Tianmo Liu

Bio: Tianmo Liu is an academic researcher from Chongqing University. The author has contributed to research in topics: Crystal twinning & Hydrothermal synthesis. The author has an hindex of 32, co-authored 136 publications receiving 3287 citations. Previous affiliations of Tianmo Liu include Tohoku University.

Enhanced gas sensing properties by SnO2 nanosphere functionalized TiO2 nanobelts

Abstract: We report synthesis of hierarchical nanostructures of SnO2 nanosphere functionalized TiO2 nanobelts as a novel sensing material by a simple hydrothermal technique. A systematic comparison study reveals an enhanced gas sensing performance for the sensor made of SnO2 and TiO2 toward volatile organic compounds of several species over that of the commonly applied undecorated TiO2 nanobelts. The improved gas sensing properties are attributed to the pronounced electron transfer between the hierarchical nanostructures and the absorbed oxygen species as well as to the heterojunctions of the SnO2 nanospheres to the TiO2 nanobelts which provide additional reaction rooms. The results represent an advance of hierarchical nanostructures in further enhancing the functionality of gas sensors, and this facile method could be applicable to many sensing materials.

Gas-sensing performance enhancement in ZnO nanostructures by hierarchical morphology

Abstract: We report a successful synthesis of ZnO nanoparticles, nanosheets and nanoflowers via a simple hydrothermal process, and investigate comprehensively their gas-sensing performances. Of all the nanostructures, nanoflowers are found to show the most superior gas-sensing properties, e.g., highest gas response, shortest response and recovery time, excellent selectivity, and good repeatability and stability, which are attributed to their unique three-dimensional hierarchical structures with the largest specific surface area arising from remarkable amount of petals and pores. Further, the sodium citrate is found to be the key to producing such unique flower-like architecture, which can be understood upon the nucleation and self-assembly of building blocks of ZnO. Such development of the hierarchical architectures may open up an avenue to further enhance the gas-sensing performances of ZnO nanostructures for the on-site detection of the gases of interest.

Selective Detection of Formaldehyde Gas Using a Cd-Doped TiO(2)-SnO(2) Sensor.

Abstract: We report the microstructure and gas-sensing properties of a nonequilibrium TiO2-SnO2 solid solution prepared by the sol-gel method. In particular, we focus on the effect of Cd doping on the sensing behavior of the TiO2-SnO2 sensor. Of all volatile organic compound gases examined, the sensor with Cd doping exhibits exclusive selectivity as well as high sensitivity to formaldehyde, a main harmful indoor gas. The key gas-sensing quantities, maximum sensitivity, optimal working temperature, and response and recovery time, are found to meet the basic industrial needs. This makes the Cd-doped TiO2-SnO2 composite a promising sensor material for detecting the formaldehyde gas.

Hydrogen sensing and mechanism of M-doped SnO2 (M = Cr3+, Cu2+ and Pd2+) nanocomposite

Abstract: The microstructure of M-doped SnO2 (M = Cr3+, Cu2+ and Pd2+) prepared by the sol–gel method and their gas-sensing performance were investigated. In particular, we focus on the effects of metallic ions on the hydrogen sensing behavior of the SnO2-based sensor. It is found that hydrogen gas response of SnO2 can be enhanced evidently by adding Pd2+, while such effect from Cr3+ and Cu2+ exhibits somewhat slight. A theoretical study based on first principles calculation shows that SnO2–Pd (1 1 0) surface enable adsorb more H2 gas and receive larger electrons from adsorbed H2 molecule, thereby holding the potential for the improvement of gas response to hydrogen.

Selective Detection of Formaldehyde Gas Using a Cd-Doped

Abstract: We report the microstructure and gas-sensing properties of a nonequilibrium TiO2-SnO2 solid solution prepared by the sol-gel method. In particular, we focus on the effect of Cd doping on the sensing behavior of the TiO2-SnO2 sensor. Of all volatile organic compound gases examined, the sensor with Cd doping exhibits exclusive selectivity as well as high sensitivity to formaldehyde, a main harmful indoor gas. The key gas-sensing quantities, maximum sensitivity, optimal working temperature, and response and recovery time, are found to meet the basic industrial needs. This makes the Cd-doped TiO2-SnO2 composite a promising sensor material for detecting the formaldehyde gas.

