EFFECTS OF SYNTHESIS PARAMETERS ON THE STRUCTURE OF TITANIA NANOTUBES

Detection of hydrogen is crucial for industrial process control and medicalapplications where presence of hydrogen in breath indicates different type ofhealth problems particularly in infants. A better performed sensor with highsensitivity, selectivity, reliability and faster response time would be critical andsought after especially for medical applications. Titanium dioxide nanotubestructure is chosen as an active component in the gas sensor because of itshighly sensitive electrical resistance to hydrogen over a wide range ofconcentrations. The objective of the work is to investigate the effect of theanodizing conditions on the structure of titania nanotubes produced byanodizing method. The anodizing parameters namely the ambient temperatureand separation of electrodes are varied accordingly to find the optimumanodizing conditions for production of good quality titania nanotubes forenhanced properties based on their uniformity, coverage, pore size andcrystallinity. Samples of nanotubes produced were subjected to annealingprocess at varying time and temperature in order to improve the crystallinity ofthe nanotubes. The highly ordered porous titania nanotubes produced by thismethod are of tabular shape and have good uniformity and alignment over largeareas. The pore size of the titania nanotubes ranges from 47 to 94 nm, while thewall thickness is in the range of 17 to 26 nm. The length of the nanotubes wasfound to be about 280 nm. The structure of nanotubes changes from amorphousto crystalline after undergoing annealing treatment. Nanotubes have also shownto have better crystallinity if they were subjected to annealing treatment athigher temperature. The characteristics of nanotubes obtained are found to beagreeable to those that have been reported to show improved hydrogen gassensing properties.