A freestanding all-solid-state polymeric membrane Cu2+-selective electrode based on three-dimensional graphene sponge.

A novel freestanding all-solid-state polymeric membrane Cu2+-selective electrode (Cu2+-ISE) is proposed based on three-dimensional graphene sponge (3D GS). The 3D GS electrode has been characterized by cyclic voltammetry, electrochemical impedance spectroscopy, and contact angle measurements. Experiments show that 3D GS possesses a large electrical double layer capacitance, good conductivity, and high hydrophobicity. Based on these superior properties, 3D GS has been applied as both electrode substrate and solid contact for construction of a freestanding all-solid-state polymeric membrane Cu2+-ISE. The 3D GS-based Cu2+-ISE shows a good Nernstian response ranging from 1.0 × 10-8 to 7.9 × 10-4 M with a low detection limit of 2.5 × 10-9 M. Moreover, the proposed Cu2+-ISE exhibits a stable potential response with a reduced water layer at the sensing membrane/3D GS interface and is not affected by interferences from light, O2 and CO2.