查找使用阿拉丁产品的科研文献

Preparation of high near-infrared reflectance mica/(Ni, Sb)-co-doped rutile yellow composite pigment via mechanochemical pretreatment and sintering

Junying Xiao,Zhidong Pan,Ti Zhang,Youjun Lu,Yanmin Wang

Mica/(Ni, Sb)-co-doped rutile yellow composite pigment with a high near-infrared reflectance was prepared via mechanochemical pretreatment and subsequent sintering. (Ni, Sb)-co-doped rutile yellow pigment was synthesized by a solid-phase method in the presence of sodium fluoride (NaF) as a mineralizer, and mica was peeled by ultrafine grinding . The pigment, mica and mica/pigment composite were characterized by X-ray diffraction, laser diffraction particle size analysis , nitrogen gas adsorption method, scanning electron microscopy, energy dispersive spectroscopy, ultraviolet–visible–near-infrared spectroscopy, CIE L * a * b * color scales, and infrared irradiation image, respectively. The results show that the temperature of synthesizing a pure rutile pigment in solid-phase reaction is reduced by 100°C due to the addition of mineralizer NaF. (Ni, Sb)-co-doped rutile pigment has better color rendering performance and near-infrared (NIR) reflectance. Ultrafine grinding produces the finer flatty mica particles with fresh reflective surfaces, thus improving NIR reflectance of peeled mica. In mica/pigment composite prepared via mechanochemical pretreatment and subsequent sintering, peeled mica has a synergistic effect on (Ni, Sb)-co-doped rutile pigment particles to further scatter near-infrared radiation through the multiple layer reflections, leading to a better heat insulation . The high near-infrared reflectance of composite pigment increases to 97.72%, and the b * value of the pigment synthesized with 1 wt% NaF is 37.77. For the irradiation infrared lamp, the surface temperature of aluminum plate coated with mica/(Ni, Sb)-co-doped rutile yellow composite pigment is 40.1 ± 0.2°C, which is lower than that of aluminum plate uncoated determined by thermal camera and thermocouple. When aluminum plate coated with mica/(Ni, Sb)-co-doped rutile yellow composite pigment is under sunshine, its surface temperature is 38.6 ± 0.2°C. In addition, the mechanism of preparing the composite pigment via mechanochemical pretreatment and subsequent sintering and the multiple structure reflection effect on peeled mica surface coated with (Ni, Sb)-co-doped rutile yellow pigment particles were also discussed.

Novel Tri-rutile Ni0.5Ti0.5TaO4 Microwave Dielectric Ceramics: Crystal Structure Chemistry, Raman Vibration Mode, and Chemical Bond Characteristic In-Depth Studies

Xiaohui Wu,Yulan Jing,Yuanxun Li,Hua Su

Here, a novel tri-rutile Ni0.5Ti0.5TaO4 ceramic configuration was first reported, and the sintering features, chemical bond theory, and microwave dielectric properties were systematically explored. Pure Ni0.5Ti0.5TaO4 ceramic with a tri-rutile structure was well sintered at 1275 °C with excellent microwave performance: εr ∼33.06, Q × f ∼14,600 GHz, and τf ∼93.95 ppm/°C. Based on the P–V–L theory, the dielectric constant was mainly affected by the formation of Ta–O bonds (∼62%) due to the larger ionic polarization and bond susceptibility. The experimental dielectric constant (33.06) was comparable to the theoretical calculation (P–V–L: 35.11). The lattice energy was also dominated by the Ta–O bond (∼71%) and the intrinsic loss properties. The τf was also affected by the [M1/M2O6] octahedral distortion. In addition, the relative density, grain size, and packing fraction also played a certain role in the microwave dielectric properties. Insights from the Raman spectroscopy revealed that the A1g mode dominated the Raman vibration at 699.44 cm–1. These results were helpful to provide ideas for novel medium dielectric constant materials and contributed to the miniaturization of microwave electronic devices.

