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Journal ArticleDOI: 10.1039/D0TA12101K

The crystalline/amorphous stacking structure of SnO2 microspheres for excellent NO photocatalytic performance

02 Mar 2021-Journal of Materials Chemistry (Royal Society of Chemistry (RSC))-Vol. 9, Iss: 8, pp 5000-5006
Abstract: Surface amorphization via a crystalline/amorphous core–shell structure is known to be an effective approach to construct a high-efficiency photocatalyst. It enables decreasing of the bandgap of the crystalline core and facilitates rapid carrier transmission between the core and shell. However, this kind of structure induces light blocking for the crystalline core that results in fewer photogenerated carriers. In this work, we have fabricated SnO2 microspheres with a novel crystalline/amorphous stacking structure that has a significant effect on photocatalytic NO removal under visible light irradiation. The increase in the NO removal photocatalytic performance is attributed to the increased charge separation efficiency at the crystalline/amorphous interface arising from the built-in electric field between the amorphous and crystalline regions. Moreover, the crystalline/amorphous stacking structure can inhibit surface absorption competition between O2 and NO. Such a process contributes towards the generation of more oxygen active species which could oxidize NO to NO3−. This work demonstrates that the utilization of the crystalline/amorphous stacking structure provides a new strategy to manipulate the charge transport and promote the photocatalytic performance for a high-efficiency photocatalytic material.

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Topics: Amorphous solid (59%), Stacking (52%), Photocatalysis (51%)
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9 results found


Open accessJournal ArticleDOI: 10.1016/J.MATDES.2021.109542
Zou Xinxin1, Yang Yanling1, Chen Huajun1, Chen Huajun2  +5 moreInstitutions (5)
01 Apr 2021-Materials & Design
Abstract: Constructing a hierarchical structure with tunable pore size is a practical method to improve the capacity of photocatalytic hydrogen production of catalysts. In this work, titanium dioxide/graphitic carbon nitride (TiO2/g-C3N4) nanofibers with hierarchical meso/macro-porous structure are fabricated by combining a one-step electrospinning method and calcination process, in which the hierarchical meso/macro-porous structure is developed by introducing polyvinylpyrrolidone and liquid paraffin into the electrospinning solution. Comprehensive characterizations reveal that the hierarchical meso/macro-porous TiO2/g-C3N4 nanofibers have improved ultraviolet-visible light absorption, the separation efficiency of carriers, and photocatalytic performance. The photocatalytic H2 evolution is up to 1202 μmol g−1 in 7 h, which is better than those of corresponding TiO2/g-C3N4 photocatalysts previously reported. This work provides a new strategy to build a hierarchical meso/macro-porous nanofiber and an ideal solution to improve the hydrogen production of TiO2/g-C3N4.

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Topics: Nanofiber (56%), Graphitic carbon nitride (55%), Liquid paraffin (54%) ... read more

8 Citations


Journal ArticleDOI: 10.1016/J.JCIS.2021.02.079
Bi Yaxin1, Yang Yanling1, Xiaolei Shi2, Feng Lei1  +7 moreInstitutions (3)
Abstract: The van der Waals (vdW) integration enables to create heterostructures with intimate contact and bring new opportunities. However, it is not confined to layered materials but can also be generally extended to 3D materials. Multidimensional Bi2O3/BiVO4@graphene oxide (GO) van der Waals heterostructures are synthesized by one-pot wet chemistry method. Bi2O3/BiVO4 composite nanoparticles are self-assembled with GO framework by vdW interaction to form vdW heterostructures, in which GO framework allows short electron transport distance and rapid charge transfer and provides massive reactive sites. Such self-assembled heterostructures show a superior high photoactivity towards oxygen evolution with an enhanced oxygen generation rate of 1828 µmol h−1 g−1, nearly 3 times than that of pure BiVO4, attributed to the accelerated charge separation and transfer processes of Bi2O3/BiVO4@GO vdW heterostructures. This study indicates that our strategy provides a new avenue towards fabricating multi-dimensional vdW heterostructures and inspiring more innovative insights in oxygen evolution field.

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Topics: van der Waals force (55%)

2 Citations


Journal ArticleDOI: 10.1039/D1NJ01345A
Abstract: Simple chemical synthesis is highly efficient to develop metal oxide composites as active electrode materials for an electrochemical sensor displaying enhanced catalytic sites, fast kinetics, and easy accessibility to target molecules. In this work, a cobalt oxide/tin oxide (Co3O4/SnO2) composite was prepared by a facile co-precipitation method and employed for the voltammetric determination of ornidazole (ODZ). The structural and morphological properties of the as-synthesized materials were studied through XRD, FT-IR, BET, FE-SEM, TEM, and XPS analyses. The electrochemical activity was investigated using cyclic voltammetric (CV) and linear sweep voltammetric (LSV) techniques. The electrochemical signal shows that the modified glassy carbon electrode (Co3O4/SnO2/GCE) revealed superior sensing ability in rapid ODZ detection compared to a single component of Co3O4 or SnO2. The performance was investigated over a wide linear range of 0.2 to 1185.8 μM with a low detection limit of 0.059 μM for ODZ, respectively, at a low-cost Co3O4/SnO2 modified electrode. Good selectivity was observed in the presence of NFT, 2-NA, and Cd2+ by the ODZ sensor. Furthermore, the excellent stability, repeatability, and reproducibility suggest that the constructed electrode based on Co3O4/SnO2/GCE is promising for real-time application in water samples.

