Function-led design of multifunctional stimuli-responsive superhydrophobic surface based on hierarchical graphene-titania nanocoating

Multifunctional smart superhydrophobic surface with full-spectrum tunable wettability control is fabricated through the self-assembly of the graphene and titania nanofilm double-layer coating. Advanced microfluidic manipulative functions, including directional water transport, adhesion & spreading controls, droplet storage & transfer, and droplet sensing array, can be readily realized on this smart surface. An in-depth mechanism study regarding the underlying secrets of the tunable wettability and the UV-induced superhydrophilic conversion of anatase titania are also presented

Semiconducting Metal Oxide Based Sensors for Selective Gas Pollutant Detection

A review of some papers published in the last fifty years that focus on the semiconducting metal oxide (SMO) based sensors for the selective and sensitive detection of various environmental pollutants is presented

Hydrogen Sensor Application of Anodic Titanium Oxide Nanostructures

Hydrogen (H2) fuel cells have been considered a promising renewable energy source. The recent growth of H2 economy has required highly sensitive, micro-sized and cost-effective H2 sensor for monitoring concentrations and alerting to leakages due to the flammability and explosiveness of H2 Titanium dioxide (TiO2) made by electrochemical anodic oxidation has shown great potential as a H2 sensing material. The aim of this thesis is to develop highly sensitive H2 sensor using anodized TiO2. The sensor enables mass production and integration with microelectronics by preparing the oxide layer on suitable substrate. Morphology, elemental composition, crystal phase, electrical properties and H2 sensing properties of TiO2 nanostructures prepared on Ti foil, Si and SiO2/Si substrates were characterized. Initially, vertically oriented TiO2 nanotubes as the sensing material were obtained by anodizing Ti foil. The morphological properties of tubes could be tailored by varying the applied voltages of the anodization. The transparent oxide layer creates an interference color phenomena with white light illumination on the oxide surface. This coloration effect can be used to predict the morphological properties of the TiO2 nanostructures. The crystal phase transition from amorphous to anatase or rutile, or the mixture of anatase and rutile was observed with varying heat treatment temperatures. However, the H2 sensing properties of TiO2 nanotubes at room temperature were insufficient. H2 sensors using TiO2 nanostructures formed on Si and SiO2/Si substrates were demonstrated. In both cases, a Ti layer deposited on the substrates by a DC magnetron sputtering method was successfully anodized. A mesoporous TiO2 layer obtained on Si by anodization in an aqueous electrolyte at 5°C showed diode behavior, which was influenced by the work function difference of Pt metal electrodes and the oxide layer. The sensor enabled the detection of H2 (20-1000 ppm) at low operating temperatures (50–140°C) in ambient air. A Pd decorated tubular TiO2 layer was prepared on metal electrodes patterned SiO2/Si wafer by anodization in an organic electrolyte at 5°C. The sensor showed significantly enhanced H2 sensing properties, and detected hydrogen in the range of a few ppm with fast response/recovery time. The metal electrodes placed under the oxide layer also enhanced the mechanical tolerance of the sensor. The concept of TiO2 nanostructures on alternative substrates could be a prospect for microelectronic applications and mass production of gas sensors. The gas sensor properties can be further improved by modifying material morphologies and decorating it with catalytic materials.Siirretty Doriast

Micro-Fabricated Hydrogen Sensors Operating at Elevated Temperatures

In this dissertation, three types of microfabricated solid-state sensors had been designed and developed on silicon wafers, aiming to detect hydrogen gas at elevated temperatures. Based on the material properties and sensing mechanisms, they were operated at 140°C, 500°C, and 300°C. The MOS-capacitor device working at 140°C utilized nickel instead of the widely-used expensive palladium, and the performance remained excellent. For very-high temperature sensing (500°C), the conductivity of the thermally oxidized TiO2 thin film based on the anodic aluminum oxide (AAO) substrate changed 25 times in response to 5 ppm H2 and the response transient times were just a few seconds. For medium-high temperatures (~300°C), very high sensitivity (over 100 times’ increment of current for H2 concentration at 10 ppm) was obtained through the reversible reduction of the Schottky barrier height between the Pt electrodes and the SnO2 nano-clusters. Fabrication approaches of these devices included standard silicon wafer processing, thin film deposition, and photolithography. Materials characterization methods, such as scanning electron microscopy (SEM), atomic force microscopy (AFM), surface profilometry, ellipsometry, and X-ray diffractometry (XRD), were involved in order to investigate the fabricated nano-sized structures. Selectivities of the sensors to gases other than H2 (CO and CH4) were also studied. The first chapter reviews and evaluates the detection methodologies and sensing materials in the current research area of H2 sensors and the devices presented this Ph.D. research were designed with regard to the evaluations

Titanium Dioxide

This book presents a comprehensive overview of titanium dioxide, including recent advances and applications. It focuses on the compound’s uses in environmental remediation, photocatalytic materials, rechargeable lithium-ion batteries, thin films, energy storage, semiconductors, and much more. This volume is a useful resource for researchers, scientists, engineers, and students

FIRB "SQUARE" project: nano-structured sensors for the detection of the polluting in engine exhaust gases and for indoor air quality monitoring

The present work is a final dissemination of activities carried out and main results obtained in the national founded project Firb "Square". The project is leaded by Centro Ricerche Fiat and it involves the most qualified national public Research Institutes and Universities active in the fields of nanomaterials synthesis, nanotechnology and gas sensors development

A STUDY OF FACTORS AFFECTING ENTREPRENEURIAL INTENTION: THE MODERATING ROLE OF INDIVIDUALISM

The main purpose of this study is to identify the factors which affect the entrepreneurial intention (EI) of the university students of Gilgit-Baltistan. This research study mainly focuses on the theory of planned behaviour (TPB) and Hofstede national culture dimension of individualism. The quantitative research method was applied for the data analysis. The data were collected from the public sector universities of Gilgit-Baltistan with the total number of 362 final year students. Moreover, to test the hypothesis of the study structural equation modeling (PLS-SEM) version 4.0 software were used for the data analysis and interpretation. The findings of the research are follows: i) attitude towards behaviour positively influence the entrepreneurial intention of the university students ii) subjective norms also significantly affect the entrepreneurial intention iii) perceived behaviour control has a positive effect on the entrepreneurial intention of the university students. However, the moderating variable of individualism does not moderate the relationship between TPB and EI. Moreover, this research study provides a comprehensive research model which includes the behavioural, and culture factors that were analyzed and validated through empirical evidence. It is also one of the pioneer research conducted in the rural areas i.e. Gilgit-Baltistan of Pakistan

Nanocomposite Films for Gas Sensing

Nanocomposite films are thin films formed by mixing two or more dissimilar materials having nano-dimensional phase(s) in order to control and develop new and improved structures and properties. The properties of nanocomposite films depend not only on the individual components used but also on the morphology and the interfacial characteristics. Nanocomposite films that combine materials with synergetic or complementary behaviours possess unique physical, chemical, optical, mechanical, magnetic and electrical properties unavailable from that of the component materials and have attracted much attention for a wide range of device applications such as gas sensors.NRC publication: Ye