Journal of Materials Chemistry A
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2019
·Vol. 7
·期 8
·3863-3873
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IF 10.733
Kewei Yang,Xiaoyu Chen,Zhenhuan Zheng,Jiaqi Wan,Miao Feng,Yan Yu
TiO2 nanocrystal (NC)-based photoreversible color switching (PCS) materials, which are capable of actively responding to external light, have significant potential for use in printable rewritable paper in the creation of sustainable technologies. Reductive TiO2 NCs with high hole-scavenging capabilities can be obtained by surface disorder or lattice distortion, but achieving an optimum balance between them is still a great challenge to enable simultaneous retention of the photoreduction performance and visible light catalytic ability of the TiO2 NCs. Here, we demonstrated solvent-controlled synthesis of interstitial Sn2+-doped TiO2 NCs and investigated the effects of solvent-induced surface disorder and doping-induced lattice distortion on the PCS properties of the TiO2 NCs. The midgap state produced by surface disorder combines with the energy level produced by the interstitial Sn2+ dopants in TiO2 NCs to become the main center for photogenerated electron transfer. Thus, efficient PCS was achieved, with the number of switching cycles greatly increased. The ethylene glycol-synthesized TiO2 NCs with a Sn2+-doping concentration of ca. 3% are the most favorable catalyst for achieving PCS performance. The process of PCS can be repeated 48 times without any rest. The results of this work suggest an approach to the design and preparation of PCS materials that exhibit excellent scalability and outstanding reversible performance by using colloidal NCs with optimized surface composition, lattice structure, and particle size as key-functional photocatalysts.
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JOURNAL OF POWER SOURCES
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2019
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IF 7.467
Hao Feng,Xiaohong Jiao,Rong Chen,Xun Zhu,Qiang Liao,Dingding Ye,Biao Zhang,Wei Zhang
In this work, the nitrogen-doped TiO 2 photocatalyst is synthesized and applied in a microfluidic all-vanadium photoelectrochemical cell for enhancing the solar energy storage. The use of the nitrogen-doped TiO 2 photoanode and the minimization design can ensure the visible-light response, increased specific surface area, vigorous pore structure and enhanced photon and mass transport as well as more uniform light distribution. Various characterizations are performed to evaluate the developed photocatalyst and microfluidic all-vanadium photoelectrochemical cell. The results confirm that the developed nitrogen-doped TiO 2 photoanode can provide both the extended absorption spectrum and the small anatase crystal size as well as the obviously enlarged specific surface area with plentiful pore structure. Because of these merits, the microfluidic all-vanadium photoelectrochemical cell with the nitrogen-doped TiO 2 photoanode yield the average photocurrent density of 0.103 mA/cm 2 during the long-term operation, which is much higher than those with the un-doped TiO 2 photoanode (0.086 mA/cm 2 ) and commercial P25 TiO 2 photoanode (0.073 mA/cm 2 ), presenting 19.8% and 41% improvements, respectively. The results demonstrate not only the promotion of the vanadium reversible redox pairs conversion but also the inherently excellent stability by the nitrogen-doped TiO 2 photoanode.
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Nanomaterials
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2018
·Vol. 8
·期 11
·937
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IF 3.504
Haiyan Yang,Liang Jiang,Yizhou Li,Guoqing Li,Yepeng Yang,Jiao He,Jiaqiang Wang,Zhiying Yan
In sharp contrast to conventional photosensitization methods in which the organic pigments were often adsorbed, herein we present a study on natural vegetable pigment inserted TiO2aerogel nanocomposites and we directly use red cabbage anthocyanin (RCP) as a structure-directing agent. It was found that pure TiO2aerogel nanocomposite did not exhibit any meaningful activity for photocatalytic reduction of Cr(VI). However, the photocatalytic reduction activity was greatly improved by the RCP inserted TiO2aerogel nanocomposites under visible-light irradiation, which was approximately 2- and 12.3-fold higher than that of TiO2aerogel conventionally photosensitized by RCP and pure TiO2aerogel nanocomposites, respectively. It also exhibited good stability and could be reused at least three times without losing a significant amount of its activity.Keywords:Red cabbage pigment;anthocyanin;TiO2aerogel;photocatalytic activity
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Analytical Methods
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2018
·Vol. 11
·期 2
·171-178
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IF 2.073
Renxuan Liu,Tao Sha,Bei Nie
In vivo analyzing chemical significance under human skin has impinged a formidable challenge upon regular optical methods due to its intrinsic opaque property. With analogy to a needle biopsy, conceptually and practically, here, we fabricated a “needle-like” nanopore-embellished TiO2 column through electrochemistry directed etching, intriguingly serving as hundreds of thousands of liquid containers, perpendicular to the needle axle. A silver nanostructure synthesized in situ within the nanotube array gives rise to an opportunity for enhanced Raman detection to profile the extracts with excellent sensitivity and considerable spatial resolution, delineating the molecular information in depth. This SERS-active needle, which combined the functions of liquid biopsy and optical detection can penetrate the upper skin layer with minimal invasion and obviation of the extra step for the mass-limited sample transferring, unraveling the chemical insights underneath the opaque materials.
