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Journal of Physical Studies 26(2), Article 2802 [7 pages] (2022)
DOI: https://doi.org/10.30970/jps.26.2802 PHOTOCATALYTIC ACTIVITY OF NANOSIZED ZnO:HO FILMS DEPOSITED BY EXPLOSIVE EVAPORATION AT DEGRADATION OF TOLUENE IN AIR
A. M. Kasumov
Frantsevich Institute for Problems in Materials Science,
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One of the most promising methods of air purification today is photocatalytic oxidation of gas-phase and liquid-phase environmental pollutants of chemical and biological origin under the action of soft ultraviolet radiation to obtain non-harmous components of air: water and CO$_2$. The photocatalytic properties of thickness-nanosized ZnO:Ho films obtained by electron beam explosive evaporation have been studied during degradation of toluene in air under ultraviolet (365 nm) irradiation. Methods for holmium doping of ZnO and explosive evaporation were chosen with a view to using them for air purification from volatile toluene compounds. The photocatalytic activity was studied depending on the following parameters: exposure time, temperature, humidity, initial toluene concentration in the air, and Ho content in ZnO. It was stated that the kinetics of photocatalytic decomposition of air toluene over film ZnO:Ho is close to the first-order reaction. The temperature dependence of the photocatalytic process is described by the Arrhenius equation. The rate and energy of adsorption activation of thermo- and photocatalysis of toluene on the ZnO:Ho film surface are calculated. The highest photocatalytic activity is achieved at the air humidity above 50%, initial concentration of toluene in the air below $2.5 · 10^{-5} \frac{\rm mol}{\rm L}$, and the Ho content in ZnO of 3 at.%. As the Ho content in ZnO increases from 0 to 3 at.%, the rate of toluene degradation increases by 30%. The photocatalytic degradation of toluene over the ZnO:Ho film reaches the final stage with the formation of CO$_2$ gas.
Key words: photocatalytic activity, toluene, humidity, ZnO:Ho, concentration, CO2.
