Preparation and Catalytic Activity of Thermosensitive Ga₂O₃ Nanorods

Abstract

Gallium oxide (β-Ga 2 O 3 ) nanorods were prepared by ultrasonic irradiation of molten gallium in warm water to form α-GaO(OH). This precursor was then subjected to calcination in air at 600 °C for 3 h to form β-Ga 2 O 3 , as confirmed by Xray diffraction (XRD). Field emission scanning electron microscopy (FE-SEM)/high-resolution transmission electron microscopy (HRTEM) micrographs revealed the formation of well-organized nanotubes/nanorods with homogeneous size distribution. The average length of the β-Ga 2 O 3 nanorods was affected by the temperature of the water during sonication, decreasing from 480 to 72 nm with an increase in the temperature from 25 to 50 °C. A sharp decline in the particle size was also observed when the temperature was above 35 °C. The catalytic activity of the β-Ga 2 O 3 nanorods was examined, as a model, during the dehydration reaction of xylose to furfural. Furfural is a versatile biomass-derived platform compound used for the synthesis of several strategic chemicals. This nanoscale catalyst has a large surface area, which enhances its catalytic activity and enables it to completely convert xylose to furfural at 150 °C within 12 h without any trace of byproducts, as confirmed by highperformance liquid chromatography (HPLC), 13 C nuclear magnetic resonance (NMR), and 1 H NMR. The XRD pattern of the used β-Ga 2 O 3 nanorods was identical to that of pristine Ga 2 O 3 , indicating the possible reusability of this catalyst. β-Ga 2 O 3 was reused for more reduction cycles, with similar results to the freshly prepared β-Ga 2 O 3 . HPLC analysis demonstrated that the selectivity of furfural is up to 94% compared to the 30% obtained with GaO(OH) as a catalyst.

Recent Advances in Aqueous-Phase Catalytic Conversions of Biomass Platform Chemicals Over Heterogeneous Catalysts

“…The catalytic activity of β-Ga 2 O 3 nanorods was examined during the dehydration reaction of xylose to furfural, and results showed that β-Ga 2 O 3 exhibits good activity and selectivity. The 94% yield of furfural is obtained at 150 • C within 12 h (Kumar et al, 2016). The inherent characteristics of the stimuli and thermoresponsiveness for gallium-based oxide nanoparticles catalyst might be key factors leading to higher production of furfural from xylose.…”

Nanostructured Oxides Containing Ga: Materials with Unique Properties for Aqueous-Based Applications

“…For instance, the optoelectronics community is currently addressing the need to produce single crystal Ga 2 O 3 with specific characteristics (i.e., p-type doping and improved thermal conductivity) that are essential for fabricating devices for power electronics . However, advances in the synthesis of nanostructured Ga-based oxide materials has expanded their utility. , Currently, there is an emphasis on understanding their properties in the context of catalysis, sensors, and biomedical modalities, such as targeted drug delivery, chemo/thermal/photodynamic therapy, and in vivo imaging. Properties of particular interest include unique conductivity and photoluminescence .…”

“…1 However, advances in the synthesis of nanostructured Ga-based oxide materials has expanded their utility. 2,3 Currently, there is an emphasis on understanding their properties in the context of catalysis, 4 sensors, 5 and biomedical modalities, 6 such as targeted drug delivery, chemo/thermal/photodynamic therapy, and in vivo imaging. Properties of particular interest include unique conductivity 7 and photoluminescence.…”

Effect of pH and structure on the channel conductivity of AlGaN/GaN heterostructure based sensors

“…Such a surface oxide layer is formed either unintentionally, through prolonged exposure to air or water, or intentionally as a relatively thick layer of crystalline oxide formed by thermal oxidation of the surface. [28] Gallium oxide is a transparent oxide with a wide energy band gap of 4.8 eV [29] which, owing to its material properties, is a promising semiconductor material for a wide range of applications from semiconducting lasers, UV detectors, and high temperature gas sensors, to water splitting, [30,31] catalysis, [32,33] and hydrogen detectors. [34][35][36][37] The electronic transport properties of III-N semiconductors have been investigated extensively.…”