A Promoted Charge Separation/Transfer System from Cu Single Atoms and C3N4 Layers for Efficient Photocatalysis

Establishing highly effective charge transfer channels in carbon nitride (C3 N4 ) for enhancing its photocatalytic activity is still a challenging issue. Herein, for the first time, the engineering of C3 N4 layers with single-atom Cu bonded with compositional N (CuNx ) is demonstrated to address this challenge. The CuNx is formed by intercalation of chlorophyll sodium copper salt into a melamine-based supramolecular precursor followed by controlled pyrolysis. Two groups of CuNx are identified: in one group each of Cu atoms is bonded with three in-plane N atoms, while in the other group each of Cu atoms is bonded with four N atoms of two neighboring C3 N4 layers, thus forming both in-plane and interlayer charge transfer channels. Importantly, ultrafast spectroscopy has further proved that CuNx can greatly improve in-plane and interlayer separation/transfer of charge carriers and in turn boost the photocatalytic efficiency. Consequently, the catalyst exhibits a superior visible-light photocatalytic hydrogen production rate (≈212 µmol h-1 /0.02 g catalyst), 30 times higher than that of bulk C3 N4 . Moreover, it leads to an outstanding conversion rate (92.3%) and selectivity (99.9%) for the oxidation of benzene under visible light.