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Environmental Science-Nano
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2019
·Vol. 6
·期 6
·1740-1753
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IF 7.704
Tong Li,Zelin Shen,Yiling Shu,Xuguang Li,Chuanjia Jiang,Wei Chen
Thermal treatment is one of the most common and facile approaches for defect engineering of semiconductor nanomaterials for enhanced photocatalytic activities. Thus far, little is known about how exposed facets, an intrinsic nanomaterial property, may affect defect generation of widely used semiconductor nanomaterials, e.g., titanium dioxide (TiO2). Here, we synthesized two anatase TiO2 materials with different predominantly exposed facets (i.e., {101} and {010} facets, respectively), and manipulated the defects by calcination at 500 °C under an air or argon atmosphere. Through Raman, electron paramagnetic resonance, UV-vis, and X-ray photoelectron spectroscopy analyses, we demonstrated that the change of surface defect content was facet-dependent. Calcination in argon consistently increased the surface defect content for both materials, arising from the dissociation of surface oxygen atoms and removal of surface hydroxyl groups. In comparison, calcination in air decreased the surface defect content of the {101}-faceted material but increased that of the {010}-faceted material. This discrepancy was likely because, compared with the {101} facets, the {010} facets can lose surface oxygen more easily and contain a greater amount of surface hydroxyl groups. Accordingly, for the {010} facets the formation of surface defects can outcompete the annealing of defects, which occurs during thermal treatment in air. Photoluminescence analysis, electrochemical impedance spectroscopy and photocatalytic activities towards bisphenol A, Rhodamine B and hexavalent chromium degradation were consistent with the changes of defect content of the TiO2 materials, corroborating that the altered defect properties were mainly associated with surface rather than bulk defects. The findings of this work may have important implications for photocatalyst design via defect engineering.
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Catalysts
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2019
·Vol. 9
·期 4
·345
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IF 3.444
Nan-Quan Ou,Hui-Jun Li,Bo-Wen Lyu,Bo-Jie Gui,Xiong Sun,Dong-Jin Qian,Yanlin Jia,Xianying Wang,Junhe Yang
Interfacial charge transfer is crucial in the efficient conversion of solar energy into fuels and electricity. In this paper, heterojunction composites were fabricated, comprised of anatase TiO2with different percentages of exposed {101} and {001} facets and nitrogen-doped quantum dots (NGQDs) to enhance the transfer efficiency of photo-excited charge carriers. The photocatalytic performances of all samples were evaluated for RhB degradation under visible light irradiation, and the hybrid containing TiO2with 56% {001} facets demonstrated the best photocatalytic activity. The excellent photoactivity of TiO2/NGQDs was owed to the synergistic effects of the following factors: (i) The unique chemical features of NGQDs endowed NGQDs with high electronic conductivities and provided its direct contact with the TiO2surface via forming Ti–O–C chemical bonds. (ii) The co-exposed {101} and {001} facets were beneficial for the separation and transfer of charge carriers in anatase TiO2. (iii) The donor-acceptor interaction between NGQDs and electron-rich {101} facets of TiO2could remarkably enhance the photocurrent, thus hindering the charge carriers recombination rate. Extensive characterization of their physiochemical properties further showed the synergistic effect of facet-manipulated electron-hole separation in TiO2and donor-acceptor interaction in graphene quantum dots (GQDs)/TiO2on photocatalytic activity.Keywords:electron transfer;graphene quantum dots;heterojunction;photocatalysis;TiO2
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APPLIED CATALYSIS B-ENVIRONMENTAL
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2019
·
IF 14.229
Xiaoqing Gao,Shanhui Zhu,Mei Dong,Jianguo Wang,Weibin Fan
Highly efficient synthesis of valuable γ-valerolactone (GVL) by levulinic acid (LA) hydrogenation is still a challenge for Ru-based catalysts under mild condition. In this work, we have reported that ultrathin TiO 2 nanosheets supported Ru nanoparticles showed extraordinarily high catalytic activity, GVL yield (99.1%) and reusability owing to the formation of Ru O Ti interfacial structure. The turnover frequency (TOF) reached as high as 19,045 h −1 at 100 °C, much higher than those of Ru/SiO 2 , Ru/GO, Ru/MoS 2 , and commercial Ru/C. DFT calculation elucidates that the dominant reaction pathway of LA hydrogenation to GVL is preferentially hydrogenated to CH 3 CHOCH 2 CH 2 COOH*, followed by cyclization to CH 3 (OH)C 4 OH 4 OH* (GVL − OH) and final dehydroxylation, irrespective of surface structure. Compared to Ru (0 0 2) facet, Ru/TiO 2 interfacial structure changes the rate-determining step from initial hydrogenation to cyclization, which greatly declines the activation barrier from 0.81 eV to 0.48 eV.