Alcohol production from fatty acids via Ni3Fe/Rutile: Revealing the role of oxygen vacancy and metal-support electronic density characteristics

Feng Long,Shiyu Wu,Haitian Chen,Shuya Jia,Xincheng Cao,Peng Liu,Yanju Lu,Jianchun Jiang,Xiaolei Zhang,Junming Xu

Ni 3 Fe clusters anchored on rutile (R-TiO 2 ) were synthesized by hydrothermal (HT), coprecipitation (CP) and impregnation (IM) methods, and the catalytic performance of different NiFe/R-TiO 2 catalysts were investigated for hydrogenation of fatty acid into alcohol. Notably, HT-NiFe/R-TiO 2 catalyst, with the highest specific surface area and Ni 3 Fe nanoparticles dispersion, exhibited the best hydrogenation activity towards alcohol production, with complete conversion and yield reach of 92.5 % at 4 MPa H 2 , 210 ℃ and 6 h. The structure–reactivity relationship was investigated by a series of catalysts characterization, DFT calculation and corroborated through hydrogenation performance evaluations. Anchoring Ni 3 Fe clusters onto highly dispersed basic site surfaces with different Ov concentrations can change the electron distribution and strength of the metal-support interaction, causing more stable adsorption of the H and acids molecular toward fatty alcohol production. This work provides further insight into the structure–activity of NiFe/TiO 2 catalysts synthesized through different methods.

High performance and colossal permittivity of (Nb+La) co-doped rutile TiO2 ceramics induced by composition regulation

Yang Yu,Wei-Li Li,Wei-Dong Fei

One-step molten-salt synthesis of anatase/rutile bi-phase TiO2@MoS2 hierarchical photocatalysts for enhanced solar-driven hydrogen generation

Chaofeng Zhong,Wei Weng,Xinxin Liang,Dong Gu,Wei Xiao

Phase junction construction and surface modification are two practical engineering strategies towards efficient photocatalysis. In the present work, the A natase/ R utile biphasic TiO 2 nanoparticles@ M oS 2 nanosheets ( ARM ) heterojunctions were directly constructed via one-step pyrolysis of TiO(OH) 2 and (NH 4 ) 2 MoS 4 in LiCl-KCl molten salt. Phase junction is verified at the interface between anatase and rutile TiO 2 , which efficiently enhances spatial charge separation. With further incorporating MoS 2 over TiO 2 to facilitate kinetics of surface redox reactions, the ARM with an optimal MoS 2 weight ratio of 5% exhibits significantly enhanced photocatalytic activity towards solar-driven hydrogen evolution, achieving a hydrogen production rate comparable to the Pt/TiO 2 . The detailed characterization highlights the merits of molten-salt pyrolysis to modulate compositional/structural rationales of photocatalysts utilizing the synergistic effect of anatase/rutile phase junction and surface TiO 2 -MoS 2 heterojunction . The present study provides a facile approach to enable surface and interface engineering in one step.

Aggregation and transport of rutile titanium dioxide nanoparticles with montmorillonite and diatomite in the presence of phosphate in porous sand

Peng Guo,Nan Xu,Duo Li,Xinxing Huangfu,Zuling Li

Crop soil is inevitably contaminated by the excess of phosphate (P) fertilizers. A large amount of nanoparticle titanium dioxide (nTiO 2 ) entered soils as well due to the wide use of engineered nanomaterials . It is of great urgency and a high priority to investigate the mechanisms of nTiO 2 deposition with the presence of P in crop soils. This study investigated the transport behavior of (1.0 g L −1 ) rutile nTiO 2 with two representative clay particles (montmorillonite or diatomite) in the presence of P through the saturated quartz sand. In 10 mM NaCl electrolyte solution at pH 6.0, the recovery percentage of nTiO 2 was 36.3% from sand column. Nevertheless, it was reduced to 18.6% and 11.1% while montmorillonite and diatomite present in suspensions, respectively. Obviously, the improvement of nTiO 2 retention in sand was more pronounced by diatomite than montmorillonite. The likely mechanism for this result was that large aggregates were formed due to the attachment of nTiO 2 to montmorillonite and diatomite. Moreover, the surface of diatomite with the larger hydrodynamic radius was less negatively charged by comparison with montmorillonite. However, this phenomenon disappeared with the addition of P. P adsorption increases the repulsive force between particles and sand and the fast release of attached nTiO 2 -montmorillonite and diatomite from sand. The two-site kinetic retention model and the Derjaguin-Landau-Verwey-Overbeek (DLVO) theory suggested that the combination of k 1/ k 1d , k 2 and secondary minimum energy can be used to accurately describe the attachment of nTiO 2 -montmorillonite and diatomite to sand in the presence of P.

