Surface Modification of TiO2 for Obtaining High Resistance against Poisoning during Photocatalytic Decomposition of Toluene

Abstract

Titanium oxide (TiO2) nanostructures, the most widely used photocatalysts, are known to suffer from poisoning of the active sites during photocatalytic decomposition of volatile organic compounds. Partially oxidized organic compounds with low volatility stick to the catalyst surface, limiting the practical application for air purification. In this work, we studied the UV-driven photocatalytic activity of bare TiO2 toward toluene decomposition under various conditions and found that surface deactivation is pronounced either under dry conditions or humid conditions with a very high toluene concentration (~442 ppm). In contrast, when the humidity was relatively high (~34 %RH) and toluene concentration was low (~66 ppm), such deactivation was not significant. We then modified TiO2 surfaces by deposition of polydimethylsiloxane and subsequent annealing, which yielded a more hydrophilic surface. We provide experimental evidence that our hydrophilic TiO2 does not show deactivation under the conditions that induce significant deactivation with bare TiO2. Conversion of toluene into dimethylacetamide was observed on the hydrophilic TiO2 and did not result in poisoning of active sites. Our hydrophilic TiO2 shows high potential for application in air purification for extended time, which is not possible using bare TiO2 due to the significant poisoning of active sites.

Atmospheric plasma dielectric barrier discharge: A simple route to produce superhydrophilic TiO2@carbon nanostructure

“…[ 47‐49 ] Moreover, in Figure 9c, the intensity of the carbonyl and carboxyl‐like peaks at 288.3 and 289.1 eV changes with the applied voltage, which is consistent with the change from hydrophobic to hydrophilic behaviors of the nanocomposites. [ 50‐52 ] Beyond 5.2 kV, the surface becomes more hydrophilic, whereas the surface roughness continues to increase, which no more contradicts the Wenzel model. Nevertheless, it is likely that besides surface roughness, surface chemistry still plays a role in determining the surface wettability.…”

Precursor- and waste-free synthesis of spark-ablated nanoparticles with enhanced photocatalytic activity and stability towards airborne organic pollutant degradation

“… 78 Nevertheless, the conventional TiO 2 and ZnO photocatalysts are known to suffer from the poisoning of active sites during the photocatalytic process due to the adsorption of low volatile intermediates and the complete avoidance of catalyst deactivation is not possible. 79,80 For example, the deactivation of almost 37% and 55% in the second and third cycles, respectively, has been reported during toluene degradation on the benchmarked TiO 2 photocatalyst. 81 In our study, the photocatalytic stability was evaluated in four consecutive identical photocatalytic tests using the same sample (Fig.…”

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“…In the case of O-1s (Fig. 3 c) there were two different deconvolutions at 531 eV assigned to PDMS-O [41,42] and 534 eV the from O -Si -O bonds in PDMS [41,43]. Finally, in the case of Si-2p (Fig.…”