparticles . Under visible light at wavelengths longer than 420 nm for 5 h, H 2 O 2 measured from WO 3 and Au/WO 3 were 1.07, and 177 μM, respectively. On addition of methanol, H 2 O 2 obtained from WO 3 , Au/WO 3 , and Au/SiO 2 were 8.55, 544, and 0.36 μM, respectively. Photoluminescence and electrochemical measurement revealed that there was an interfacial electron transfer from the excited WO 3 to Au, followed by two-electron reduction of O 2 on Au sites. Under visible light at wavelengths longer than 535 nm, interestingly, H 2 O 2 was also produced from Au/WO 3 (39 μM at 5 h), while the photocurrent of water oxidation on Au/WO 3 was much larger than those on Au/SiO 2 and WO 3 . Clearly, there is also an interfacial electron transfer from the plasmonic Au to WO 3 , followed by ORR to H 2 O 2 , but such a process fails when WO 3 is excited. However, the production of H 2 O 2 on Au/WO 3 was determined by several factors, including Au content, light absorption, and particle size. A maximum H 2 O 2 was observed at an initial pH 3.0 from 0.35 wt% Au/WO 3 , prepared at 400 °C. Moreover, at the same loading on WO 3 , Au was more efficient than Pd, Ag, Pt, Ni, Cu, and Co, while at the same Au loading, WO 3 was more efficient than BiVO 4 and Bi 2 WO 6 . The superior performance of Au/WO 3 is mainly due to its ability to undergo selective ORR to H 2 O 2 , and to release protons into aqueous solution protecting H 2 O 2 from decomposition.
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Advanced Composites and Hybrid Materials
·
2021
·Vol. 4
·期 4
·1330-1342
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IF 5.693
Zhang Fuhao,Cheng Wei,Yu Zhuanghua,Ge Shengsong,Shao Qian,Pan Duo,Liu Bin,Wang Xiaojing,Guo Zhanhu
A novel nanocomposite (WO 3 /UiO-66) was successfully synthesized by the microwave hydrothermal method. The influence of the W:Zr molar ratio on the WO 3 /UiO-66 structure was explored in detail, and the photocatalytic activity of the nanocomposite for photodegradation of rhodamine B (RhB) was evaluated. The WO 3 /UiO-66 with a W:Zr molar ratio of 1:5 (WO 3 /UiO-66–5) exerted the most excellent photocatalytic performance, and the photocatalytic efficiency reached 96.6% after 100 min of simulated sunlight irradiation, thereby showing a higher photocatalytic performance than pure UiO-66 or pure WO 3 . In addition, the stability and reusability of the nanocomposite were studied by cyclic experiments, and the degradation rate of WO 3 /UiO-66–5 still reached 86.6% after 5 cycles. The mechanism underlying the photocatalytic degradation of WO 3 /UiO-66 was finally studied by quenching tests, and the crucial factor in the RhB degradation was hole (h + ), and the existence of the n–n heterojunction also promotes the degradation of RhB by nanocomposites. In this work, an effective method is provided for the preparation of photocatalysts that degrade organic dyes.
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Frontiers in Chemistry
·
2019
·
IF 3.782
Shao Hongyun,Huang Minxuan,Fu Hao,Wang Shaopeng,Wang Liwei,Lu Jie,Wang Yinghui,Yu Kefu
Metal oxide hetero-nanostructures have widely been used as the core part of chemical gas sensors. To improve the dispersion state of each constituent and the poor stability that exists in heterogeneous gas sensing materials, a uniaxial electro-spinning method combined with calcination was applied to synthesize pure SnO2 and three groups of WO3/SnO2 (WO3 of 0.1, 0.3, 0.9 wt%) hetero-nanofibers (HNFs) in our work. A series of characterizations prove that the products present hollow and fibrous structures composed of even nanoparticles while WO3 is uniformly distributed into the SnO2 matrix. Gas sensing tests display that the WO3/SnO2 (0.3 wt%) sensor not only exhibits the highest response (30.28) and excellent selectivity to acetone vapor at the lower detection temperature (170°C), 6 times higher than that of pure SnO2 (5.2), but still achieves a considerable response (4.7) when the acetone concentration is down to 100 ppb with the corresponding response/recovery times of 50/200 s, respectively. Such structure obviously enhances the gas sensing performance toward acetone which guides the construction of a highly sensitive acetone sensor. Meanwhile, the enhancement mechanism of such a special sensor is also discussed in detail.
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APPLIED PHYSICS A-MATERIALS SCIENCE & PROCESSING
·
2019
·Vol. 125
·期 10
·1-8
·
IF 1.784
Cui Yongping,Shang Yaru,Shi Ruixia,Che Quande,Wang Yingzi,Yang Ping
The effects of calcination temperature, precursor content, holding time and heating rate on the morphology of WO 3 nanofibers (NFs) prepared by electrospinning technology have been investigated systematically. The X-ray diffraction (XRD) patterns using Rietveld method indicated that average crystalline sizes of nanoparticles of WO 3 NFs increase with increasing calcination temperature. Also, the crystallinity of the nanofibers increases with the rise of calcination temperature. The suitable precursor contents and holding time facilitate the formation of continuous and uniform NFs. The samples prepared by different heating rates showed that the WO 3 NFs fabricated with heating rate of 5 °C/min possess the smallest and uniform nanoparticle sizes. The X-ray diffraction (XRD) patterns using Rietveld method exhibited that different heating rate had no significant influence on the crystallinity of WO 3 NFs. Additionally, the experimental results of photocurrent responses and electrochemical impedance indicate that the WO 3 NFs prepared by different heating rate have different photoelectrochemical performances.
