Tianjin, China

Tianjin University of Technology is a university in Tianjin, China under the municipal government. It is a public university approved by the State Council in 1981. As an engineering based multi-discipline university, it now has over 16,000 students, 988 teaching faculty and offers 45 Bachelor programs and 39 Master programs in areas such as science, engineering, humanities and management on 2 campuses. Wikipedia.

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Zhang P.,Tianjin University of Technology | Zhang J.,Tianjin University of Technology | Gong J.,Tianjin University of Technology
Chemical Society Reviews | Year: 2014

Solar energy utilization is one of the most promising solutions for the energy crises. Among all the possible means to make use of solar energy, solar water splitting is remarkable since it can accomplish the conversion of solar energy into chemical energy. The produced hydrogen is clean and sustainable which could be used in various areas. For the past decades, numerous efforts have been put into this research area with many important achievements. Improving the overall efficiency and stability of semiconductor photocatalysts are the research focuses for the solar water splitting. Tantalum-based semiconductors, including tantalum oxide, tantalate and tantalum (oxy)nitride, are among the most important photocatalysts. Tantalum oxide has the band gap energy that is suitable for the overall solar water splitting. The more negative conduction band minimum of tantalum oxide provides photogenerated electrons with higher potential for the hydrogen generation reaction. Tantalates, with tunable compositions, show high activities owning to their layered perovskite structure. (Oxy)nitrides, especially TaON and Ta3N5, have small band gaps to respond to visible-light, whereas they can still realize overall solar water splitting with the proper positions of conduction band minimum and valence band maximum. This review describes recent progress regarding the improvement of photocatalytic activities of tantalum-based semiconductors. Basic concepts and principles of solar water splitting will be discussed in the introduction section, followed by the three main categories regarding to the different types of tantalum-based semiconductors. In each category, synthetic methodologies, influencing factors on the photocatalytic activities, strategies to enhance the efficiencies of photocatalysts and morphology control of tantalum-based materials will be discussed in detail. Future directions to further explore the research area of tantalum-based semiconductors for solar water splitting are also discussed. © 2014 The Royal Society of Chemistry.

Li S.,Tianjin University of Technology | Gong J.,Tianjin University of Technology
Chemical Society Reviews | Year: 2014

Owing to the considerable publicity that has been given to petroleum related economic, environmental, and political problems, renewed attention has been focused on the development of highly efficient and stable catalytic materials for the production of chemical/fuel from renewable resources. Supported nickel nanoclusters are widely used for catalytic reforming reactions, which are key processes for generating synthetic gas and/or hydrogen. New challenges were brought out by the extension of feedstock from hydrocarbons to oxygenates derivable from biomass, which could minimize the environmental impact of carbonaceous fuels and allow a smooth transition from fossil fuels to a sustainable energy economy. This tutorial review describes the recent efforts made toward the development of nickel-based catalysts for the production of hydrogen from oxygenated hydrocarbons via steam reforming reactions. In general, three challenges facing the design of Ni catalysts should be addressed. Nickel nanoclusters are apt to sinter under catalytic reforming conditions of high temperatures and in the presence of steam. Severe carbon deposition could also be observed on the catalyst if the surface carbon species adsorbed on metal surface are not removed in time. Additionally, the production of hydrogen rich gas with a low concentration of CO is a challenge using nickel catalysts, which are not so active in the water gas shift reaction. Accordingly, three strategies were presented to address these challenges. First, the methodologies for the preparation of highly dispersed nickel catalysts with strong metal-support interaction were discussed. A second approach - the promotion in the mobility of the surface oxygen - is favored for the yield of desired products while promoting the removal of surface carbon deposition. Finally, the process intensification via the in situ absorption of CO2 could produce a hydrogen rich gas with low CO concentration. These approaches could also guide the design of other types of heterogeneous base-metal catalysts for high temperature processes including methanation, dry reforming, and hydrocarbon combustion. © 2014 the Partner Organisations.

Zhao N.,Tianjin University of Technology
Nature Photonics | Year: 2015

Increasing the information capacity per unit bandwidth has been a perennial goal of scientists and engineers. Multiplexing of independent degrees of freedom, such as wavelength, polarization and more recently space, has been a preferred method to increase capacity in both radiofrequency and optical communication. Orbital angular momentum, a physical property of electromagnetic waves discovered recently, has been proposed as a new degree of freedom for multiplexing to achieve capacity beyond conventional multiplexing techniques, and has generated widespread and significant interest in the scientific community. However, the capacity of orbital angular momentum multiplexing has not been established or compared to other multiplexing techniques. Here, we show that orbital angular momentum multiplexing is not an optimal technique for realizing the capacity limits of a free-space communication channel and is outperformed by both conventional line-of-sight multi-input multi-output transmission and spatial-mode multiplexing. © 2015 Nature Publishing Group

