Synergistic adsorption and visible-light catalytic degradation of RhB from recyclable 3D mesoporous graphitic carbon nitride/reduced graphene oxide aerogels

In this work, a series of mesoporous graphitic carbon nitride (MCN) nanometer materials, loaded onto the reduced graphene oxide aerogel (rGOA) with macroscopic three-dimensional (3D) porous structure, were prepared using reduction self-assembly method. The composite aerogel of MCN/rGOA hybrid (MCN/GO mass ratio of 3:9) showed the highest adsorption rate of 73.7% for removing rhodamine b (RhB) solution of 20 mg L−1, whereas the total effect of adsorption and visible-light catalysis reached 95.2% within 80 min. Meanwhile, the material also showed good stability, and the removal rate was still about 89% after repeating the experiments for five times. The material characterization was carried out using various techniques, which indicated that hybrid aerogels were successfully combined. The specific surface increases from 18 m2/g of MCN to 149 m2/g for MCN/rGOA hybrid. The hybrid aerogel not only has good adsorption effect, but also exhibits adequate photocatalysis. The composite firstly interacts with the RhB through π–π adsorption, and then, the photocatalysis is improved by increasing the electron transfer efficiency and inhibiting the electron–hole recombination for good conductivity. Through scavenger experiments, it is shown that h+ free radicals are the dominant oxidizer during photocatalytic degradation.