查找使用阿拉丁产品的科研文献

Improving Active Ti Contents in TS-1 by Controlling the Alkalinity and Crystallization Rate

Jiaojiao Yu,Yi Zuo,Gudan Li,Hong Yang,Xinwen Guo

To synthesize a high-performance titanium silicalite-1 (TS-1), this paper reports a simple and environmentally friendly approach to regulate the alkalinity in the synthesis of titanium silicalite-1 (TS-1) involving tetrapropylammonium hydroxide (TPAOH) and tetrapropylammonium bromide (TPABr). Essentially, the pH of the synthesis gel was controlled by n(TPAOH/TPA+), while keeping the total tetrapropylammonium cations (TPA+) constant. The study shows that at a relatively moderate alkalinity of pH = 10.7, TS-1 produced exhibits nanocrystalline microstructure favorable for diffusion, contains high contents of TiO4 and TiV, and delivers 94.3% of H2O2 conversion with a turnover frequency of 565.6 mol (mol h)−1 in propylene epoxidation. Through detailed analysis of crystallization processes of TS-1 at different alkalinities, this study unveils the effect of alkalinity on the rate of Si–Ti condensation, which dictates the formation of the framework structure and incorporation of Ti species into the framework. Essentially, only at moderate alkalinity of pH = 10.7, comparable Si–OH and Ti–OH condensation rates permit the highest amount of Ti being inserted in TS-1 as active (TiO4 + TiV) and limits the self-condensation of Ti species to form inactive anatase-TiO2.

Pd1-O-Ti dual sites for efficient electrochemical active hydrogen generation and bromate reduction

Wei Hou,Qian Zheng,Hengyue Xu,Guangming Zhan,Long Zhao,Jie Dai,Jiaxian Wang,Xingyue Zou,Bing Zhou,Lufa Hu,Ruizhao Wang,Kaiyuan Wang,Yancai Yao,Lizhi Zhang

Atomic hydrogen (H*) plays a crucial role in electrochemical reduction technology towards various environmental and energy applications, but suffers from low utilization efficiency arisen from the undesirable H–H dimerization and the competitive adsorption between water molecule with reactants on the traditional adjacent catalytic sites. Herein, we anchored Pd single atoms on the naturally formed titanium oxide of titanium foam to construct Pd 1 -O-Ti dual-site electrocatalyst with spatially isolated water dissociation and H* utilization site, which synchronously inhibits the H–H dimerization and the competitive adsorption of water molecule and targeted reactants. Experiments and theoretical calculations revealed that the Ti–O sites could synergistically dissociate water to H*, which overflowed to nearby Pd single-atom sites for designed reduction reactions and utilization benefiting from the hydrogen spillover ability of titanium oxide substrate. These Pd 1 -O-Ti dual sites delivered almost 100 % bromate reduction efficiency with a rate constant of 1.57 h –1 , far superior to those of Pd n -O-Ti with adjacent Pd sites (0.52 h –1 ), Pd 1 -N-C with single sites (0.04 h –1 ) and commercial Pd/C (0.18 h –1 ), respectively. This study sheds light on the importance of integrating synergistic active sites for complicated electrochemical reactions, and provide new insights in improving H* utilization for environmental remediation.

PVDF-based energetic films with high output performance: Synergistic effect based on Al/Ti

Lejian Chen,Xianghong Xiao,Haofang Yuan,Hongyu Chen,Yuxuan Zhou,Yinghua Ye,RuiQi Shen,Lizhi Wu

With the ongoing advancement of miniaturization and microfabrication, Micro-Electro-Mechanical Systems (MEMS) energetic devices are increasingly demanding higher output capabilities from energetic materials. This study investigates the incorporation of Titanium (Ti) into PVDF-based energetic films to improve their performance. We fabricated five Al/Ti/CuO/PVDF energetic composite films with varying Ti contents by direct ink writing (DIW). The results indicate that the Al/Ti/CuO/PVDF films demonstrate superior performance compared to Al/CuO/PVDF(AT-0). Notably, the 50 wt% Al/50 wt% Ti/CuO/PVDF (AT-50) film achieved optimal performance, exhibiting a 68% increase in combustion rate compared to the AT-0 film. Additionally, it showed a reduction in ignition delay time by 6 ms, an increase in flame temperature of 160.9 K, a 24% rise in maximum pressure, a pressurization rate enhancement of 117%, and an overall increase in heat release of 26.8%. This is attributed to the synergistic effect of the Al/Ti bimetallic fuels, where their close contact creates an alloying reaction that releases a large amount of heat and avoids the detrimental effects of Al sintering. This Al/Ti/CuO/PVDF energetic composite film, characterized by its exceptional synergistic mechanism and high energy output, holds significant promise for integration with MEMS devices, paving the way for innovative applications in micro-ignition, micro-propulsion, and micro-startup technologies. Highlights Ti was added to the PVDF-based energetic films to form the dual-fuel system. The Al/Ti dual-fuel has a synergistic effect to improve output performance. The 50wt%Al/50wt%Ti/CuO/PVDF film can achieve optimal output performance.

