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 ·O2- 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.