Highly compressible ultra-light 3D cellulose/graphene/carbon nitride aerogel for enhanced photocatalytic activity

The fabrication of 3D compressible holey structures with large specific surface area, easy recyclability, and abundant catalytic active sites to enhance the ability of photocatalytic performance under visible light has been attracted wide attention. In this work, 3D compressible CNF/rGO/g-C3N4 aerogels have been prepared through a facile bidirectional freeze-drying process followed by thermal reduction. The rGO not only served as the support layer but also worked as the electron transfer channel to accelerate electron-hole pair separation and transport. Moreover, the dispersed CNFs also acted as supports and thus might enhance the mechanical strength of rGO/gC3N4 aerogel. By tuning the g-C3N4 mass ratio, the photocatalytic degradation performance of Rhodamine B (RhB) and the production of H2 of the CNF/rGO/g-C3N4 aerogels were estimated. The degradation rate of RhB reached to 87.3 % under 300 W Xe lamp visible light with a 420 nm cutoff filter. And the prepared aerogels could be conveniently reused, and maintained considerable stability and excellent recycling activity in cycling tests. In addition, the optimum H2 yield of CNFs/rGO/g-C3N4 could reach up to 417.5 mu mol h-1 g-1, which was 1.7 times higher than that of bulk g-C3N4 (244.5 mu mol h-1 g-1). Furthermore, these aerogels also exhibited good mechanical properties, the height retention of CNF/rGO/g-C3N4 aerogels was still over 89 % after 100 cycles of compression at strain of 40 %. The possible photocatalytic mechanism was studied with active groups and degradation routes by EPR experiments. The reactive species of h+, center dot O2-, and center dot OH showed strong oxidation ability, leading to the oxidation of organic pollutants. This work exhibits a practical strategy to construct 3D compressible CNF/rGO/g-C3N4 aerogels with outstanding mechanical property and outstanding photocatalytic performance for organic wastewater and energy production.