Transforming monolayer Ti₃C₂Tx MXene into potassium titanate for room-temperature NO₂ sensing

Zhaorui Zhang,Haiying Du,Huashuai Hu,Dongchen Tan,Jinkui Chu,Minghui Yang

Two-dimensional transition metal carbon nitrides (MXenes) are a prominent class of functional materials with significant potential for sensing applications. However, their conventional charge transfer mechanisms pose limitations for detecting nitrogen dioxide (NO 2 ). In this study, we successfully design-synthesized potassium titanate (KTO) nanoribbons by oxidizing and alkalizing monolayer Ti 3 C 2 T x MXene, targeting room-temperature NO 2 detection. The Ti 3 C 2 T x -derived KTO exhibited exceptional selectivity for NO 2 , achieving a remarkable response of 649.2 % for 50 ppm NO 2 , which is 550 times higher than that of the Ti 3 C 2 T x sensor (1.18 %). Additionally, the sensor demonstrated a detection limit as low as 5 ppb at room temperature, along with rapid response (1 s) and recovery times (2 s), and excellent linearity. Computational analysis showed that the abundant OH groups on the KTO surface contribute to strong selective adsorption (2.79 |eV|) and efficient electron transfer (0.91 |e|) for NO 2 . The unique proton conduction mechanism of KTO further reduced the activation energy for proton transport, enhancing NO 2 sensing performance. This study highlights the potential of Ti 3 C 2 T x -derived KTO nanomaterials for advanced room-temperature NO 2 detection and sensor technology development.

Non-Bonded Interaction Driven Morphology Evolution of CuMOF@MXene Energetic Composites: Synergistic Optimization of Thermal Stability and Combustion Performance

Ke-Juan Meng,Xinwen Ma,Kunyu Xiong,Xiaoxia Ma,Iftikhar Hussain,Momang Tian,Kaili Zhang

Hybrid materials with tunable properties, particularly metal-organic frameworks (MOFs)@MXene composites have emerged as a cutting-edge research focus different applications. In this study, a novel energetic CuMOF composed of Cu 2+ and 3-(tetrazol-5-yl) triazole is synthesized, followed by the development of CuMOF@MXene composites (CuMOF@MX x ) via a facile one-step hydrothermal method. This approach leverages the interfacial “Ti─O···Cu” non-bonded interactions to achieve composites with diverse morphologies. Subsequently, both experiments and theoretical calculations verify the presence of these non-bonded interactions and their influence on morphology, thermal property, and combustion performance of the composites. The morphologies of composites transition from a flower-like structure to a spherical shape with the addition of Ti 3 C 2 T x MXene. Furthermore, simultaneous thermogravimetry-differential scanning calorimetry tests, along with non-isothermal kinetic analysis, indicate that CuMOF@MX 4 has a higher initial temperature of 354.2 °C for runaway reaction and a larger activation energy of 211.58 kJ mol −1 , compared to CuMOF (314.9 °C and 202.56 kJ mol −1 ). In addition, the combustion tests demonstrate that CuMOF@MX x exhibit more intense and rapid combustion. This work demonstrates the critical role of the non-bonded interaction between CuMOF and Ti 3 C 2 T x interfaces in regulating the structure and properties of the composites, and the possible mechanism of this process is also elucidated.

