A magnetic field-directed self-assembly solid contact for construction of an all-solid-state polymeric membrane...

A magnetic field-directed self-assembly solid contact has been proposed for developing an all-solid-state polymeric membrane Ca²⁺-selective electrode. The solid contact is prepared by physically adsorbing magnetic graphene powder on a magnetic gold electrode under the direction of the magnetic field. The proposed method for preparing solid contact avoids using the aqueous solutions and is simple, fast and general as compared to the multilayer drop-casting and electrodeposition methods. The all-solid-state Ca²⁺-selective electrode based on magnetic graphene as solid contact shows a stable potential response in the linear range of 1.0 × 10^-6-1.0 × 10^-3 M with a slope of 28.2 mV/decade, and the detection limit is about 4.0 × 10^-7 M. Additionally, the magnetic graphene-based electrode shows a comparable potential stability performance to other graphene-based all-solid-state ion-selective electrodes, such as reduced undesirable water layer and insensitive to the interferences of O₂, CO₂ and light. This work provides a favorable way to prepare solid contact for use in the field of all-solid-state ion-selective electrodes.