Excitation-dependent carbon dots powders based on dehydration condensation by microwave–hydrothermal method

A green and economical microwave–hydrothermal method is employed to prepare carbon dots (CDs) that low-cost DL-malic acid serves as the carbon source and the formamide serves simultaneously as the pyrolysis solvent and carbon source. In the reaction process, neither assistant catalytic treatment nor further surface modification is necessary. We obtain better disperse CDs powders whose quantum yield reaches 25% as well as explain the dehydration condensation reaction mechanism based on the analysis by XPS and FTIR data. The luminescent properties are investigated in detail, and the results reveal that the excitation-dependent feature of as-prepared CDs has the potential for anti-counterfeiting mark and luminescence picture field.