||This study applied sputtering technology to prepare composite film|
photocatalyst TiO2/ITO for investigating the decomposition efficiency of
acetone using composite TiO2/ITO made by single- and multi-layer
processes. The influences of operating parameters, including sputtering
operating parameters and photocatalytic operating parameters, on the
decomposition efficiency of acetone were further investigated.
Operating parameters investigated for the sputtering process included
oxygen to argon ratio (O2/Ar), temperature, substrate, sputtering dutation,
and sputtering layers, while operating parameters investigated for the
photocatalytic decomposition of acetone included light wavelength, H2O
concentration, O2 concentration, initial acetone concentration, and the
type of photocatalysts.
In the experiments, acetone was degraded by the composite film
photocatalyst TiO2/ITO in a self-designed batch photocatalytic reactor.
Operating parameters included light wavelength (350~400 nm, 435~500
nm, 506~600 nm), the type of photocatalysts (single-layer film
photocatalyst TiO2/ITO with the thickness of 355.3, 396.6, 437.5, 487.5,
and 637.5 nm; double- and triple-layer TiO2/ITO), H2O concentration (0,
50, 100, 200, and 300 ppm). The incident light with different
wavelength irradiated with three 15-W lamps of near UV light or LED
lamps of blue and green lights placed on the top of the photocatalytic
reactor. Acetone was injected into the reactor by using a gasket syringe
and vaporized for further photocatalytic degradation on the film
photocatalyst TiO2/ITO placed at the bottom of the reactor. Air samples
were taken to analyze acetone concentration with a GC/FID.
The composite film photocatalyst TiO2/ITO was mainly composed
of anatase with a few rutile. The thicknesses of the single- and
double-layer film photocatalyst with the thickness of 473.5 nm and 506.0
nm, respectively. Experimental results indicated that the highest
decomposition efficiency of acetone was obtained by using TiO2/ITO,
followed by TiO2/ground glass and TiO2/glass. The highest
decomposition efficiency of acetone was observed by using TiO2/ITO at
50°C, 20% O2, and 100 ppm H2O. In the kinetic model, the acetone
decomposition of single-layer TiO2/ITO was zero-order reaction. The
acetone decomposition of double-layer TiO2/ITO in high initial acetone
concentration was zero-order reaction, while that in low initial acetone
concentration was first-order reaction. Thus, the decomposition of
acetone exerted by TiO2 film photocatalyst can be enhanced efficiently by
ITO. Under the incidence of blue light, the reaction rate of acetone
decomposition were 2.353×10-5 and 3.478×10-5 μmole/cm2-s for using
single- and double-layer TiO2/ITO, respectively.
Finally, a bimolecular Langmuir-Hinshelwood (L-H) kinetic model
was applied to simulate the influences of initial acetone concentration,
temperature, and relative humidity on the promotion and inhibition for
the photocatalytic degradation of acetone. This study revealed that the
L-H kinetic model could successfully simulate the photocatalytic reaction
rate of acetone.