Direct-laser-writing of three-dimensional porous graphene frameworks on indium-tin oxide for sensitive electrochemical biosensing.

The fabrication of graphene electrode with three-dimensional (3D) porous architecture would be highly desirable for electrochemical (bio-)sensing. Direct-laser-writing (DLW) on polyimide sheet has been recognized as an advance approach to pattern 3D porous graphene frameworks (3DPGFs)-based electrode. Herein, taking advantages of this straightforward and cost-effective DLW technique, we demonstrated the scalable and robust fabrication of a new type of 3DPGFs-based electrode patterned on the surface of indium-tin oxide (ITO) glass, denoted as 3DPGF@ITO. In this study, polyimide layer was synthesized on ITO glass surface not only to act as a sacrificial precursor for the in situ growth of 3DPGFs, but also to serve as a passivation layer for the effective separation of 3DPGFs working area and ITO contact pad. Importantly, the laser-induced 3DPGFs on ITO surface exhibit a 3D hierarchical and macroporous architecture consisting of interconnected multi-layered graphene sheets with large surface area and abundant edge-plane-like defective sites. These appealing features render the proposed 3DPGF@ITO electrode with marked improvement in electrochemical performance over traditional commercial electrodes. Finally, the developed 3DPGF@ITO electrode was successfully applied as a working electrode to selectively detect three important biospecies, namely, ascorbic acid, dopamine, and uric acid, in their ternary mixture with a high resolution of oxidation potentials. Thus, we envision that the 3DPGF@ITO electrode will open highly promising perspectives for the development of sensitive electrode-based (bio-)sensors.