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Topics: Electrochemical gas sensor (58%), Tin oxide (56%), Cobalt oxide (55%) ... read more

2 Citations


Journal ArticleDOI: 10.1016/J.JMST.2021.05.009
Chen Huajun1, Chen Huajun2, Yang Yanling1, Zou Xinxin1  +4 moreInstitutions (4)
Abstract: The recycling technology of photocatalyst powdery has hardly been mature in the photocatalytic oxidation so far. In this work, the hollow TiO2 microspheres with an appropriate thickness are confined in carbon microspheres (CMSs) to form hollow TiO2@CMSs, which are physically integrated with carbon-fiber textile by van der Waals (vdW) interactions to generate separable and recyclable hollow TiO2@CMSs/carbon-fiber vdW heterostructures. Such separable and recyclable heterostructures show remarkable oxidation of 2,4-dinitrophenol. From our detailed characterization and density functional theory (DFT) calculations, we found that carbon fiber can trap electrons exerted from the excitation of hollow TiO2@CMSs and creates holes in hollow TiO2 microspheres, which endow the carbon fiber with photoelectric activity through coherent charge injection. This study indicates that our general strategy for the fabrication of hollow TiO2@CMSs/carbon-fiber vdW heterostructures can be used as separable and recyclable photocatalyst and photoelectrocatalyst with potential industrial applications in environment-related fields.

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Topics: van der Waals force (50%)

1 Citations


Journal ArticleDOI: 10.1016/J.CHEMOSPHERE.2021.131692
01 Jan 2022-Chemosphere
Abstract: Removal of toxic air and water dissociation in the environment has become a major challenging issue throughout the world. Mixed phase rutile-anatase titanium dioxide catalysts are very effective in photocatalysis and have been studied extensively. However, the mechanism causing this effect and band alignment of the two phases are not fully understood. Pointing to the issue, we have designed one-dimensional mixed-phase TiO2 and introduced defects near the valence band. Experimental results showed that band alignment between two phases, up-shift of the band edge, and optimum anatase percentage play a key role in the enhancement of the photocatalytic activity. We predicted shifts in band edge originating from surface electric dipole layer induced by defects.

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Topics: Anatase (58%), Homojunction (57%), Titanium dioxide (51%)

1 Citations


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38 results found


Journal ArticleDOI: 10.1002/ADFM.200600431
Wei-Wei Wang1, Ying-Jie Zhu1, Li-Xia Yang1Institutions (1)
Abstract: ZnO–SnO2 hollow spheres and hierarchical nanosheets are successfully synthesized using an aqueous solution containing ZnO rods, SnCl4, and NaOH by using a simple hydrothermal method. The effects of hydrothermal temperature and time on the morphology of ZnO–SnO2 are investigated. The formation process of ZnO–SnO2 hollow spheres and nanosheets is discussed. The samples are characterized using X-ray powder diffraction, transmission electron microscopy, scanning electron microscopy, and UV-vis absorption spectroscopy. Both hollow spheres and hierarchical nanosheets show higher photocatalytic activities in the degradation of methyl orange than that of ZnO rods or SnO2.

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Topics: Hydrothermal circulation (52%), Methyl orange (51%)

388 Citations


Journal ArticleDOI: 10.1002/ADFM.201001251
Dae-Jin Yang1, Itai Kamienchick2, Doo Young Youn3, Avner Rothschild2  +1 moreInstitutions (3)
Abstract: This work presents a new route to suppress grain growth and tune the sensitivity and selectivity of nanocrystalline SnO2 fibers. Unloaded and Pd-loaded SnO2 nanofiber mats are synthesized by electrospinning followed by hot-pressing at 80 °C and calcination at 450 or 600 °C. The chemical composition and microstructure evolution as a function of Pd-loading and calcination temperature are examined using EDS, XPS, XRD, SEM, and HRTEM. Highly porous fibrillar morphology with nanocrystalline fibers comprising SnO2 crystallites decorated with tiny PdO crystallites is observed. The grain size of the SnO2 crystallites in the layers that are calcined at 600 °C decreases with increasing Pd concentration from about 15 nm in the unloaded specimen to about 7 nm in the 40 mol% Pd-loaded specimen, indicating that Pd-loading could effectively suppress the SnO2 grain growth during the calcination step. The Pd-loaded SnO2 sensors have 4 orders of magnitude higher resistivity and exhibit significantly enhanced sensitivity to H2 and lower sensitivity to NO2 compared to their unloaded counterparts. These observations are attributed to enhanced electron depletion at the surface of the PdO-decorated SnO2 crystallites and catalytic effect of PdO in promoting the oxidation of H2 into H2O. These phenomena appear to have a much larger effect on the sensitivity of the Pd-loaded sensors than the reduction in grain size.