17.46% efficient and highly stable carbon-based planar perovskite solar cells employing Ni-doped rutile TiO2 as electron transport layer

Xingyue Liu,Zhiyong Liu,Bo Sun,Xianhua Tan,Haibo Ye,Yuxue Tu,Tielin Shi,Zirong Tang,Guanglan Liao

Organometal trihalide perovskite solar cells (PSCs) with carbon counter electrode (CE) have attracted tremendous interest due to their remarkable properties such as low cost and high stability. However, carbon-based PSCs always suffer from much lower power conversion efficiency (PCE) than the counterparts with noble metal cathode. Herein, we demonstrate a carbon-based planar heterojunction PSC using high-crystallinity Ni-doped rutile TiO 2 as electron transport layer (ETL) for the first time, while copper phthalocyanine (CuPc) is introduced as hole transport layer (HTL). It is found that Ni doping can shift the Fermi level of the ETL upward and increase the charge mobility of the TiO 2 film, thus enhancing the charge transport and extraction. An optimized PCE of 17.46% was obtained after 0.01 M Ni doping, comparable to or even better than devices with state-of-the-art doped Spiro-OMeTAD as HTL and Au as CE. To the best of our knowledge, this is the highest efficiency that has been reported for carbon-based PSCs. By contrast, the pristine TiO 2 -based device only displayed a PCE of 15.82%. Detailed superior capability of Ni-doped TiO 2 in facilitating charge transfer and suppressing carrier recombination are revealed by Hall effect and photoluminescence (PL) as well as electrochemical impedance spectroscopy (EIS) measurements. Furthermore, the use of highly stable CuPc and commercial carbon makes as-prepared PSCs exhibit excellent stability with no obvious decline in PCE after being stored in ambient air for 1200 h. This work presents an important step forwards to the commercialization of carbon-based PSCs with high efficiency and long-term stability.

All low-temperature processed carbon-based planar heterojunction perovskite solar cells employing Mg-doped rutile TiO2 as electron transport layer

Xingyue Liu,Zhiyong Liu,Bo Sun,Xianhua Tan,Haibo Ye,Yuxue Tu,Tielin Shi,Zirong Tang,Guanglan Liao

Electron transport layer (ETL), functioning as the electron transportation and extraction layer as well as hole-blocking layer, plays an important role in planar perovskite solar cells (PSCs). Majority of the state-of-the-art PSCs contain a TiO 2 ETL always requiring a high temperature (500 °C) treatment, which is both energy-consuming and incompatible with flexible substrates, thus hindering large-scale application in flexible devices. Here, we demonstrated a low-temperature (70 °C) solution-processed Mg-doped rutile TiO 2 as ETL in planar PSCs, while the thermal-evaporated copper phthalocyanine (CuPc) and doctor-bladed carbon were introduced as the hole transport layer (HTL) and counter electrode, respectively. The as-prepared PSC obtains a 15.73% power conversion efficiency (PCE), which is quite an excellent efficiency among carbon-based planar PSCs, getting an increase by 16% compared to the 13.56% PCE of the pristine TiO 2 -based device. The prominent increment is mainly attributed to the faster charge extraction, better electrical conductivity and suppressed charge recombination of Mg-doped TiO 2 . Besides, using highly stable CuPc and commercial carbon makes the as-prepared PSCs highly durable over 30 days when exposed to the ambient air with a relative humidity of 50%. Since all the processes are conducted under 100 °C, our work paves a way for developing cost-effective and highly stable PSCs compatible with flexible substrates.

