A Method for Integrating ZnO Coated Nanosprings into a Low Cost Redox-Based Chemical Sensor and Catalytic Tool for Determining Gas Phase Reaction Kinetics

Abstract

Abstract:A chemical sensor (chemiresistor) was constructed from a xenon light bulb by coating it with a 3-D zinc oxide coated silica nanospring mat, where the xenon light bulb serves as the sensor heater. The sensor response to toluene as a function of xenon light bulb sensor temperature (T LB ) and vapor temperature (T V ) was observed and analyzed. The optimum operational parameters in terms of T LB and T V were determined to be 435 °C and 250 °C, respectively. The activation energy of toluene oxidation (E d ) on the ZnO surface was determined to be 87 kJ· mol −1 , while the activation energy of oxidation (E a ) of the depleted ZnO surface was determined to be 83 kJ· mol −1 . This study serves as proof of principle for integrating nanomaterials into an inexpensive sensor platform, which can also be used to characterize gas-solid, or vapor-solid, redox processes.

Analysis of the kinetics of surface reactions on a zinc oxide nanosheet-based carbon monoxide sensor using an Eley–Rideal model

“…If the recovery curves are considered instead, an alternative estimate of 63 ± 10 kJ mol -1 is obtained. These values are of similar magnitude to the activation energies of similar processes reported elsewhere; separate investigations into the ionisation of oxygen at the surface of ZnO report activation energies of 69 kJ mol -1 [32] and 83 kJ mol -1 [33], while another study calculates the energy barrier for the formation of Oions on TiO 2 as approximately 77 kJ mol -1 [34]. Fig.…”

Nanopiezoelectric Devices for Energy Generation Based on ZnO Nanorods/Flexible-Conjugated Copolymer Hybrids Using All Wet-Coating Processes

“…The piezoelectric effect of the ZnO nanostructure is due to its wurtzite hexagonal structure (space group P6 3mc ), where the Zn 2+ and O 2− ions form a tetrahedral coordination ionic crystals that lacks a center of symmetry, with lattice parameters of a = 0.325 nm and c = 0.521 nm [38][39][40][41]. In addition, ZnO is a crystal with polar surfaces, such as a positive polar plane (0001) rich in Zn 2+ ions and a negative polar plane (000l) rich in O 2− ions, where the interaction of the polar surfaces produces the formation of a variety of unique nanostructures, such as nanospring [42][43][44][45][46][47][48][49], nanohelices [50,51], etc. The ZnO nanomaterial application versatility is certainly relied on the diversification of ZnO crystal morphology, including rod [52,53], wire [54,55], and particle [56,57], with different size, shape, crystal density, crystallinity, and crystal orientation.…”

Signal-to-Noise Enhancement of a Nanospring Redox-Based Sensor by Lock-in Amplification

“…In addition, they can be used for environmental monitoring [ 1 , 2 ] and to detect hazardous materials, such as explosives vapors [ 3 , 4 , 5 , 6 , 7 , 8 , 9 ]. Redox-based sensors, or artificial noses, convert chemical information specific to the analyte into analytical electrical signals [ 4 , 5 , 6 , 7 , 8 , 9 , 10 , 11 , 12 , 13 , 14 , 15 , 16 , 17 , 18 ]. Hence, they are also excellent scientific tools to analyze molecular interactions at surfaces, be it physisorption or chemisorption.…”

“…Hence, they are also excellent scientific tools to analyze molecular interactions at surfaces, be it physisorption or chemisorption. The use of metal oxide nanocrystalline thin films, as well as other more complex nano-morphologies, in the capacity of gas sensitive layers in chemiresistors is well documented [ 4 , 5 , 6 , 7 , 8 , 9 , 10 , 11 , 12 , 13 , 14 , 15 , 16 , 17 , 18 ]. For metal oxides, the sensing mechanism of the sensors (chemiresistors) is attributed to the depletion, or repletion, of the oxygen at a metal oxide semiconductor (MOS) surface.…”