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APPLIED SURFACE SCIENCE
·
2020
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IF 6.182
Yulin He,Ying Li,Yaochun Liu,Nianchun Yao,Jiamei Li,Yang Liu
Inspired by the WO 3 transition metal semiconductor, a simple liquid phase WO 3 coating strategy is introduced to improve the surface stability of LiNi 0.5 Co 0.2 Mn 0.3 O 2 . The electrochemical performance of WO 3 -coated LiNi 0.5 Co 0.2 Mn 0.3 O 2 is improved at both a high cut-off voltage (4.5 V) and high temperature (50 °C). With the WO 3 (0.6 wt%) coating amount optimized, the material capacity retention is maintained at 138 mAh g −1 and 170.9 mAh g −1 at 25 °C and 50 °C after 200 cycles compared with 107.8 mAh g −1 and 143.9 mAh g −1 , respectively, for pristine NCM523. The WO 3 -coated sample also exhibits a better rate capability, maintaining 126 mAh g −1 at 25 °C in the voltage range of 3–4.5 V at the current density of 5 C. The enhanced properties of the WO 3 -coated LiNi 0.5 Co 0.2 Mn 0.3 O 2 due to the WO 3 coating layer result from the interface that prevents immediate contact between the electrolyte and the active material as well as the lower polarization and electrochemical resistance of the battery. SEM, TEM, XPS and EIS further reveal these improved electrochemical performances, which indicate the success of the approach for regenerating NCM523.
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APPLIED PHYSICS A-MATERIALS SCIENCE & PROCESSING
·
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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Catalysts
·
2019
·Vol. 9
·期 2
·187
·
IF 3.444
Pingfan Xu,Siyi Huang,Minghua Liu,Yuancai Lv,Zhonghui Wang,Jinlin Long,Wei Zhang,Haojun Fan
Semiconductor photocatalysis has received much attention as a promising technique to solve energy crisis and environmental pollution. This work demonstrated the rational design of “sandwich” WO3/rGO/SnIn4S8(WGS) Z-scheme photocatalysts for efficient purification of wastewater emitted from tannery and dyeing industries. Such materials were prepared by a combined protocol of the in situ precipitation method with hydrothermal synthesis, and structurally characterized by XRD, SEM, HRTEM, UV-vis DRS, and PL spectroscopy. Results showed that the Z-schemed nanohybrids significantly enhanced the photocatalytic activity compared to the single component photocatalysts. An optimized case of the WGS-2.5% photocatalysts exhibited the highest Cr(VI) reduction rate, which was ca. 1.8 and 12 times more than those of pure SnIn4S8(SIS) and WO3, respectively. Moreover, the molecular mechanism of the enhanced photocatalysis was clearly revealed by the radical-trapping control experiments and electron paramagnetic resonance (ESR) spectroscopy. The amount of superoxide and hydroxyl radicals as the major reactive oxygen species performing the redox catalysis was enhanced significantly on the Z-scheme WGS photocatalysts, where the spatial separation of photoinduced electron–hole pairs was therefore accelerated for the reduction of Cr(VI) and degradation of Rhodamine B (RhB). This study provides a novel strategy for the synthesis of all-solid-state Z-scheme photocatalysts for environmental remediation.Keywords:WO3/rGO/SnIn4S8;Z-scheme photocatalyst;active oxygen species;photocatalytic Cr (VI) reduction;rGO
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TALANTA
·
2019
·
IF 4.916
Zhihong Li,Xinyi Liu,Xiao-Hua Liang,Jianhai Zhong,Liangqia Guo,Fengfu Fu
Two-dimensional WO 3 nanosheets were prepared by ultrasonic exfoliation of bulk WO 3 ·2H 2 O in water and characterized by transmission electron microscopy, atomic force microscopy , X-ray diffraction, X-ray photoelectron spectroscopy, Raman, dynamic light scattering . The nanosheets were discovered to possess the peroxidase-like catalytic activity, which can catalyze the oxidation of 3, 3′, 5, 5′-tetramethylbenzidine by H 2 O 2 . The catalytic mechanism was also investigated by the scavenger experiments. Taking advantage of the peroxidase-like activity of WO 3 nanosheets, a facile colorimetric method for xanthine was developed by combining the oxidation reaction of xanthine catalyzed by xanthine oxidase. The linear range for xanthine was ranged from 25 to 200 μmol L −1 . The limit of detection for xanthine was 1.24 μmol L −1 . The colorimetric method was applied to determine xanthine in urine samples.
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ELECTROCHIMICA ACTA
·
2019
·
IF 5.383
Chenzheng Hua,Guangzhong Yuan,Ziqiang Cheng,Hong Jiang,Gang Xu,Yong Liu,Gaorong Han
TiO 2 nanocrystals embedded amorphous WO 3 electrochromic films have been successfully fabricated with a facile one-step solution process. The structure and electrochromic properties of composite films were studied by transmission electron microscope, scanning electron microscope, X-ray diffraction, Raman spectroscopy, and electrochemical methods. The results show that anatase TiO 2 nanocrystals with a size of about 5–10 nm were homogeneously embedded in the amorphous WO 3 matrix (TiO 2 @WO 3 ). Compared with pure WO 3 film, the electrochromic performances of TiO 2 @WO 3 are evidently enhanced. The further electrochemical analysis indicates that the enhancement may be mainly ascribed to the reconstruction of amorphous WO 3 matrix with the emerging interfaces between nanocrystals and amorphous matrix. And the extremely high value of the coloration/bleaching reversibility is associated with the suppressing effect of TiO 2 nanocrystals upon the Li + trapping in WO 3 matrix.
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