Impact of titanium on the catalytic activity of Zn–BDC and Cu–BDC thin films in the photoreduction of CO₂

Abstract The present text deals with the study of thin films of metal–organic frameworks (MOF) materials based on Zn–BDC, Cu–BDC, and their modified versions with titanium incorporations at 5 and 10% mol. These materials were synthesized by chemically assisted vapor deposition (AACVD) technique and characterized by various techniques such as X-ray diffraction (XRD), scanning electron microscopy (SEM), Raman spectroscopy, band gap determination, and photoluminescence spectroscopy. The results indicated that the incorporation of titanium modifies the structural, optical, and electronic properties of these MOFs, decreasing their band gap and altering their light absorption and emission characteristics. Furthermore, their efficiency as photocatalysts in the photoreduction of CO₂ in an aqueous system was evaluated, using liquid chromatography (HPLC) to analyze the products. It was found that Cu–BDC exhibited higher efficiency compared to Zn–BDC, and the incorporation of titanium significantly improved the catalytic activity of both materials. The 10% Ti–Cu–BDC showed the highest efficiency, with a total yield of 344 mmol/L of products and a conversion efficiency of 56.4%. These results suggest that modification of MOFs with titanium is an effective strategy to optimize their performance in CO₂ photoreduction and other environmental and energy applications.