Green, low-cost synthesis of photoluminescent carbon dots by hydrothermal treatment of willow bark and their application as an effective photocatalyst for fabricating Au nanoparticles–reduced graphene oxide nanocomposites for glucose detection

In this study, we demonstrate that hydrothermal carbonization of low-cost wastes of willow bark leads to water-soluble, photoluminescent carbon dots (CDs) with diameters ranging from 1 to 4 nm and a quantum yield of approximately 6.0%. We further demonstrate the proof of concept that such CDs can be used as an effective photocatalyst for the simultaneous reduction of Au(III) complex and graphene oxide to form Au nanoparticles decorated reduced graphene oxide (AuNPs–rGO) nanocomposites by UV irradiation of a mixture of GO and HAuCl4 aqueous solution in the presence of CDs. It is found that the resultant AuNPs–rGO nanocomposites exhibit notable catalytic performance for H2O2 reduction and oxidation. Furthermore, we fabricate a glucose biosensor by immobilizing glucose oxidase on the AuNPs–rGO-modified glassy carbon electrode for glucose detection. The linear response range and detection limit are estimated to be from 2 mM to 18 mM (r: 0.995) and 45 μM, respectively. The application of this glucose sensor in human blood serum has also been demonstrated successfully.