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APPLIED SURFACE SCIENCE
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2019
·
IF 5.155
Dan Yang,Yufeng Ni,Xinxin Kong,Hao Xue,Wenli Guo,Liqun Zhang
Recently, dopamine and its secondary function are being used as the intermediate to tailor the surface molecular structure of high-dielectric-constant nanoparticles , which improves interfacial interaction of dielectric elastomer (DE) composites, due to their versatile adhesion properties. However, the high-cost of dopamine limits the large-scale applications of DE. Herein, a mussel-inspired modification of TiO 2 nanoparticles is presented to prepare high-performance natural rubber (NR) DE composites by replacing dopamine with cheaper poly(catechol/polyamine) (PCPA). First, the TiO 2 nanoparticles were deposited with PCPA. Then, the PCPA-coated TiO 2 nanoparticles were further grafted with γ-methacryloxypropyl trimethoxy silane (KH570), which contains double bonds and denoted as TiO 2 -PCPA-KH570. Owing to the presence of C C bonds, the TiO 2 -PCPA-KH570 nanoparticles participated in the vulcanization of NR and the TiO 2 -PCPA-KH570/NR composites exhibited enhanced filler dispersion and interfacial interaction, leading to the improved mechanical, dielectric, and electromechanical properties. Furthermore, the 10 phr TiO 2 -PCPA-KH570/NR composite resulted in the largest actuated strain of 12.3%, which is ~2 times higher than that of the largest actuated strain of pure NR (6.0%). The present study provides a high-efficient and cost-effective route to obtain DEAs with enhanced electromechanical properties.
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PHYSICAL CHEMISTRY CHEMICAL PHYSICS
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2019
·Vol. 21
·期 24
·12850-12858
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IF 3.567
Xin Jiang,Qinqin Sang,Ming Yang,Juan Du,Weie Wang,Libin Yang,Xiaoxia Han,Bing Zhao
The exploitation of new types of non-metal surface-enhanced Raman scattering (SERS) substrates with high performances and the exploration of enhancement mechanisms are of vital importance for the development of the SERS technology due to its potential prospects in both the spectroscopy and material fields. Here, a magnetic SERS-active substrate hybridized by reduced graphene oxide (rGO), TiO2 and Fe3O4 (rGO–TiO2–Fe3O4) was successfully prepared via the combination of a simple sol-hydrothermal method and a co-precipitation method. The as-synthesized rGO–TiO2–Fe3O4 nanohybrid not only exhibited outstanding SERS detection ability with high sensitivity and spectral reproducibility, but also could be recycled with high stability based on its self-cleaning capacity and magnetism. Exploiting these features, it could be used for the SERS detection of 4-mercaptobenzoic acid (4-MBA), 4-mercaptopyridine (4-MPy), 6-mercaptopurine monohydrate (6-MP), 1,2-di(4-pyridyl) ethylene (BPE) and p-aminobenzoic acid (PABA) with the detection limits of 1.0 × 10−10, 1.0 × 10−8, 1.0 × 10−10, 1.0 × 10−10 and 1.0 × 10−9 mol L−1, respectively; these are the highest SERS sensitivity values among those reported for semiconductor substrates and are even lower than that of noble metal substrates. Meanwhile, an SERS enhancement mechanism from the synergistic effects of the rGO, TiO2 and Fe3O4 components was proposed to explain the observed considerable SERS enhancement on rGO–TiO2–Fe3O4.
