The Effect of SnO2 Surface Properties on CO2 Photoreduction to Higher Hydrocarbons

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 degrees 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 mu mol g(-1) for SnO2/Au_cop and 0.29 mu mol g(-1) for SnO2/Au_150 degrees C), with small amounts of carbon monoxide (0.06 mu mol g(-1) for SnO2/Au_cop and 0.03 mu mol g(-1) for SnO2/Au_150 degrees 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.

Automated summary

The influence of heat treatment and decoration of SnO2 with gold nanoparticles on CO2 photoreduction process was analyzed. Both treatments had a deleterious effect on the reactions, with a significant drop in methane production under UV radiation. However, under visible radiation, the decorated SnO2 showed plasmonic resonance and produced methane with small amounts of carbon monoxide. These results demonstrate that the surface characteristics of SnO2 are responsible for its catalytic activity, despite its unfavorable band structure for CO2 reduction.