Constructing Anatase/Rutile TiO2 Homojunction-Supported Pd Electrocatalyst via Band Alignment and Oxygen Vacancy Engineering for Direct Methanol Fuel Cells

Jun Zhang,Tiantian Peng,Lanyu Luo,Weimin Wu,Xinlan Xu,Boyu Liu,Lingying Jiang,Shi-Yu Lu,Meng Jin

Maximizing reaction kinetics of Pd catalysts for oxygen reduction reaction (ORR) while minimizing CO poisoning during methanol oxidation reaction (MOR) remains a key challenge for advancing direct methanol fuel cells (DMFCs). Herein, we synthesize an anatase/rutile TiO2 homojunction (A/R-TiO₂) through energy band alignment and oxygen vacancies engineering, providing support for Pd nanoparticles to decipher the strong correlation between this unique structure and the electrocatalytic properties of Pd/A/R-TiO₂ catalysts. Combined experimental results and theoretical calculations demonstrate that the near perfect energy band alignment and abundant oxygen vacancies in A/R-TiO₂ not only accelerate electron transfer to Pd surface, thereby maximizing reaction kinetics and catalytic efficiency, while optimize the electronic structure of Pd active sites to reduce adsorption energy of key intermediates (*OH, *CH2OH, *CO) during ORR and MOR. Consequently, the Pd/A/R-TiO₂ catalyst delivers remarkably positive E1/2 of 0.929 V and enhanced mass activity of 4.27 A mgPd-1 at 0.85 V for ORR, respectively nearly 13 and 27 times greater than those of Pt/C and Pd/C catalysts commercially available at present. The Pd/A/R-TiO₂ catalyst displays high selectivity for an effective four-electron transfer pathway, a lower H2O2 yield (1.66%), and excellent methanol crossover tolerance. Importantly, the catalyst demonstrates exceptional stability, exhibiting minimal activity decay and negligible structural degradation after 10000 cycles. Furthermore, the as-synthesized catalyst achieves superior MOR activity (4.10 A mg-1 and 8.85 A cm-2) and enhanced CO tolerance, surpassing commercial Pt/C and Pd/C catalysts. These bifunctional catalysts thus hold strong potential for large-scale and industry-orientated use of DMFCs.

Significantly Enhanced Electrostatic Energy Density of a PVDF-Based Film with [001]-Oriented Rutile TiO2 Fillers via Multilayer Interfacial Engineering

Huan Liu,Ziyue Wang,Yicheng Peng,Jiyang Xie,Wanbiao Hu

Introducing high dielectric-constant inorganic fillers into a high-broaden-strength polymer matrix is a crucial strategy to achieve a high-performance energy storage polymer composite. However, the interfacial coupling between the inorganic fillers and polymer matrix has always been a predicament for optimal performance. Herein, a multilayer interface structure, i.e., TiO2/SiO2, SiO2/polydopamine (PDA), and PDA/PVDF, are developed to resist the applied high electric field and improve the interfacial polarization simultaneously. TiO2 nanorods (NRs) with [001]-oriented rutile polymorph are synthesized by sodium dodecyl sulfate (SDS) assisted hydrothermal reaction, which is further decorated with a SiO2 layer and a subsequent PDA layer in order to incorporate well into the PVDF matrix using a solution casting process, finally forming the TiO2@SiO2@PDA/PVDF composite film. The optimal composite film incorporating [001]-TiO2 NRs exhibits an ultrahigh energy density (Ue) of 29.8 J/cm3 at a high Eb of 532 MV/m, sharply superior to the TiO2 counterpart-based films (e.g., TiO2 nanoparticle (NPs) based, and with or without the SiO2/PDA layer, which only gives a maximum Ue of 16 J/cm3 in TiO2@SiO2@PDA NPs/PVDF), and also the similarly inorganic-polymer systems previously reported. This work not only demonstrates an inorganic-polymer hybrid composite film with high electrostatic storage density but also highlights a multilayer interface structure route to alter interfacial microstructures and achieve superior energy storage performance.

