Metalloporphyrin-decorated semiconducting oxides for gas sensing applications
type: CreativeWork
description: The air quality and environmental problems have attracted more and more researchers’ attention in the past few decades. Since Taguchi released the first practical semiconductor gas sensor applied to the market, more and more researchers have invested in the research on the improvement and application of semiconductor gas sensors and a large number of modified tin oxide gas sensors with various gas sensing properties have been reported in the past few decades. This project has created new solid-state materials of metalloporphyrin-decorated metal oxides for gas sensing applications, directed at the measurement of nitrogen dioxide at low concentration in air. The hypothesis was that metalloporphyrins grafted onto the surface of tin dioxide could act as electronic surface states, such that changes in the energy or electron occupancy of the highest occupied molecular orbital of the porphyrin would be reflected in changes of the conductivity of the tin dioxide. Adsorption of nitrogen dioxide as an axial ligand of the porphyrin would then be signalled by a change in electrical conductivity. Tin dioxide doped with In(III) was successfully synthesised. This was a metastable material since In(III) is known to be insoluble in SnO2. Successful substitution of indium was signalled by a significantly decreased electrical conductivity , such that the effect of adsorption of surface donor states could be observed, and confirmed by X-ray photoelectron spectroscopy (XPS). Ruthenium(II)-carbonyl, platinum and palladium porphyrins having peripheral carboxylic acid groups were synthesised: the peripheral carboxylate being presumed, from literature studies, important to secure ‘flat-on’ adsorption of the porphyrin onto the oxide. All porphyrins and metalloporphyrins were fully characterized by 1H NMR, UV-Vis, IR and MS and the metal oxides fully characterized by powder XRD, SEM, EDS, XPS and BET adsorption. The increase in electrical conductivity of the oxide consequent on adsorption of …
abstract: The air quality and environmental problems have attracted more and more researchers’ attention in the past few decades. Since Taguchi released the first practical semiconductor gas sensor applied to the market, more and more researchers have invested in the research on the improvement and application of semiconductor gas sensors and a large number of modified tin oxide gas sensors with various gas sensing properties have been reported in the past few decades. This project has created new solid-state materials of metalloporphyrin-decorated metal oxides for gas sensing applications, directed at the measurement of nitrogen dioxide at low concentration in air. The hypothesis was that metalloporphyrins grafted onto the surface of tin dioxide could act as electronic surface states, such that changes in the energy or electron occupancy of the highest occupied molecular orbital of the porphyrin would be reflected in changes of the conductivity of the tin dioxide. Adsorption of nitrogen dioxide as an axial ligand of the porphyrin would then be signalled by a change in electrical conductivity. Tin dioxide doped with In(III) was successfully synthesised. This was a metastable material since In(III) is known to be insoluble in SnO2. Successful substitution of indium was signalled by a significantly decreased electrical conductivity , such that the effect of adsorption of surface donor states could be observed, and confirmed by X-ray photoelectron spectroscopy (XPS). Ruthenium(II)-carbonyl, platinum and palladium porphyrins having peripheral carboxylic acid groups were synthesised: the peripheral carboxylate being presumed, from literature studies, important to secure ‘flat-on’ adsorption of the porphyrin onto the oxide. All porphyrins and metalloporphyrins were fully characterized by 1H NMR, UV-Vis, IR and MS and the metal oxides fully characterized by powder XRD, SEM, EDS, XPS and BET adsorption. The increase in electrical conductivity of the oxide consequent on adsorption of …
author: Lu, Ziqi
license: https://researchspace.auckland.ac.nz/docs/uoa-docs/rights.htm
date published: 2020
date modified: 2026-07-24T01:03:18Z
provider: University of Auckland
publisher: Networked Digital Library of Theses and Dissertations
type: WebPage
source organization: ResearchSpace@Auckland

PropertyValue
property ID: Handle
value: https://hdl.handle.net/2292/53430