Active Site Regulation on Mo/Ti Catalysts for the Direct Dehydrogenation of Fluoroalkanes to Fluoroalkenes

Wucan Liu,Junxing Wang,Xiang Sun,Ming Cheng,Jiamin Jin,Dang-Guo Cheng,Fengqiu Chen

Vinylidene fluoride (VDF) is a fundamental fluorinated olefin in the fluorochemical industry, and innovation in its production holds significant importance for sustainable development. Traditional routes involving the dehydrohalogenation or dehalogenation of halogenated alkanes suffer from issues such as substantial waste emissions and severe equipment corrosion. The one-step catalytic dehydrogenation of 1,1-difluoroethane (HFC-152a) to produce VDF offers notable advantages. To accomplish this goal, this work innovatively aims to construct an oxidative dehydrogenation system with a highly dispersed Mo/Ti catalyst for HFC-152a. Through systematic characterization techniques, such as XPS, XRD, Raman spectroscopy, and TPD, the reaction mechanism is thoroughly investigated. These results prove that more abundant O2– species are related to improved activity, achieving 21.1% VDF selectivity and modest stability for at least 20 h.

Highly Sensitive Surface Plasmon Resonance Sensor Modified With 2D Ti₂C MXene for Solution Detection

Shuaiwen Gan,Banxian Ruan,Yuanjiang Xiang,Xiaoyu Dai

Pd-Ni/Cd loaded PPy/Ti composite electrode: Synthesis, characterization, and application for hydrogen storage

Xiaoyang Wan,Xuefeng Wei,Juan Miao,Ruichang Zhang,Jun Zhang,Qingshan Jason Niu

Summary A wide compositional range of Pd-Ni/Cd on polypyrrole (PPy)-modified Ti plates (Pd-Ni/Cd/PPy/Ti) was fabricated via electrochemical deposition. The hydrogen absorption properties of the prepared Pd-Ni/Cd/PPy/Ti electrodes were evaluated using cyclic voltammetry and chronoamperometry in acidic media. The optimal Pd 36 -Ni 7 /Cd 57 /PPy/Ti electrode achieved a hydrogen storage capacity of 331.3 mC cm −2 mg −1 and an H/Pd ratio of 0.77. The enhancement of the hydrogen storage was attributed to a synergistic effect between the Pd-Ni/Cd catalysts. The surface morphology, crystallinity, and chemical composition of the Pd-Ni/Cd/PPy/Ti electrode were characterized using scanning electron microscope (SEM), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS), respectively. Hydrogen spillover occurred on the trimetallic catalysts, and secondary hydrogen spillover occurred on the PPy/Ti support. The enhanced hydrogen sorption capacity was due to both the synergistic effect of the trimetallic catalysts and the assistance of PPy, making Pd-Ni/Cd/PPy/Ti a promising hydrogen storage material.

Preparation of NCh-B and NCh-B-Ti nanocomposites and their ignition and combustion performances

Yu-shu Xiong,Yong-qi Wang,Chong Wan,Wen-zhen Zhang,Zhao Qin,Su-hang Chen,Kang-zhen Xu

To overcome the agglomeration and insufficient combustion of nano-boron (n-B) powders, this study successfully prepared two novel types of boron-based nanocomposites using the acoustic resonance technology, namely high-substitute nitrochitosan/nano-boron (NCh-B) with ratios of 1:3, 1:5, 1:7 and 1:9, and nitrochitosan/nano-boron powder/nano-titanium (NCh-B-Ti) with Ti contents of 5 wt%, 10 wt%, 15 wt% and 20 wt%. The structural morphologies, laser ignition and combustion properties of the composites were systematically investigated. The results suggest that the addition of NCh can significantly improve the dispersion of n-B. NCh-B exhibited a higher combustion performance than n-B, as evidenced by their ignition delay and flame areas. When the laser power density was 81 W, NCh-B 5 -Ti 15% exhibited a combustion time and an ignition delay of 240 ms and 5.5 ms respectively, which were higher and lower than those of NCh-B 5 (199 ms and 17 ms, respectively). Furthermore, NCh-B 5 -Ti 15% displayed a lower ignition delay than both n-B powders (12 ms) and NCh-B (11 ms), as well as brighter flames and a larger combustion area. Therefore, the addition of n-Ti can promote the combustion of n-B powders, with the combustion products of NCh-B-Ti including H 3 BO 3 , B 2 O 3 , TiB 2 , and TiO. This study provides a new method for improving the ignition performance and combustion efficiency of n-B powders.