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Topics: Crystallite (55%), Calcination (54%), Grain growth (54%) ... read more

332 Citations


Journal ArticleDOI: 10.1016/J.APCATB.2017.08.049
Qiao Wang1, Wei Wang1, Lingling Zhong1, Dongmei Liu1  +2 moreInstitutions (2)
Abstract: Photocatalytic degradation has been unearthed as a promising strategy for environmental remediation, and the calling is endless for more efficient photocatalytic system. In this study, a novel oxygen vacancy-rich two-dimensional/two-dimensional (2D/2D) BiOCl-g-C3N4 ultrathin heterostructure nanosheet (CN-BC) is successfully prepared by a facile solvothermal method for degradation of non-dye organic contaminants. HRTEM observes the formation of heterojunction, while ESR and XPS unveil the distinct oxygen vacancy concentrations. Density functional calculations reveal that the introduction of oxygen vacancies (OVs) brings a new defect level, resulting in the increased photoabsorption. Under visible light irradiation, the OVs-rich optimum ratio of CN-BC (50CN-50BC) Exhibits 95% removal efficiency of 4-chlorophenol within 2 h, which is about 12.5, 5.3 and 3.4 times as that of pure BiOCl, g-C3N4 and OVs-poor heterostructure, respectively. The photocatalytic mechanism of OVs-rich 50CN-50BC is also revealed, suggesting that the synergistic effect between 2D/2D heterojunction and oxygen vacancies greatly promotes visible-light photoabsorption and photoinduced carrier separation efficiency with a prolonged lifetime, which is confirmed by multiple optical and electrochemical analyses, including DRS, steady-state photoluminescence spectra, electrochemical impedance spectroscopy, photocurrent response and time-resolved fluorescence spectra. This study could bring new opportunities for the rational design of highly efficient photocatalysts by combining 2D/2D heterojunctions with oxygen vacancies in environmental remediation.

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Topics: Photocatalysis (50%), Heterojunction (50%)

292 Citations


Open accessJournal ArticleDOI: 10.1016/J.NANOEN.2017.02.043
01 Apr 2017-Nano Energy
Abstract: In this report, we show that oxide battery anodes can be grown on two-dimensional titanium carbide sheets (MXenes) by atomic layer deposition. Using this approach, we have fabricated a composite SnO2/MXene anode for Li-ion battery applications. The SnO2/MXene anode exploits the high Li-ion capacity offered by SnO2, while maintaining the structural and mechanical integrity of the conductive MXene platform. The atomic layer deposition (ALD) conditions used to deposit SnO2 on MXene terminated with oxygen, fluorine, and hydroxyl-groups were found to be critical for preventing MXene degradation during ALD. We demonstrate that SnO2/MXene electrodes exhibit excellent electrochemical performance as Li-ion battery anodes, where conductive MXene sheets act to buffer the volume changes associated with lithiation and delithiation of SnO2. The cyclic performance of the anodes is further improved by depositing a very thin passivation layer of HfO2, in the same ALD reactor, on the SnO2/MXene anode. This is shown by high-resolution transmission electron microscopy to also improve the structural integrity of the SnO2/MXene anode during cycling. The HfO2 coated SnO2/MXene electrodes demonstrate a stable specific capacity of 843 mAh/g when used as Li-ion battery anodes.

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Topics: Atomic layer deposition (51%), Anode (51%), Lithium-ion battery (51%)

267 Citations


Open accessJournal ArticleDOI: 10.1002/ADMA.201706023
Guang Yang1, Guang Yang2, Cong Chen1, Cong Chen3  +13 moreInstitutions (3)
01 Apr 2018-Advanced Materials
Abstract: The carrier concentration of the electron-selective layer (ESL) and hole-selective layer can significantly affect the performance of organic-inorganic lead halide perovskite solar cells (PSCs). Herein, a facile yet effective two-step method, i.e., room-temperature colloidal synthesis and low-temperature removal of additive (thiourea), to control the carrier concentration of SnO2 quantum dot (QD) ESLs to achieve high-performance PSCs is developed. By optimizing the electron density of SnO2 QD ESLs, a champion stabilized power output of 20.32% for the planar PSCs using triple cation perovskite absorber and 19.73% for those using CH3 NH3 PbI3 absorber is achieved. The superior uniformity of low-temperature processed SnO2 QD ESLs also enables the fabrication of ≈19% efficiency PSCs with an aperture area of 1.0 cm2 and 16.97% efficiency flexible device. The results demonstrate the promise of carrier-concentration-controlled SnO2 QD ESLs for fabricating stable, efficient, reproducible, large-scale, and flexible planar PSCs.

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Topics: Quantum dot (51%), Perovskite (structure) (50%)

235 Citations


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