Facile fabrication of atomically dispersed iron through the nanoconfined environment for phenol hydroxylation

Diphenols constitute a class of chemical compounds with diverse applications, and the contemporary method for diphenol synthesis involves the hydroxylation of phenol with a catalyst. The catalysts with Fe sites serve as the active centers for the phenol hydroxylation reaction, with their activity being influenced by both the quantity of Fe sites and their degree of dispersion. However, it is still difficult to prepare highly dispersed Fe sites catalysts at the atomic level by facile methods. Here, we provide a convenient methodology to prepare Fe single-atom catalyst (SAC) by utilizing the nanoconfined environment between the template and silica walls in template-occupied mesoporous silica KIT-6. Through solid-phase milling and calcination, Fe precursors were introduced into the nanoconfined environment to form the Fe-O-Si structure. In the phenol hydroxylation reaction, Fe SAC activity was significantly increased compared to the comparison sample prepared without the nanoconfined environment as well as various reported catalysts.