Comparison of Ga2O3 and TiO2 Nanostructures for Photocatalytic Degradation of Volatile Organic Compounds

Abstract

The photocatalytic degradation of formaldehyde, acetaldehyde, toluene, and styrene are compared using monoclinic Ga2O3 and anatase TiO2 nanostructures under ultraviolet-C irradiation. These Ga2O3 and TiO2 photocatalysts are characterized using a field emission scanning electron microscope, a powder X-ray diffraction system, the Brunauer–Emmett–Teller method, and a Fourier transform infrared spectrometer. The Ga2O3 shows a higher reaction rate constant (k, min−1) than TiO2 by a factor of 7.1 for toluene, 8.1 for styrene, 3.1 for formaldehyde, and 2.0 for acetaldehyde. The results demonstrate that the photocatalytic activity ratio of the Ga2O3 over the TiO2 becomes more prominent toward the aromatic compounds compared with the nonaromatic compounds. Highly energetic photo-generated carriers on the conduction/valence band-edge of the Ga2O3, in comparison with that of the TiO2, result in superior photocatalytic activity, in particular on aromatic volatile organic compounds (VOCs) with a high bond dissociation energy.

Impact of Al doping on a hydrothermally synthesized β-Ga2O3 nanostructure for photocatalysis applications

“…9-12 b-Ga 2 O 3 has a high redox potential, which is benecial for photocatalytic reactions under photoexcitation conditions. 9,13 Its redox potential is higher than TiO 2 , so it exhibits better photocatalytic performance than conventional TiO 2 photocatalysts. Meanwhile, the recombination of photogenerated electron-hole pairs is known to severely degrade photocatalytic efficiency; 14,15 when the electron-hole pairs recombine and the carrier concentrations become depleted, the photocatalytic reactions decrease as a consequence.…”

Fast-Response Colorimetric UVC Sensor Made of a Ga2O3 Photocatalyst with a Hole Scavenger

“…Figure 2 a shows the pseudo-first-order kinetics of the MB reduction with different TEOA concentrations (0–15 wt.%). For comparison, the M0 and T0 were also included as a control set of experiments because the MB itself could be slightly reduced upon UVC exposure [ 16 ]. Table 1 includes the specific sample notation for the different TEOA concentrations, along with the linear regression coefficient (coefficient of determination, R 2 ) obtained from Figure 2 a.…”

“…The chemical reduction of the MB solution can be initiated by catalysts such as the Ga 2 O 3 photocatalyst [ 15 ]. The Ga 2 O 3 nanoparticle was in the form of nanorods whose average length was about 3 μm and whose surface area was 32.2 m 2 /g using the Brunauer–Emmett–Teller (BET) method [ 16 ]. The degree of the color change in the MB solution can be used as an indicator of UVC exposure, and in this work, we used the MB reduction rate (MBR) as a numerical indicator of the UVC exposure.…”

Synthesis and Photocatalytic Activity of β-Ga2O3 Nanostructures for Decomposition of Formaldehyde under Deep Ultraviolet Irradiation

“…The photogenerated charge carriers then travel to the surface of β-Ga 2 O 3 where they take part in redox reactions [22,23]. The basic mechanism of photocatalytic decomposition is derived from the oxidation of organisms to H 2 O, CO 2 along with -OH or O 2 radicals produced on the surface of β-Ga 2 O 3 under UCV irradiation [2,8]. In the heterogeneous reaction system, Ga 2 O 3 is excited by the photon energy more so than the band gap energy.…”

“…Gallium oxide (Ga 2 O 3 ) has recently been considered as an attractive alternative due to its long stability and high redox capabilities [6,7]. Yoo et al demonstrated a superior photocatalytic activity of Ga 2 O 3 on VOCs compared to that of TiO 2 [8]. In particular, monoclinic gallium oxide (β-Ga 2 O 3 ) has emerged because of its wide bandgap (4.7-4.9 eV) and unique optical properties [9].…”