Modulating the local electron distribution of reo-NH2-UiO-66 through Fc-CHO functionalization for the effective photodegradation of single and mixed VOCs

Ligand functionalization could effectively modulate the local electron distribution of MOFs, thus improving their performance in both the capturing and photocatalytic oxidization of various VOCs. In this work, a series of Fc-CHO/NU-X (X = 1, 2, 3, 4) were obtained through the ligand functionalization of reo -NH 2 -UiO-66 (denoted as NU) with ferrocenecarboxaldehyde (Fc-CHO) as the modifier. By altering the local charge distribution and inducing Fe-OH and cyclopentadienyl rings as new adsorption sites, Fc-CHO altered the adsorption behavior of both aromatic and oxygenated VOCs and consequently their degradation pathways. The introduction of electron-donating Fc-CHO enhanced the ligand to metal charge transfer (LMCT), accelerated the electron-hole separation and therefore promoted the effective formation of oxidative radicals, facilitating the effective oxidation of acetaldehyde. Direct charge transfer through p-p interaction enabled the ring-opening and deep oxidation of toluene. The degradation efficiencies of toluene and acetaldehyde increased from 25 % and 28 % (NU) to 80 % (Fc-CHO/NU-3) and 65 % (Fc-CHO/NU-2), respectively. Positive effects of Fc-CHO functionalization were also observed during the removal of acetaldehyde-toluene mixtures and the synergistic effect between acetaldehyde and toluene was revealed. This work provides new ideas and novel materials for the purification of in-door air pollutants.