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 (C3N4) for enhancing its photocatalytic activity is still a challenging issue. Herein, for the first time, the engineering of C3N4 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 C3N4 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 C3N4. Moreover, it leads to an outstanding conversion rate (92.3%) and selectivity (99.9%) for the oxidation of benzene under visible light. Based on a chlorophyll sodium copper salt (CSC) in situ intercalated supramolecular and following pyrolysis procedure, Cu single atoms (CuNx) are anchored in and between C3N4 layers, which opens both in‐plane and interlayer charge‐transfer channels. Therefore, the hydrogen evolution ability is significantly improved (212 µmol h−1, catalyst 20 mg). It also shows impressive conversion and selectivity for the oxidation of benzene.