Synthesis of (La + Nb) co-doped TiO2 rutile nanoparticles and dielectric properties of their derived ceramics composed of submicron-sized grains

Jingxuan Li,Yu Zeng,Yihang Fang,Nan Chen,Guoping Du,Aisheng Zhang

In this work, a sol-gel method was used to synthesize nanometer-sized rutile (La + Nb) co-doped TiO 2 powders, which were employed to prepare (La + Nb) co-doped TiO 2 ceramics. The average grain size of the (La + Nb) co-doped TiO 2 ceramics was less than 200 nm, which is much smaller than that of conventionally prepared co-doped TiO 2 ceramics generally having micron-sized grains. The effect of the (La + Nb) co-doping concentration on the microstructures and dielectric properties of the obtained ceramics was studied in detail. For a 2% co-doping concentration, it was found that the (La + Nb) co-doped TiO 2 ceramic had dielectric permittivity (εʹ) higher than 2 × 10 4 for frequency up to 1 MHz and the lowest dielectric loss (tanδ) was 0.019 at 1 kHz. The electron hopping and electron-pinned defect-dipole effect was considered as the main reasons for colossal permittivity and low tanδ. This work provides a technique for the synthesis of co-doped TiO 2 nanoparticles and preparation of submicron-grain-sized co-doped TiO 2 ceramics with good dielectric properties.

Significant enhancement of the tracking resistance of silicone rubber via promoting ceramization by platinum anchored on rutile TiO2 with oxygen vacancies

Jianxiang Xiong,Xuejun Lai,Hongqiang Li,Hao Wang,Xiangyu Su,Xingrong Zeng

The tracking resistance of silicone rubber was commonly improved by incorporating a large amount (>40 wt%) of inorganic fillers, such as aluminum hydroxide, which severely deteriorated its processability and mechanical properties. In this work, platinum-anchored TiO 2 (Pt@TiO 2 -450) was prepared by impregnating TiO 2 in H 2 PtCl 6 aqueous solution and heating at 450 ℃. It was found that the platinum-anchored rutile TiO 2 (Pt@TiO 2 -R450) and fluorophlogopite nanosheet (FPN) could synergistically promote the ceramization of silicone rubber to significantly enhance its tracking resistance. When the content of Pt@TiO 2 -R450 and FPN was 1.0 phr and 0.5 phr, respectively, the tracking resistance of SR/Pt@TiO 2 -R450 reached 1A4.5 level and the erosion ratio was 0.7%. After heating at 1000 ℃ for 1 h, the organic–inorganic conversion ratio and flexural strength were 47.1% and 7.02 MPa, respectively. High-resolution transmission electron microscopy (HRTEM), X-ray photoelectron spectroscopy (XPS) and X-ray absorption fine structure (XAFS) spectroscopy revealed that the exposed crystal plane of rutile TiO 2 in Pt@TiO 2 -R450 was (110) plane and oxygen vacancies were generated during high-temperature treatment. The oxygen vacancies could anchor Pt and suppress its aggregation at elevated temperature. Meanwhile, the electron transfer from TiO 2 to Pt reduced the oxidation state of Pt species to enhance the catalytic activity for crosslinking of silicone rubber at elevated temperature, which promoted the organic–inorganic conversion to form ceramic barrier. The skeletal support and barrier effect of FPN further improved the compactness of the ceramic barrier. As a result, the silicone rubber rapidly formed a compact SiOC-like ceramic barrier on its surface when subjected to arc discharge, which efficiently defended arc bombardment and heat transfer. Therefore, the tracking resistance of silicone rubber was significantly enhanced.