Synthesis and characterization of V2O5-Ga2O3 photocatalysts and their application on the photocatalytic reduction of CO2

Abstract

The photocatalytic reduction of carbon dioxide (CO₂) to produce methanol (CH₃OH) is a promising strategy for producing clean energy. The catalyst, the aqueous medium, and the UV light are key parameters for the formation of the most relevant pair (e^-/h⁺) and the specific selectivity towards the desired product (methanol). The use of Ga₂O₃ and V₂O₅ in the photocatalytic reduction of CO₂ to produce methanol has been little studied. However, the combination of these oxides is important to generate synergies and decrease the band energy, enhancing the photocatalytic activity in CO₂ reduction. In this work, V₂O₅-Ga₂O₃ combined photocatalysts have been prepared and investigated for the photocatalytic reduction of CO₂. These photocatalysts were characterized by spectroscopic and microscopic techniques. The results showed that textural properties such as surface area and morphology do not influence the photocatalytic activity. However, species such as Ga2p_3/2 and Ga2p_1/2 identified by XPS enhanced the photocatalytic activity, most likely due to the formation of vacancies and the reduction of the bandgap in the combined oxides, as compared to single oxides. The contribution of these factors in pair interactions (e^-/h⁺) with CO₂ to generate methanol is demonstrated.

Keywords: Carbon dioxide; Gallium oxide; Methanol; Photocatalysts; Photocatalytic reduction; Vanadium oxide.