I and i

Abstract: There is, I think, something ethereal about i —the square root of minus one. I remember first hearing about it at school. It seemed an odd beast at that time—an intruder hovering on the edge of reality. Usually familiarity dulls this sense of the bizarre, but in the case of i it was the reverse: over the years the sense of its surreal nature intensified. It seemed that it was impossible to write mathematics that described the real world in …

반도체 공정 overview

Abstract: With digital equipment becoming increasingly networked, either on wired or wireless networks, for personal and professional use alike, distributed software systems have become a crucial element in information and communications technologies. The study of these systems forms the core of the ARLES' work, which is specifically concerned with defining new system software architectures, based on the use of emerging networking technologies. In this context, we concentrate on the study of distributed systems which bring to life the vision of ubiquitous computing systems, also known as ambient intelligence.

Nanoscale metal oxide-based heterojunctions for gas sensing: A review

Abstract: Metal oxide-based resistive-type gas sensors are solid-state devices which are widely used in a number of applications from health and safety to energy efficiency and emission control. Nanomaterials such as nanowires, nanorods, and nanoparticles have dominated the research focus in this field due to their large number of surface sites facilitating surface reactions. Previous studies have shown that incorporating two or more metal oxides to form a heterojunction interface can have drastic effects on gas sensor performance, especially the selectivity. Recently, these effects have been amplified by designing heterojunctions on the nano-scale. These designs have evolved from mixed commercial powders and bi-layer films to finely-tuned core–shell and hierarchical brush-like nanocomposites. This review details the various morphological classes currently available for nanostructured metal-oxide based heterojunctions and then presents the dominant electronic and chemical mechanisms that influence the performance of these materials as resistive-type gas sensors. Mechanisms explored include p–n and n–n potential barrier manipulation, n–p–n response type inversions, spill-over effects, synergistic catalytic behavior, and microstructure enhancement. Tables are presented summarizing these works specifically for SnO2, ZnO, TiO2, In2O3, Fe2O3, MoO3, Co3O4, and CdO-based nanocomposites. Recent developments are highlighted and likely future trends are explored.

Polyvinylpyrrolidone (PVP) in nanoparticle synthesis

Abstract: Colloidal synthesis offers a route to nanoparticles (NPs) with controlled composition and structural features. This Perspective describes the use of polyvinylpyrrolidone (PVP) to obtain such nanostructures. PVP can serve as a surface stabilizer, growth modifier, nanoparticle dispersant, and reducing agent. As shown with examples, its role depends on the synthetic conditions. This dependence arises from the amphiphilic nature of PVP along with the molecular weight of the selected PVP. These characteristics can affect nanoparticle growth and morphology by providing solubility in diverse solvents, selective surface stabilization, and even access to kinetically controlled growth conditions. This Perspective includes discussions of the properties of PVP-capped NPs for surface enhanced Raman spectroscopy (SERS), assembly, catalysis, and more. The contribution of PVP to these properties as well as its removal is considered. Ultimately, the NPs accessed through the use of PVP in colloidal syntheses are opening new applications, and the concluding guidelines provided herein should enable new nanostructures to be accessed facilely.

A Survey on Gas Sensing Technology

Abstract: Sensing technology has been widely investigated and utilized for gas detection. Due to the different applicability and inherent limitations of different gas sensing technologies, researchers have been working on different scenarios with enhanced gas sensor calibration. This paper reviews the descriptions, evaluation, comparison and recent developments in existing gas sensing technologies. A classification of sensing technologies is given, based on the variation of electrical and other properties. Detailed introduction to sensing methods based on electrical variation is discussed through further classification according to sensing materials, including metal oxide semiconductors, polymers, carbon nanotubes, and moisture absorbing materials. Methods based on other kinds of variations such as optical, calorimetric, acoustic and gas-chromatographic, are presented in a general way. Several suggestions related to future development are also discussed. Furthermore, this paper focuses on sensitivity and selectivity for performance indicators to compare different sensing technologies, analyzes the factors that influence these two indicators, and lists several corresponding improved approaches.