Enhanced photocatalytic phenol production from benzene on polymers with coordinatively unsaturated Fe centers

The photocatalytic hydroxylation of benzene to phenol using low-cost Fe-based materials is of great significance but remains a great challenge for the conversion of benzene in an efficient manner. Here we report a novel method to construct polymeric Fe-BTC-350 with highly dispersed coordinatively unsaturated (CUS) Fe centers by a simple pyrolysis of iron benzene tricarboxylic acid (Fe-BTC) coordination polymer. The CUS Fe centers in Fe-BTC-350 function as Lewis acid sites to accept both electrons and hydroxyl radicals, thus enhancing photocatalytic phenol generation. An optimal phenol yield of 22.7 % has been achieved over optimized Fe-BTC-350 which is 2.8 times that of the Fe-BTC. No evident decay in the activity was found after 4 cycles of consecutive reactions, indicating the robust stability of the photocatalyst. It is expected that the construction of CUS transition metal centers can also be utilized for other photocatalytic radical reactions.