Yue H.,Tianjin University of Technology | Ma X.,Tianjin University of Technology | Gong J.,Tianjin University of Technology
Accounts of Chemical Research | Year: 2014

ConspectusEthanol is an attractive end product and a versatile feedstock because a widespread market exists for its commercial use as a fuel additive or a potential substitute for gasoline. Currently, ethanol is produced primarily by fermentation of biomass-derived sugars, particularly those containing six carbons, but coproducts 5-carbon sugars and lignin remain unusable. Another major process for commercial production of ethanol is hydration of ethylene over solid acidic catalysts, yet not sustainable considering the depletion of fossil fuels. Catalytic conversion of synthetic gas (CO + H2) could produce ethanol in large quantities. However, the direct catalytic conversion of synthetic gas to ethanol remains challenging, and no commercial process exists as of today although the research has been ongoing for the past 90 years, since such the process suffers from low yield and poor selectivity due to slow kinetics of the initial C-C bond formation and fast chain growth of the C 2 intermediates.This Account describes recent developments in an alternative approach for the synthesis of ethanol via synthetic gas. This process is an integrated technology consisting of the coupling of CO with methanol to form dimethyl oxalate and the subsequent hydrogenation to yield ethanol. The byproduct of the second step (methanol) can be separated and used in circulation as the feedstock for the coupling step. The coupling reaction of carbon monoxide for producing dimethyl oxalate takes place under moderate reaction conditions with high selectivity (∼95%), which ideally leads to a self-closing, nonwaste, catalytic cycling process. This Account also summarizes the progress on the development of copper-based catalysts for the hydrogenation reaction with remarkable efficiencies and stability. The unique lamellar structure and the cooperative effect between surface Cu0 and Cu + species are responsible for the activity of the catalyst with high yield of ethanol (∼91%). The understanding of nature of valence states of Cu could also guide the rational design of Cu-based catalysts for other similar reactions, particularly for hydrogenation catalytic systems. In addition, by regulating the reaction condition and the surface structure of the catalysts, the products in the hydrogenation steps, such as ethanol, methyl glycolate, and ethylene glycol, could be tuned efficiently. This synthetic approach enables a more sustainable ethanol, methyl glycolate, and ethylene glycol synthesis in industry and greatly reduces the dependence on petroleum resources and the emission of the greenhouse gas. © 2014 American Chemical Society.

Yue H.,Tianjin University of Technology | Zhao Y.,Tianjin University of Technology | Ma X.,Tianjin University of Technology | Gong J.,Tianjin University of Technology
Chemical Society Reviews | Year: 2012

Ethylene glycol (EG) is an important organic compound and chemical intermediate used in a large number of industrial processes (e.g. energy, plastics, automobiles, and chemicals). Indeed, owing to its unique properties and versatile commercial applications, a variety of chemical systems (e.g., catalytic and non-catalytic) have been explored for the synthesis of EG, particularly via reaction processes derived from fossil fuels (e.g., petroleum, natural gas, and coal) and biomass-based resources. This critical review describes a broad spectrum of properties of EG and significant advances in the prevalent synthesis and applications of EG, with emphases on the catalytic reactivity and reaction mechanisms of the main synthetic methodologies and applied strategies. We also provide an overview regarding the challenges and opportunities for future research associated with EG. This journal is © The Royal Society of Chemistry.

Gong J.,Tianjin University of Technology
Chemical Reviews | Year: 2012

A study was conducted to investigate structure and surface chemistry of gold-based model catalysts. The study started with an overview of surface structures and electronic properties of various gold (Au) single-crystal surfaces. It examined adsorption phenomena on Au macroscopic crystalline surfaces under the investigations. Investigations revealed that gold crystallized as a face-centered cubic (fcc) structure where three low Miller indexed surfaces, such as 100, 110, and 111 were considered. The 111 facet of gold had the lowest surface energy among other surfaces, as reflected in the growing tendency for thin film in the [111] direction. It had the highest ductility and malleability of any element, and was the only metal for which the close-packed surface of an fcc crystal had been observed to reconstruct, which was attributed to relativistic effects in the large electronic core of gold.

Wang W.,Tianjin University of Technology | Wang S.,Tianjin University of Technology | Ma X.,Tianjin University of Technology | Gong J.,Tianjin University of Technology
Chemical Society Reviews | Year: 2011

Owing to the increasing emissions of carbon dioxide (CO2), human life and the ecological environment have been affected by global warming and climate changes. To mitigate the concentration of CO2 in the atmosphere various strategies have been implemented such as separation, storage, and utilization of CO2. Although it has been explored for many years, hydrogenation reaction, an important representative among chemical conversions of CO2, offers challenging opportunities for sustainable development in energy and the environment. Indeed, the hydrogenation of CO 2 not only reduces the increasing CO2 buildup but also produces fuels and chemicals. In this critical review we discuss recent developments in this area, with emphases on catalytic reactivity, reactor innovation, and reaction mechanism. We also provide an overview regarding the challenges and opportunities for future research in the field (319 references). © 2011 The Royal Society of Chemistry.

