The influence of the addition of carbon spheres on photoactivity of TiO2 and ZnO in CO2 reduction process

Abstract

The development of an effective photocatalyst for CO2 reduction is currently being addressed by many scientists. This study concerns the influence of the addition of carbon spheres (CS) on photoactivity of TiO2 and ZnO. The photocatalysts were tested in a liquid phase system in an alkaline environment. The suspensions of the tested materials were irradiated with UV–Vis light for 6 h. Then, the amount of the obtained products in the gas phase was analysed by gas chromatography. The identified products of CO2 photoreduction were hydrogen, carbon monoxide, and methane. Based on the results, it was found that CS/TiO2 and CS/ZnO showed similar activity in carbon dioxide reduction processes, however, more product amounts were obtained in experiments with the use of CS/TiO2 materials. The addition of carbon spheres to titanium dioxide improved its activity in carbon monoxide production. The maximum photoactivity of CS/TiO2 was observed for the addition of 0.1 g of CS. On the other hand, in the case of CS/ZnO materials, carbon spheres did not positively affect their performance. Nevertheless, their activity increased with the CS amount.

Keywords

• Photocatalysis
• Carbon spheres
• Titanium dioxide
• Zinc oxide
• Carbon dioxide