ADVANCED FUNCTIONAL MATERIALS
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2019
·Vol. 29
·期 46
·1905694
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IF 15.621
Lin Yang,Chunxiang Dall'Agnese,Yohan Dall'Agnese,Gang Chen,Yu Gao,Yoshitaka Sanehira,Ajay Kumar Jena,Xiao-Feng Wang,Yury Gogotsi,Tsutomu Miyasaka
MXenes are a large and rapidly expanding family of 2D materials that, owing to their unique optoelectronic properties and tunable surface termination, find a wide range of applications including energy storage and energy conversion. In this work, Ti 3 C 2 T x MXene nanosheets are applied as a novel type of electron transport layer (ETL) in low-temperature processed planar-structured perovskite solar cells (PSCs). Interestingly, simple UV-ozone treatment of the metallic Ti 3 C 2 T x that increases the surface Ti O bonds without any change in its bulk properties such as high electron mobility improves its suitability as an ETL. Improved electron transfer and suppressed recombination at the ETL/perovskite interface results in augmentation of the power conversion efficiency (PCE) from 5.00% in the case of Ti 3 C 2 T x without UV-ozone treatment to the champion PCE of 17.17%, achieved using the Ti 3 C 2 T x film after 30 min of UV-ozone treatment. As the first report on the use of pure MXene layer as an ETL in PSCs, this work shows the great potential of MXenes to be used in PSCs and displays their promise for applications in photovoltaic technology in general.
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JOURNAL OF ALLOYS AND COMPOUNDS
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2020
·
IF 4.65
X.Q. Liu,C.J. Li,X. You,Z.Y. Xu,X. Li,R. Bao,J.M. Tao,J.H. Yi
Carbon nanotube reinforced aluminum matrix (CNT/Al) composites with various microstructures were fabricated by powder metallurgy via introducing nano-sized and micron-sized Ti powders into the CNT-Al system. The size-dependent effects of Ti powders on the microstructure evolution and mechanical properties were further investigated. The results reveal that the best enhancement (∼51% of UTS) was obtained by adding 80 nm sized Ti powders into the CNT/Al composite compared with the composite without Ti addition, which mainly derives from the synergistic strengthening of the homogenously dispersed CNTs, a large quantity of in-situ formed nano-sized TiAl 3 particles and fine grains. Meanwhile, it is also noted that the addition of micron-sized Ti powders can help the CNT dispersion in powder fabrication stage, and subsequently in-situ formed core-shell structured particles with different interface reaction degree in the Al matrix. Among them, 1 μm was determined to be the optimal size of Ti for the maximum formation of core-shell structured particles, which best exploits the load transfer ability of TiAl 3 shell layers at their interfaces, and finally attributes to significant strength enhancement (∼35% of UTS). This research provides a valuable reference concerning the size effects of addition metal in future fabrication of CNTs reinforced metal matrix composites with alternative microstructure.
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INTERNATIONAL JOURNAL OF REFRACTORY METALS & HARD MATERIALS
·
2020
·
IF 3.407
Longqing Chen,Wenbin Qiu,Hao Deng,Xiaoliang Yang,Yangyipeng Song,Jun Zhu,Jun Tang
The shrinkages presented in sintering process of tungsten alloys are extremely detrimental to their practical applications in fusion reactors. Positively in this work, we effectively reduced the shrinkages via synergistically applying Ti-doping and annealing process on tungsten‑potassium (WK) alloys. This shrinkage-fill effect only works in the one with trace amount of titanium doping, such as 0.05 wt%Ti or 0.5 wt%Ti. Due to such effect, the compressive strength was improved by ~18%. Based on morphological and elementary analyses, we speculated that the Ti-rich particles along the grain boundaries of WK alloys were activated and migrated into shrinkages during annealing. Further Ti doping (e.g. 1wt.%Ti) led to nanoscale grain refinement in WK alloys, which almost doubled the compressive strength. In this case, an unconventional grain-refinement model was proposed. Furthermore, anomalous grain growth was observed in WK-3wt.%Ti, which was attributed to the formation of Ti-rich regions and the corresponding raise of energy in grain boundaries. The fabricating strategies in this work may benefit the design of refractory tungsten alloys with less shrinkages and ultra-fine grains.
