Deciphering the high-carbonization-temperature triggered enzymatic activity of wool-derived N, S-co-doped carbon nanosheets

It is well-established that high carbonization temperature will trigger the enzyme-like activity of carbon-based materials. However, the catalytic mechanism is still ambiguous, which hinders the further rational design of nanomaterials as enzyme mimics. Hereby, N, S-rich carbonized wool nanosheets (CWs) were synthesized at different pyrolysis temperatures. As expected, only CWs treated with high-temperature possess intrinsic oxidase-and peroxidase-like activities. Meanwhile, density functional theory (DFT) calculations demonstrate that graphitic nitrogen and the co-existence of nitrogen and sulfur in the carbon matrix serve as the active sites for the enzyme-like process. More importantly, combining theoretical calculations and experimental observations, the high-temperature triggered catalytic mechanism can be ascribed to the fact that an appropriate high-temperature maximizes the graphitization degree to a certain extent, at which most of the catalytic active sites are well retained rather than evaporating. Moreover, coupling with excellent photothermal conversion efficiency and catalytic performance, CWs can be applied to photothermal-catalytic cancer therapy under near-infrared region (NIR) light irradiation. We believe this work will contribute to understanding the catalytic mechanism of carbon-based nanozymes and promote the development of new biomedical and pharmaceutical applications.(c) 2023 Published by Elsevier B.V. on behalf of Chinese Chemical Society and Institute of Materia Medica, Chinese Academy of Medical Sciences.