Synthesis and characterization of V 2 O 5 -Ga 2 O 3 photocatalysts and their application on the photocatalytic reduction of CO 2

The photocatalytic reduction of carbon dioxide (CO 2 ) to produce methanol (CH 3 OH) 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 Ga 2 O 3 and V 2 O 5 in the photocatalytic reduction of CO 2 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 CO 2 reduction. In this work, V 2 O 5 -Ga 2 O 3 combined photocatalysts have been prepared and investigated for the photocatalytic reduction of CO 2 . 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 CO 2 to generate methanol is demonstrated.