Biomass-Derived Hierarchical Nanoporous Carbon with Rich Functional Groups for Direct-Electron-Transfer-Based Glucose Sensing

Glucose oxidase (GOD) is immobilized, for the first time, on a hierarchical nanoporous carbon (HNC) with rich functional groups by carbonizing a biomass derivation extracted from green tree leaves on a nanostructured CaCO3 template at high temperature, which exhibits fast electrooxidation for glucose and direct electron transfer (DET) when using the GOD catalyst on the new carbon support, delivering 6 and 12 times higher kinetic currents for electrochemical glucose sensing without additional electron mediators compared to commercial activated carbon and conventional hierarchical nanoporous carbon, respectively. The appearance of multiple surface heteroatom functional groups, such as amines, amides and thiols, which remain when the biomass is carbonized, rather than surface hydrophilicity, is associated with the appearance of facile direct electrochemistry processes, thus offering a new insight into DET for inexpensive and highly sensitive enzymatic sensors.