Protein-directed synthesis of bifunctional adsorbent-catalytic hemin-graphene nanosheets for highly efficient removal of dye pollutants via synergistic adsorption and degradation

Herein, for the first time, we report a "green", one-pot reduction/decoration method for the synthesis of bifunctional adsorbent-catalytic hemingraphene nanosheets by using a common available protein (bovine serum albumin, BSA) as both a reductant and a stabilizer. Our prepared nanosheets are highly stable and possess intrinsic peroxidase-like catalytic activity due to the decoration of BSA and hemin. Furthermore, benefiting from the combined advantages of graphene and BSA, these nanosheets are able to efficiently adsorb dye pollutants from aqueous solution. More importantly, due to their adsorption and catalytic ability, these adsorbent-catalytic nanosheets can be applied to highly efficient dye removal via synergistic adsorption and degradation. Specifically, our catalysts can easily bring organic dyes to their surface by adsorption, and then activate H₂O₂ to generate hydroxyl radicals, leading to the degradation of the dyes. Such catalytic mechanism of our as-prepared nanosheets was analogous to that of natural enzymes, in which the extremely high catalytic efficiency is largely dependent upon their ability to bring substrates in close proximity to the active sites of enzymes. Our finding may open new potential applications of hemin-graphene hybrid nanosheets in environmental chemistry, biotechnology, and medicine.