Integrating NiFe bimetal sites into a conjugated microporous polymer for boosting photocatalytic selective aromatic alcohol oxidation

Abstract

Photocatalytic selective oxidation of aromatic alcohols to aldehydes under mild conditions is of great significance for green and sustainable development, and design of photocatalysts with high efficiency is an interesting topic. Herein, we present a new conjugated microporous polymer photocatalyst named NiFe-CMP, composed of Ni-porphyrin and Fe-bipyridyl units, for efficient photocatalytic oxidation of aromatic alcohols. The porous structure of NiFe-CMP provides numerous absorption sites and exposes catalytically active centres, enhancing the reaction kinetics. Experimental and theoretical analyses indicate that the incorporation of Fe and Ni dual-metal sites not only enhances the dissociation of excitons into free charge carriers by regulating the electronic structures, but also reduces the reaction energy barrier for the formation of *O₂ intermediates, thus promoting the massive production of ˙O₂⁻ active species. Impressively, NiFe-CMP manifests excellent catalytic performance, achieving a 96.2% conversion rate for the oxidation of benzyl alcohol to benzaldehyde under 4 hours of visible light radiation, over approximately 17 times higher than that of the pristine CMP. Besides, NiFe-CMP exhibits high recyclability and displays an excellent adaptability towards various aromatic alcohols. This work further advances the rational design of efficient photocatalysts for selective aromatic alcohol oxidation.