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International Journal of Applied Ceramic Technology
·
2019
·Vol. 17
·期 2
·778-789
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IF 1.074
Weihua Chen,Jiancheng Tang,Xingwang Shi,Nan Ye,Zhihao Yue,Xinghao Lin
High-purity titanium aluminum carbide (Ti 3 AlC 2 ) powders were synthesized by a microwave sintering method using different titanium sources as raw materials. The prepared products were characterized by differential scanning calorimetry (DSC), X-ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). The results indicated that the synthesized Ti 3 AlC 2 powders have high purity (97.5%) and even distribution of the grain size when using a 3TiH 2 /1.2Al/2C mixture as raw materials when the microwave sintering temperature and time were 1300°C and 30 minutes, respectively. The formation mechanism of the Ti 3 AlC 2 is described as proceeding via four stages. The solid-phase reaction between titanium and aluminum occurs below the melting point of aluminum and the main product is a Ti 3 Al phase, which is an observed intermediate compound for the formation of Ti 2 AlC and Ti 3 AlC 2 . Thus, this study provides a beneficial approach to low-temperature synthesis of high-purity Ti 3 AlC 2 materials.
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Environmental Science-Nano
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2019
·Vol. 6
·期 11
·3431-3441
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IF 7.704
Bowen Xiao,Yinqing Zhang,Xiaolei Wang,Meng Chen,Binbin Sun,Tong Zhang,Lingyan Zhu
The wide production and utilization of nanoparticulate Ag and Ti inevitably result in their release into the environment. Thus far, limited information is available regarding to what extent the nanoparticulate Ag and Ti could accumulate in biota and magnify along the food chain in real natural aquatic environments. With the application of single particle inductively coupled plasma mass spectroscopy, we quantitatively demonstrated that both nanoparticulate Ag (18.8–41.0 nm) and Ti (46.6–116 nm) occurred in the water, sediment and aquatic organisms in Taihu Lake, China. Nanoparticulate Ag exhibited greater bioaccumulation potential compared to its other chemical counterparts, and also a greater bioaccumulation factor than nanoparticulate Ti. Sediment served as a main reservoir for nanoparticulate Ag and Ti, and acted as one important exposure source for invertebrates. According to the concentrations of nanoparticulate Ag and Ti in aquatic organisms at different trophic levels, including a variety of invertebrates and fish species, the total and nanoparticulate Ti appeared to be biodiluted in the food web with trophic magnification factors (TMFs) < 1. Conversely, biomagnification of nanoparticulate Ag was found in the fish food web with a TMF of 1.21, while the total Ag was biodiluted. These findings serve as the first line of evidence on the transfer behaviors of nanoparticulate Ag and Ti along the natural aquatic food chain and underline the distinctive bioaccumulation and biomagnification behaviors of nanoparticles as opposed to their other chemical counterparts.
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JOURNAL OF POWER SOURCES
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2020
·
IF 8.247
Yangyang Luo,Chenhui Yang,Yapeng Tian,Yi Tang,Xingtian Yin,Wenxiu Que
To enhance rate and cycle performances of nickel sulfide, the two-dimensional (2D) titanium carbide (Ti 3 C 2 , MXene) with good electrical conductivity and electrochemical stability is chosen as 2D supporting matrix for synthesizing nickel sulfide/delaminated Ti 3 C 2 (Ni–S/d-Ti 3 C 2 ) nanohybrids by a solvothermal method . The Ni–S/d-Ti 3 C 2 nanohybrids show a coexistence of Ni 3 S 2 and NiS with the characteristic peak of d-Ti 3 C 2 nanosheets , and have electroactive species-on-sheet structures. The optimal Ni–S/1d-Ti 3 C 2 nanohybrid delivers a high specific capacity of 840.4 C g −1 at 1 A g −1 with enhanced capacity retention of 64.3% at 30 A g −1 and an outstanding cycle performance, which are ascribed to an integration of d-Ti 3 C 2 nanosheets that can act as electric channels to accelerate electrons transport at interface of the nanohybrid during charge-discharge processes. An increased Ni 2+ content and BET surface area also contribute to redox reactions of Ni–S/1d-Ti 3 C 2 nanohybrid electrode. An asymmetric supercapacitor (ASC) fabricated by using the Ni–S/1d-Ti 3 C 2 nanohybrid as positive electrode and d-Ti 3 C 2 film as negative electrode exhibits an energy density of 20.0 Wh kg −1 at 0.5 kW kg −1 and a good cycling stability. Our work provides a favorable ingenuity for synthesizing advanced nickel sulfide-based nanohybrids and an alternative strategy of using 2D MXene as capacitive electrode for high-performance supercapacitors .