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JOURNAL OF NANOPARTICLE RESEARCH
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2019
·Vol. 21
·期 6
·1-17
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IF 2.009
An Mingze,Li Li,Zhang Jingjing,Zhao Lijie,Yang Changlong
In this paper, a three-dimensional ordered hollow sphere (3DOH) structure composite Pt/TiO 2 -ZrO 2 was prepared by using polystyrene (PS) colloidal spheres as the template and combining with two-step vacuum impregnation method, of which the composition, crystalline structure, morphology, and surface physicochemical properties were characterized by X-ray diffraction (XRD), UV-vis diffuse reflectance (UV-vis/DRS), photoluminescence (PL), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HRTEM), and nitrogen adsorption-desorption measurements. The results illustrate the crystal type of 3DOH Pt/TiO 2 -ZrO 2 is mainly anatase TiO 2 and tetragonal ZrO 2 phase, which exhibits a three-dimensional ordered hollow sphere structure. Hollow spheres are arranged orderly; moreover, the composite shows a strong absorption in the visible region due to the effect of surface plasmon absorption (SPA) after doping Pt nanoparticles. Meanwhile, the photocatalytic activity of 3DOH Pt/TiO 2 -ZrO 2 was investigated by using Congo red as the model molecule. The results show that 3DOH Pt/TiO 2 -ZrO 2 has good photocatalytic activity under multi-modes photocatalytic experiments, and its activity is higher than that of P25, ZrO 2 , and other Pt/TiO 2 -ZrO 2 not treated by PS colloidal spheres. In addition, the total amount of hydrogen production of 3DOH Pt/TiO 2 -ZrO 2 is 100 times as much as the commercial P25 in the photocatalytic hydrogen evolution experiment (8 h), which shows an excellent photolysis of water hydrogen production activity.
The three-dimensional ordered hollow sphere composite 3DOH Pt/TiO 2 -ZrO 2 was prepared by using polystyrene colloidal spheres (PS) as the template and combining with the two-step vacuum impregnation method, which had both good photocatalytic activity under multi-modes and ability on photocatalytic hydrogen evolution.
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JOURNAL OF MATERIALS SCIENCE
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2019
·Vol. 54
·期 10
·7834-7849
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IF 3.442
Dong Xuejun,Wu Keliang,Zhu Weifang,Wu Pengcheng,Hou Juan,Wang Zhaoxiong,Li Ran,Wu Jianning,Liu Zhiyong,Guo Xuhong
As a strong oxidizing pollutant, NO 2 can cause fire or even explosion. People living in atmosphere containing NO 2 for a long time will significantly affects human health. In this work, we developed a Schottky heterojunction sensor modified by g-C 3 N 4 quantum dots (g-C 3 N 4 QDs) and rGO deposited on TiO 2 nanotubes (TNTs) arrays. This sensor showed high response and extremely fast response/recovery time as well as excellent detection of ppb level of NO 2 at room temperature. TNTs were obtained using a one-step anodic oxidation process. TNTs were modified with g-C 3 N 4 QDs and rGO using quasi -CVD method and cyclic voltammetry during in situ electrodeposition, respectively. TNTs/g-C 3 N 4 QDs/rGO Schottky heterojunction sensor exhibited high sensitivity to 10 ppm of NO 2 (response equal to 15982) at room temperature. Below 15 ppb, sensing response also can reach 127. Sensor response was very fast and increased to 15982 in just 2 s when exposed to 10 ppm of NO 2 after which it recovers 90% within 1.16 s. This work clarified the influence of abundant oxygen vacancies (VO · ) in TNTs and photogenerated electrons on TNTs/g-C 3 N 4 QDs/rGO nanostructures as well as their sensing performances. Our experimental details demonstrated that Schottky barrier was established between TNTs and rGO, which was very beneficial for ppb-level NO 2 detection at room temperature.
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CATALYSIS TODAY
·
2019
·
IF 4.888
Lina Chi,Yingjia Qian,Junqiu Guo,Xinze Wang,Hamidreza Arandiyan,Zheng Jiang
Membrane fouling due to superhydropobicity of polytetrafluoroethylene ultrafiltration membranes (PTFE UFMs) represents a grand challenge for their practical applications in diverse water treatment industries. Surface immobilisation of hydrophilic and chemically stable inorganic metal oxides (TiO 2 , ZrO 2 , etc) has been developed to improve hydrophilicity of the PTFE UFMs, though they still suffer from expensive and repeating regenerations once fouled. To address such issues, we strive to firmly immobilize g-C 3 N 4 modified TiO 2 (g-C 3 N 4 /TiO 2 , hereafter CNTO) onto PTFE UFM via a facile plasma-enhanced surface graft technique using polyacrylic acid (PAA) as a bridging agent. As reported here, the obtained CNTO/PAA/PTFE UFM shows much smaller surface water contact angle (WCA) of 62.3° than that of bare PTFE UFM(115.8°), leading to enhanced water flux of 830 L m −2 h -1 in the initial ultrafiltration of modelled waste-water containing methylene blue (MB). The CNTO/PAA/PTFE UFM is highly resistant to fouling in the prolonged filtration of 1000 mg/L bovine serum albumin (BSA) solution, while the fouled CNTO/PAA/PTFE UFM is able to regenerate rapidly under either UV or visible-light irradiation. The enhanced performance of the novel CNTO/PAA/PTFE UFM is reasonably attributed to its high wettability and robust photocatalytic activity of the g-C 3 N 4 /TiO 2 coating that follows different self-cleaning mechanisms under UV and visible light irradiations.
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