functionalized zno microbelt as improved co sensor

Abstract Miniaturized gas sensors are increasingly important to monitor the quality of air in a wide range of human environments. Semiconductor metal oxides have proved to be a useful family of materials, in this direction. Unfortunately, metal oxide sensors need a high temperature to respond to any target gas. In order to work around this limit, we fabricate hybrid sensors consisting in single zinc oxide microbelts decorated with organic molecules. Fluorinated tetraphenylporphyrin (H 2 TTPF) is deposited via supersonic molecular beam and considerably improve the performance of the microsensor. The microdevice is investigated with XRD, SEM and AFM techniques. While the as-is ZnO microbelt shows no response up to 150°C, the H 2 TTPF decorated microsensor shows a clear and quick response even at 75°C

Recent Progress in Ohmic/Schottky-Contacted ZnO Nanowire Sensors

We review the recent progress of zinc oxide (ZnO) nanowire sensors with ohmic-contacted and Schottky-contacted configurations and the enhancement of the performances of Schottky-contacted ZnO NW sensors (SCZNSs) by the piezotronic effect. Comparing with the traditional ohmic-contacted ZnO NW sensors (OCZNSs), the SCZNSs have higher sensitivities and faster responses controlled by the barrier height at the metal-semiconductor (M-S) interface. The piezotronic effect was applied to tune the Schottky barrier height (SBH) with the strain-induced piezoelectric polarization charges at the interface of the M-S contact. The piezotronic effect can thus improve the detection limitation, sensitivity, and response time of the SCZNSs in different applications, such as UV detection, gas and bio/chemical sensing. These piezotronic-enhanced SCZNSs may find potential applications in human-machine interfacing and flexible electronics skin technologies

Piezotronics/piezo-phototronics: Devices and applications

Piezoelectric effect has been widely used in electromechanical sensing, actuation and energy harvesting, which produces polarization charges under mechanical deformation in materials lacking inversion symmetry or with polarization domains. Conventional piezoelectric materials such as PZT and PVDF are electrically insulating and hence not feasible for constructing functional electronics or optoelectronics. The effect of mechanically-induced polarization on electronic and optoelectronic processes of charge carriers in piezoelectric materials has therefore been long overlooked. Semiconductor materials such as ZnO, GaN and CdS with wurtzite or zinc blende structures also possess piezoelectric properties but are not as extensively utilized in piezoelectric sensors and actuators as PZT due to their relatively small piezoelectric coefficients. The coupling of piezoelectric polarization with semiconductor properties in these materials has resulted in both novel fundamental phenomenon and unprecedented device applications, leading to the increasing research interests in the emerging field of piezotronics and piezo-phototronics. The basic of piezotronics and piezo-phototronics lies in the fact that strain-induced polarization charges at interface can effectively modulate the local band structure and hence the charge carrier transport across local junctions/contacts by exerting substantial influence on the concentration/distribution of free carriers and interfacial electronic charged states in the device. Fundamental physics about the piezotronics and piezo-phototronics are systematically illustrated at first in this dissertation. Functional electronic/optoelectronic devices based on piezoelectric semiconductor materials are presented to demonstrate the practical applications of the piezotronic and piezo-phototronic effects, including nanowire/microwire transistors, nanowire logic circuits, bio/chemical sensors and photo detectors. By successfully applying the piezotronic and piezo-phototronic effects in a wide range of electronics/optoelectronics, we have shown the universality of these two effects to be utilized in various practical applications as effective approaches to modify the physical properties of charge carriers in piezoelectric semiconductors.Ph.D

A Motivational Mechanism Framework for Teachers' Online Informal Learning and Innovation During the COVID-19 Pandemic

Online informal learning (IL) spreads quickly in the COVID-19 Pandemic. Studies have predicted that both online and workplace IL have potential value to individual and organization development, whereas the study on its link with innovation remains scarce. IL is an individualized learning pattern different from formal learning, and its functioning mechanism on innovation will deepen our understanding of the relationship between learning and innovation. Self-efficacy and autonomous motivation are considered as two streams of motivational mediating mechanisms to innovation. However, previous studies have proceeded largely in separation from each other. Researchers highlight the need to develop a more fine-grained theory of motivation and innovation. In addressing these literature gaps, this paper takes college teachers as the sample and focuses on the motivational mediating mechanism between online IL and innovation. The results showed that teachers IL could positively predict innovative teaching performance. Personal teaching efficacy and autonomous motivation played as sequential mediators on the link between IL and innovative teaching performance. This study extends the literature of IL–innovation relationship and enriches understanding of cognition-oriented motivation theory, highlighting one's internal autonomous construction is the key to innovation. Theoretical and practical implications for psychological empowerment are discussed.</jats:p

Highly flexible, conductive and catalytic Pt networks as transparent counter electrodes for wearable dye-sensitized solar cells

We present a highly flexible dye-sensitized solar cell composed of TiO2 nanotube arrays (TNARs) as the photoanode and a transparent Pt network electrode as the counter electrode (CE).</p

Wholesale Price Discrimination in Global Sourcing

Problem definition : We investigate wholesale price discrimination in a global sourcing marketplace. Academic/practical relevance : Previous research has found price discrimination in business-to-consumer markets, in which buyers are end customers. There is limited research on suppliers’ price-quoting behaviors and price discrimination in business-to-business (B2B) markets. It is unclear whether certain characteristics of B2B buyers, who are often representatives of firms and not end customers, would influence suppliers’ pricing decisions. Methodology : We collaborate with a global trading company that runs a field experiment on a B2B platform. Results : We find that there is no significant difference in the wholesale prices quoted to buyers selling in U.S. and South African markets. We also find that suppliers quote significantly higher wholesale prices to white buyers than to Asian and black buyers regardless of country. However, price discrimination disappears when buyers present market information to suppliers, providing the lowest wholesale price offered by other suppliers in the market, whereas price discrimination remains when buyers present social information to suppliers, thereby indicating the buyer is referred by a previous customer. In addition, we show that market information can help buyers obtain a lower wholesale price because it signals a lower willingness to pay. Social information, however, can reduce price quotes for only black and white buyers but not for Asian (particularly Chinese) buyers. Managerial implications : Our work can provide guidance to suppliers’ pricing strategies, buyers’ inquiry strategies, and B2B platforms’ information strategies to attract and retain users. </jats:p