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Materials
·
2019
·Vol. 12
·期 7
·1163
·
IF 2.972
Jiali Xue,Kuibao Zhang,Zongsheng He,Wenwen Zhao,Weiwei Li,Dayan Xie,Baozhu Luo,Kai Xu,Haibin Zhang
A rapid and effective method is necessary in the disposal of severely radioactive contaminated soil waste. Simulated Ce-bearing radioactive soil waste was immobilized by self-propagating high-temperature synthesis (SHS) within 5 min in this study. The main work includes the rapid synthesis of soil waste forms, the analysis of phase composition, microstructure and chemical durability. These results show that the simulated nuclide Ce was successfully immobilized into the pyrochlore-rich waste matrice, whose main phases are SiO2, pyrochlore (Gd2Ti2O7) and Cu. The normalized leaching rates of Si and Na on the 42nd day are 1.86 × 10−3and 1.63 × 10−2g·m−2·d−1, respectively. And the normalized leaching rate of Ce also remains at low level (10−5–10−6g·m−2·d−1) within 42 days.Keywords:Radioactive soil waste;Gd2Ti2O7pyrochlore;SHS;CeO2;Immobilization
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高影响因子
Journal of Materials Chemistry A
·
2019
·Vol. 7
·期 10
·5635-5642
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IF 10.733
Lin Yang,Yohan Dall'Agnese,Kanit Hantanasirisakul,Christopher E. Shuck,Kathleen Maleski,Mohamed Alhabeb,Gang Chen,Yu Gao,Yoshitaka Sanehira,Ajay Kumar Jena,Liang Shen,Chunxiang Dall'Agnese,Xiao-Feng Wang,Yury Gogotsi,Tsutomu Miyasaka
MXenes, a class of two-dimensional (2D) transition metal carbides and nitrides, have a wide range of potential applications due to their unique electronic, optical, plasmonic, and other properties. Herein, we explore the use of the Ti3C2 MXene in organic–inorganic lead halide perovskite solar cells (PSCs). SnO2–Ti3C2 MXene nanocomposites with different contents of Ti3C2 (0, 0.5, 1.0, 2.0, and 2.5 wt‰) were used as electron transport layers (ETLs) in low-temperature processed planar-structured PSCs. Mixing SnO2 with 1.0 wt‰ Ti3C2 effectively increases the power conversion efficiency (PCE) from 17.23% to 18.34%, whereas the device prepared with pristine Ti3C2 as the ETL achieves a PCE of 5.28%. Photoluminescence and electrochemical impedance spectroscopy results reveal that metallic Ti3C2 MXene nanosheets provide superior charge transfer paths, enhancing electron extraction, electron mobility, and decreasing the electron transfer resistance at the ETL/perovskite interface, and thus leading to higher photocurrents. This work proposes a new field of application for MXenes and a promising method to increase the efficiency of solar cells.
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APPLIED CATALYSIS B-ENVIRONMENTAL
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2019
·
IF 14.229
Zizheng Ai,Yongliang Shao,Bin Chang,Lei Zhang,Jianxing Shen,Yongzhong Wu,Baibiao Huang,Xiaopeng Hao
As a metal-free polymeric semiconductor, graphitic carbon nitride (g-C 3 N 4 ) is a promising candidate for photocatalytic water splitting but suffers from the insufficient optical absorption and sluggish utilization of photocarriers. Herein, based on the energy band engineering theory, a new design philosophy of tunable p-n homojunction is proposed and realized in a novel P-doped g-C 3 N 4 (PCN) material. Through regulating the tendency of transformation in p-n homojunction, a strong internal electric field is built and integrated with two secondary internal electric fields by further decorating with Ti 3 C 2 , leading to the formation of a triple-internal electric field system. Thus the spatial separation efficiency of photocarriers is improved and their lifetime is prolonged. The specific photocatalyst exhibits excellent overall water splitting performance in pure water with a notable quantum yield. This work presents a peculiar concept of adjustable p-n homojunction and holds great significance for the rational design of advanced photocatalyst in water splitting.
