Separate-free BiPO4/graphene aerogel with 3D network structure for efficient photocatalytic mineralization by adsorption enrichment and photocatalytic degradation

The energy-saving and thorough purification of industrial phenol, methylene blue (MB) and formaldehyde at room temperature causes great attention in the environment field. This manuscript aims to combine adsorption-enrichment and photocatalytic degradation pollutants using three-dimensional network structure BiPO4/graphene aerogel (GA), which is synthesized by one-step hydrothermal method. BiPO4 nanorods are distributed and anchored uniformly into the three-dimensional porous GA structure. In the static experiment, 70%-BiPO4/GA composites could degrade 50.67% phenol, which is greater than that of pure BiPO4 powder (31.99%). In the dynamic system, the degradation content of MB for 70%-BiPO4/GA composites is 96.23% and the degradation rate is 2.03 times of that of pure BiPO4 powder. Degradation content of gas phase formaldehyde is 26.4% in 2 h, which is 1.66 times than that of pure BiPO4, owing to the adsorption enrichment-synergistic photocatalytic degradation. High aspect ratio BiPO4 with thinnest graphene layers (about 4 layers) favors to lower the valence band maximum and enhances the oxidation ability. The mainly active species are superoxide and holes demonstrated by trapping experiment. Construction of BiPO4/GA composites solves the problem of GA adsorption saturation and poor photocatalytic activity of BiPO4. The results would serve as a theoretical basis and technical support for the pollutant purification field.