Influence of PEG 6000 on gallium oxide (Ga2O3) polymorphs and photocatalytic properties

Three different nanorod-like gallium oxides with mono/poly-crystalline nature (α, β, and α/β-Ga 2 O 3 ) were prepared by regulating the amount of polyethylene glycol (PEG) 6000 in the range of 0.2–0.8 g proportionally via a hydrothermal method combined with further calcination. The bandgap of the products, given by UV-Vis diffuse reflectance spectra (UV-Vis DRS), was in the order of α-Ga 2 O 3 > α/β-Ga 2 O 3 > β-Ga 2 O 3 . To further investigate the photocatalysis performance of the catalysts, the decomposition of rhodamine B (RhB) by Ga 2 O 3 under UV light illumination ( λ < 387 nm) was presented and complete degradation could be achieved within 30 min, a result that showed the highest efficiency. The photocatalytic oxidation mechanism is further discussed and prominently related to the active species: hydroxyl radical (·OH) and superoxide radical (O 2 · − ), which were confirmed by electron paramagnetic resonance (EPR).