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PHYSICAL CHEMISTRY CHEMICAL PHYSICS
·
2019
·Vol. 21
·期 32
·17801-17810
·
IF 3.567
Qiushi Song,Zheng Zhang,Hongwei Xie,Huayi Yin,Zhiqiang Ning
The carbonization of transition metals in molten salts was performed to study the effect of electrochemical polarization and molten salt medium on the carbonization process. The carbonization of niobium (Nb) has been systemically investigated in Ar atmosphere and molten salts. The effect of particle size and structure of the starting materials, molten salt medium, and electric field on the formation of NbC was studied to reveal the dynamic barriers in the carbonization process. A native oxide layer and/or niobate derivatives generated on the Nb particles are the main barriers for the mass transfer of carbon and Nb towards each other. The results showed that molten salts can accelerate the formation of NbC by enhancing the diffusion of carbon, and the kinetic barrier can be effectively eliminated by supplying negative polarization to the cathode in molten salts to remove the oxide barriers, thereby enhancing carbonization. Besides Nb, tungsten (W), molybdenum (Mo), titanium (Ti), and tantalum (Ta) can also be carbonized in molten salts with the assistance of an applied electric field.
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INTERNATIONAL JOURNAL OF HYDROGEN ENERGY
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2019
·
IF 4.084
Yuan Yao,Mingxuan Sun,Zihan Zhang,Xiaojing Lin,Bowen Gao,Sambandam Anandan,Wei Liu
A ternary composites of MoO 3 /Ag/TiO 2 nanotube arrays were synthesized by in-situ annealing of TiO 2 nanotube arrays impregnated with AgNO 3 over MoO 3 powders. During the annealing process , the crystallization of the TiO 2 nanotubes, the thermo-decomposition of AgNO 3 to Ag nanoparticles , and the sublimation of MoO 3 occur jointly. The photoelectrochemical measurements of the resultants indicate that MoO 3 /Ag/TiO 2 nanotube arrays present better photoelectrochemical properties compared with Ag/TiO 2 nanotube arrays and pristine TiO 2 nanotube arrays. Especially, the highest photocurrent and open circuit voltage are up to 21.29 μA/cm 2 and 0.058 V under visible light irradiation , whereas 1.77 and 3.87 times larger than those of TiO 2 nanotube arrays, respectively. Superior photoelectrochemical stability and larger photo-conversion efficiency of the ternary composites are also demonstrated. The improved photoelectrochemical properties are related to the close interfacial contact among MoO 3 , Ag, and TiO 2 as well as the surface plasma resonance of Ag in the ternary composites, which broaden the range of light response and enhance the efficiency of charge separation. This study provides a skillful solution to construct TiO 2 -based composite materials and demonstrates it is an unique architecture to promote the visible light driven photocatalytic application of TiO 2 .
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Advanced Energy Materials
·
2019
·Vol. 9
·期 18
·1900364
·
IF 24.884
Chenyan Guo,Peng He,Rongrong Cui,Qi Shen,Nianjun Yang,Guohua Zhao
Electrochemical CO 2 reduction (ECCO 2 R) requires electrons, for example, from oxygen evolution reaction (OER). However, such a multiple-electron-involved reaction is complicated and kinetically slow, leading to high overpotential. Herein, OER is replaced with photoelectrocatalytic phenol oxidation reaction (PECPOR) that provides electrons for ECCO 2 R. In an integrated cell, ECCO 2 R is conducted on the cathode of Cu nanowires and PECPOR is performed on the anode of SnO 2 and Sb coated TiO 2 nanotubes. Significant improvement of ECCO 2 R into CO and hydrocarbons is realized when PECPOR is conducted at a high current density. The use of this integrated system results in the reduction of the specific energy consumption by a factor of 51.33%, compared with the utilization of two half-cells for individual ECCO 2 R and PECPOR. This study thus proposes a novel strategy to couple ECCO 2 R with PECPOR and eventually to tackle the problems of environmental pollution and energy crisis.
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