Adsorption and visible-light photocatalytic degradation of organic pollutants by functionalized biochar: Role of iodine doping and reactive species.

Here we developed the functionalized biochar as low-cost and heavy metal-free photocatalysts via a facile iodine doping method, which exhibit efficient adsorption and visible-light-driven photocatalytic degradation of representative organic pollutants, phenol and tetracycline. On one hand, iodine doping elevates the adsorption via creating extra pores, e.g., the adsorbed amounts of phenol by iodine-doped WSP and OSR biochar are increased by 161.8% and 146.3%, respectively, which in turn facilitates the photocatalytic oxidation of the adsorbed pollutants. On the other hand, iodine doping leads to the strong photo-induced excitation and remarkably reduced charge carrier transfer resistance, boosting the photocatalytic activity of iodine-doped biochar by more than 20 orders towards organic pollutants (e.g., phenol) degradation. The systematic analysis of reactive species reveals the active roles of O, HO, O, OH, electrons, and holes in photocatalytic process and identifies O to be the major contributor. This work affords a facile approach to generating porous and visible-light-driven photocatalyst from biomass for efficient adsorbing and degrading organic pollutants, opening up an avenue to turn biowaste into biomaterials for sustainable environmental remediation.