Electron impact excitation of allowed and forbidden transitions between fine-structure levels in Ti III

Yang Wang,Qiuyao Cao,Xi-Ming Zhu,Chun-Meng Du,Klaus Bartschat

Abstract. Introduction: We present an extensive theoretical investigation of the electron impact excitation of doubly-ionized titanium (Ti III) to meet the needs of spectral analysis and plasma modeling. OBJECTIVES: The main objective of this work is to extend the currently scarce database of both structure and collision data for Ti III. METHODS: The calculation was performed in the close-coupling approximation using the B-spline R-matrix method. The multi-configuration Hartree–Fock method in combination with B-spline configuration interaction expansions and the non-orthogonal orbitals technique is employed for accurate descriptions of the target wave functions and adequate accounts of the various interactions between the target states. Relativistic effects are treated at the semi-relativistic Breit-Pauli approximation level. RESULTS: The present close-coupling expansion includes 138 fine-structure levels of Ti III belonging to the 3d2, 4s2, 4s4p, 3d4l (l=0-3), 3d5l (l=0-3), 3d6s, and 3d6p configurations. Comprehensive sets of radiative and electron collisional data are reported for all of the possible transitions between the 138 fine-structure levels. Thermally averaged collision strengths are determined using a Maxwellian distribution for a wide range of temperatures from 102 K to 105 K. The accuracy of the calculated radiative parameters is validated by comparing with available values from the NIST database and previous literature. CONCLUSION: Given the lack of sufficient currently available experimental and theoretical data, the electron impact excitation cross sections of the Ti III fine-structure levels presented here are systematic, extensive, and internally consistent, thus making them suitable for many modeling applications.

Fabrication of highly dispersed Ti/ZnO–Cr2O3 composite as highly efficient photocatalyst for naphthalene degradation

Shengjie Xia,Lianyang Zhang,Xiaobo Zhou,Mengmeng Shao,Guoxiang Pan,Zheming Ni

In this paper, Ti-contained Schiff base complex was intercalated into the interlayer of the ZnCr layered double hydroxides (LDHs) to form a novel layered organic–inorganic nanoscale material. And then, the hybrid material was further calcined to make metal oxides composite contained Zn, Cr and Ti (Ti/ZnO–Cr 2 O 3 ). This composite was used to study the performance and mechanism for naphthalene ( l -acid) photodegradation under visible light. The characterization results showed that Ti/ZnO–Cr 2 O 3 composite has higher specific area, more uniform pores size distribution and narrower band gap than that of original ZnCr–LDHs. Both physico-chemical property and photocatalytic performance for l -acid degradation by Ti/ZnO–Cr 2 O 3 were greatly improved with the increasing of calcination temperature, due to the highly crystalline structures with appearance of spinel ingredients of Zn, Cr and Ti. In addition, the molar ratio of Ti/Cr would also influence the photocatalytic property of the materials. Ti/ZnO–Cr 2 O 3 composite with Ti/Cr   =   1 and calcined at 800   °C not only has narrow bang gap (2.11   eV) and high surface area (227   m 2 ), but also shows highest photocatalytic performance for l -acid degradation (90.2% within 240   min). Furthermore, the types and amounts of active radicals of photo oxidation reaction were also tested. The photocatalytic mechanism of the Ti/ZnO–Cr 2 O 3 composite was also discussed. Moreover, based on the results from HPLC–MS, GC–MS, FT–IT and DFT analysis, the decomposition intermediates and reaction pathway for l -acid were investigated in detail.

Biofunctionalization of carbon nanotubes/chitosan hybrids on Ti implants by atom layer deposited ZnO nanostructures

Yizhou Zhu,Xiangmei Liu,Kelvin W.K. Yeung,Paul K. Chu,Shuilin Wu

One-dimensional (1D) nanostructures of ZnO using atomic layer deposition (ALD) on chitosan (CS) modified carbon nanotubes (CNTs) were first introduced onto the surfaces of biomedical implants. When the content of ZnO is not sufficient, CNTs can strengthen the antibacterial activity against E. coli and S. aureus by 8% and 39%, respectively. CS can improve the cytocompatibility of CNTs and ZnO. The amount of Zn content can be controlled by changing the cycling numbers of ALD processes. This hybrid coating can not only endow medical implants with high self-antibacterial efficacy against Escherichia coli ( E. coli ) and Staphylococcus aureus ( S. aureus ) of over 73% and 98%, respectively, but also regulate the proliferation and osteogenic differentiation of osteoblasts by controlling the amount of ZnO.