UiO-66(Ce)/Ti₃C₂COOH_x composite for selective visible light-induced methanol oxidation to formaldehyde

The high recombination rate of charge carriers in MOFs significantly limits their photocatalytic performance, necessitating continuous improvement. One effective approach to overcoming this challenge is the integration of MOFs with conductive materials such as MXenes, which can enhance charge separation and improve photocatalytic efficiency. On the other hand, there is a growing need to develop greener routes for formaldehyde production, making the advancement of efficient and sustainable photocatalytic systems even more crucial. Herein, an intimately connected UiO-66(Ce)/Ti₃C₂COOH_x composite was obtained by connecting cerium ions from UiO-66(Ce) with carboxylic groups present on functionalized MXene surface, which was proven by spectroscopic methods. The band structure of UiO-66(Ce) was investigated, establishing HOCO and LUCO at 2.32 eV and −0.54 eV respectively. Prepared composites with varying amounts of Ti₃C₂COOH_x were tested for photocatalytic formaldehyde production. Production of formaldehyde through photocatalysis under visible light irradiation (λ > 420 nm) with a composite that contained 1.5 % of Ti₃C₂COOH_x has reached concentrations of 7.08 µg/ml. Retaining its stability for up to 4 cycles. Additionally, the aid of hole scavengers resulted in a better understanding of photocatalytic reaction mechanism. Obtained material has the potential to revolutionize formaldehyde production in terms of safety, efficiency, cost-effectiveness, and sustainability.