PREPARATION AND CHARACTERIZATION OF HYBRID PHORPHYRIN-TIN DIOXIDE CHEMICAL SENSORS

Hybrid Co porphyrin-SnO2 and pure SnO2 thin films deposited by sol-gel technique have been used as sensing materials for the development of chemical sensors. Gas sensing tests towards different concentrations of CH3OH and CO for different working temperature have been carried out. Best results have been obtained with CoTPP-SnO2 material in comparison. with the single oxide SnO2 towards methanol vapours at 250°C working temperature, supporting the presence of a catalytic effect of the CoTPP, which is not thermally decomposed at this temperature, as confirmed by optical measurements, while at higher temperature, where the porphyrin is thermally decomposed, a sharp decrease of responses was observed. In the case of CO no significant differences were observed, showing that metalloporphyrins can be used to modify the selectivity of SnO2 sensors.