Effect of CuO synthesis on the activity and selectivity of MCM-41/CuO composites in the CO₂ photoreduction process

Composites were synthesized using two distinct methods: salt impregnation and coprecipitation, and characterized using various techniques. Both methods yielded composites with high surface area and band gap energy in the visible electromagnetic spectrum. Pure MCM-41 and MCM-41/CuO composites exhibited potential for CO2 photoreduction, where the composition and different active sites of the photocatalysts played a critical role in the activity and selectivity of the products formed. Composites containing 1% of the CuO obtained by both methods showed higher ethylene production compared to MCM-41, but the materials obtained by the impregnation method demonstrated lower photocatalytic activity than MCM-41 and the composites obtained by the coprecipitation method. These results highlight the versatility of MCM-41 in forming composites with semiconductors and the importance of understanding the key factors that influence CO2 photoreduction and composite selectivity, including their surface, structural, and electrical characteristics.