Flexible, scalable hierarchical graphene foam decorated with nickel layer for highly sensitive enzyme-free glucose sensing

Developing functional electrode materials for enzyme-free glucose electrochemical sensing is indispensable and challenging for rapid detection and instant diagnosis. Optimizing the microstructure of electrodes to enhance molecule accessibility, facilitate rapid mass transfer, and enlarge electrochemical active surface area is critical prerequisite for improving the electrochemical analytical performance. Herein, we develop a flexible graphene foam electrode with high conductivity and multilayer channel structure achieving efficient enzyme-free glucose sensor through one-step electrodeposition of nickel. The almost defect-free graphitic structure and layered multi-channel configuration enable the graphene foam to exhibit high conductivity, large specific surface area, and excellent mechanical performance. These properties result in efficient electron transmission and mass transfer, enabling the graphene foam to function as an excellent electrode substrate material in electrochemical sensors. Thus, the detecting electrode (Ni/GF) produced by electrodepositing nickel on graphene foam, demonstrates elevated sensitivity (1719.4 μA mM−1 cm−2), low limit of detection (0.2 μM), exceptional stability, and excellent flexibility for glucose detection. More importantly, the prepared electrode has been successfully applied to artificial sweat and tea, indicating its practical utility. The attractive analytical outcomes suggest that our layered multi-channel graphene foam has the potential to serve as a crucial foundational working electrode for designing efficient electrochemical sensor.