Graphitic carbon nitride/Cu2O heterojunctions: Preparation, characterization, and enhanced photocatalytic activity under visible light

•A hydrothermal method was used to prepare C3N4–Cu2O heterojunction.•The resulting heterojunction possesses broader absorption in the visible region.•The material owns a high visible light activity and stability for dye degradation.

As a metal-free semiconductor material, graphitic carbon nitride (C3N4), the high recombination rate of photogenerated charges and insufficient sunlight absorption limit its solar-based photocatalytic activity. Here, we reported the heterojunctions of C3N4–Cu2O with a p–n junction structure, which was synthesized by a hydrothermal method. The HR-TEM result revealed an intimate interface between C3N4 and Cu2O in the heterojunction, and UV–vis diffuse reflection spectra showed their extended spectral response in the visible region compared with pure C3N4. These excellent structural and spectral properties, as well as p–n junction structures, endowed the C3N4–Cu2O heterojunctions with enhanced photocatalytic activities. The possible photocatalytic mechanism that photogenerated holes as the mainly oxidant species in photocatalysis was proposed base on the trapping experiments.

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