The effect of SnO2 surface properties on CO2 photoreduction to higher hydrocarbons.

Abstract

Several photocatalysts have been developed for applications in reduction reactions, including tin oxide-based semiconductors. Although its band structure is unfavorable for CO2 reduction reactions, strategies to modify its surface properties directly impacted its activity and selectivity during these reactions. Here, we analyze the influence of heat treatment and decoration of SnO2 with gold nanoparticles on the gas phase CO2 photoreduction process. In both cases, a deleterious effect was observed during reactions under UV radiation (with a drop of 59.81% and 51.45% in CH4 production for SnO2_150°C and SnO2/Au_cop, respectively, compared to SnO2_cop), which is directly related to the availability of surface hydroxyl groups that play a crucial role in CO2 adsorption. Under visible radiation, the gold plasmonic resonance took place in the production of methane (0.33 μmolg 1 for SnO2/Au_cop and 0.29 μmolg 1 for SnO2/Au_150°C), with small amounts of carbon monoxide (0.06 μmolg 1 for SnO2/Au_cop and 0.03 μmolg 1 for SnO2/Au_150°C). These results demonstrate that, though the SnO2 band structure does not indicate a good semiconductor for CO2 reduction, its surface characteristics are responsible for its catalytic activity.