Liang M.,Tianjin University of Technology | Liang M.,Nankai University | Chen J.,Nankai University
Chemical Society Reviews | Year: 2013

Arylamine organic dyes with donor (D), π-bridge (π) and acceptor (A) moieties for dye-sensitized solar cells (DSCs) have received great attention in the last decade because of their high molar absorption coefficient, low cost and structural variety. In the early stages, the efficiency of DSCs with arylamine organic dyes with D-π-A character was far behind that of DSCs with ruthenium(ii) complexes partly due to the lack of information about the relationship between the chemical structures and the photovoltaic performance. However, exciting progress has been recently made, and power conversion efficiencies over 10% were obtained for DSCs with arylamine organic dyes. It is thus that the recent research and development in the field of arylamine organic dyes employing an iodide/triiodide redox couple or polypyridyl cobalt redox shuttles as the electrolytes for either DSCs or solid-state DSCs has been summarized. The cell performance of the arylamine organic dyes are compared, providing a comprehensive overview of arylamine organic dyes, demonstrating the advantages/disadvantages of each class, and pointing out the field that needs to reinforce the research direction in the further application of DSCs. © 2013 The Royal Society of Chemistry.

Xiao S.,Macau University of Science and Technology | Li Y.,Tianjin University of Technology
IEEE Transactions on Industrial Electronics | Year: 2013

This paper presents the optimal design, fabrication, and control of a novel compliant flexure-based totally decoupled XY micropositioning stage driven by electromagnetic actuators. The stage is constructed with a simple structure by employing double four-bar parallelogram flexures and four noncontact types of electromagnetic actuators to realize the kinematic decoupling and force decoupling, respectively. The kinematics and dynamics modeling of the stage are conducted by resorting to compliance and stiffness analysis based on matrix method, and the parameters are obtained by multiobjective genetic algorithm (GA) optimization method. The analytical models for electromagnetic forces are also established, and both mechanical structure and electromagnetic models are validated by finite-element analysis via ANSYS software. It is found that the system is with hysteresis and nonlinear characteristics when a preliminary open-loop test is conducted; thereafter, a simple PID controller is applied. Therefore, an inverse Preisach model-based feedforward sliding-mode controller is exploited to control the micromanipulator system. Experiments show that the moving range can achieve 1 mm × 1 mm and the resolution can reach ± 0.4μm. Moreover, the designed micromanipulator can bear a heavy load because of its optimal mechanical structure. © 1982-2012 IEEE.

Tang S.,Tianjin University of Technology | Baker G.A.,University of Missouri | Zhao H.,Savannah State University
Chemical Society Reviews | Year: 2012

In recent years, the designer nature of ionic liquids (ILs) has driven their exploration and exploitation in countless fields among the physical and chemical sciences. A fair measure of the tremendous attention placed on these fluids has been attributed to their inherent designer nature. And yet, there are relatively few examples of reviews that emphasize this vital aspect in an exhaustive or meaningful way. In this critical review, we systematically survey the physicochemical properties of the collective library of ether- and alcohol-functionalized ILs, highlighting the impact of ionic structure on features such as viscosity, phase behavior/transitions, density, thermostability, electrochemical properties, and polarity (e.g. hydrophilicity, hydrogen bonding capability). In the latter portions of this review, we emphasize the attractive applications of these functionalized ILs across a range of disciplines, including their use as electrolytes or functional fluids for electrochemistry, extractions, biphasic systems, gas separations, carbon capture, carbohydrate dissolution (particularly, the (ligno)celluloses), polymer chemistry, antimicrobial and antielectrostatic agents, organic synthesis, biomolecular stabilization and activation, and nanoscience. Finally, this review discusses anion-functionalized ILs, including sulfur- and oxygen-functionalized analogs, as well as choline-based deep eutectic solvents (DESs), an emerging class of fluids which can be sensibly categorized as semi-molecular cousins to the IL. Finally, the toxicity and biodegradability of ether- and alcohol-functionalized ILs are discussed and cautiously evaluated in light of recent reports. By carefully summarizing literature examples on the properties and applications of oxy-functional designer ILs up till now, it is our intent that this review offers a barometer for gauging future advances in the field as well as a trigger to spur further contemplation of these seemingly inexhaustible and - relative to their potential - virtually untouched fluids. It is abundantly clear that these remarkable fluidic materials are here to stay, just as certain design rules are slowly beginning to emerge. However, in fairness, serendipity also still plays an undeniable role, highlighting the need for both expanded in silico studies and a beacon to attract bright, young researchers to the field (406 references). © 2012 The Royal Society of Chemistry.

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