Effect of Pd-Sensitization on Poisonous Chlorine Gas Detection Ability of TiO 2 : Green Synthesis and Low-Temperature Operation

Ganoderma lucidum mushroom-mediated green synthesis of nanocrystalline titanium dioxide (TiO ) is explored via a low-temperature (≤70 °C) wet chemical method. The role of Ganoderma lucidum mushroom extract in the reaction is to release the ganoderic acid molecules that tend to bind to the Ti metal ions to form a titanium-ganoderic acid intermediate complex for obtaining TiO nanocrystallites (NCs), which is quite novel, considering the recent advances in fabricated gas sensing materials. The X-ray powder diffraction, field emission scanning electron microscopy, Raman spectroscopy, and Brunauer-Emmett-Teller measurements etc., are used to characterize the crystal structure, surface morphology, and surface area of as-synthesized TiO and Pd-TiO sensors, respectively. The chlorine (Cl ) gas sensing properties are investigated from a lower range of 5 ppm to a higher range of 400 ppm. In addition to excellent response-recovery time, good selectivity, constant repeatability, as well as chemical stability, the gas sensor efficiency of the as-synthesized Pd-TiO NC sensor is better (136% response at 150 °C operating temperature) than the TiO NC sensor (57% at 250 °C operating temperature) measured at 100 ppm (Cl ) gas concentration, suggesting that the green synthesized Pd-TiO sensor demonstrates efficient Cl gas sensing properties at low operating temperatures over pristine ones.