Facile fabrication of three-dimensional nanofibrous foams of cellulose@g-C₃N₄@Cu₂O with superior visible-light photocatalytic performance

In this work, a unique three-dimensional nanofibrous foam of cellulose@g-C₃N₄@Cu₂O was prepared via electrospinning followed by a foaming process. A cellulose solution in DMAc/LiCl containing g-C₃N₄ and CuSO₄ was applied for electrospinning, while aqueous alkali was used as the coagulation bath. The solidification of electrospun cellulose/g-C₃N₄ nanofibers would be accompanied with in-situ formation of Cu(OH)₂ nanoparticles. Interestingly, the hydrogen gas (H₂) generated from NaBH₄ could transform the two-dimensional membrane into a three-dimensional foam, leading to the increased specific surface area and porosity of the material. Meanwhile, the Cu(OH)₂ nanoparticles attached on the electrospun nanofibers were reduced to Cu₂O to form a p-n heterostructure between Cu₂O and g-C₃N₄. The as-prepared cellulose@g-C₃N₄@Cu₂O foam exhibited a high degradation efficiency (99.5 %) for the dye of Congo Red under visible light radiation. And ·O^2- was discovered to be the dominant reactive species responsive for dye degradation. Moreover, the cellulose@g-C₃N₄@Cu₂O could maintain its initial degradation efficiency even after seven cycles of reuse, suggesting the excellent stability and cycling performance.