Preparation of ultrathin defect-free graphene sheets from graphite via fluidic delamination for solid-contact ion-to-electron transducers in potentiometric sensors

• Published in: Journal of colloid and interface science 2020-02, Vol.560, p.817-824
• Main Authors: Park, Hong Jun, Jeong, Jae-Min, Yoon, Jo Hee, Son, Seon Gyu, Kim, Yeong Kyun, Kim, Do Hyun, Lee, Kyoung G., Choi, Bong Gill
• Format: Article
• Language: English
• Subjects: Exfoliation; Graphene; Ion sensor; Potentiometry; Solid contact
• ISSN: 0021-9797; 1095-7103
• DOI: 10.1016/j.jcis.2019.11.001

Ultrathin and defect-free graphene sheets obtained by a fluid dynamics-induced exfoliation method show excellent performances of solid contact ion-to-electron transducer in potentiometric sensors with a Nernstian sensitivity, fast response time, potential stability, good repeatability, and excellent long-term stability. [Display omitted] In this study, ultrathin and defect-free graphene (Gr) sheets were prepared through a fluid dynamics–induced shear exfoliation method using graphite. The high hydrophobicity and surface area of Gr make it attractive as a solid-contact ion-to-electron transducer for potentiometric K+ sensors, in which the electrodes are fabricated through a screen-printing process. The electrochemical characterization demonstrates that Gr solid contact results in a high double-layer capacitance, potential stability, and strong resistance against water layer, gases, and light. The Gr-based K+ sensors showed a Nernstian slope of 53.53 mV/log[K+] within a linear concentration range of 10−1–10−4 M, a low detection limit of 10−4.28 M, a fast response time of ~8 s, good repeatability, and excellent long-term stability. Moreover, the Gr-based K+ sensors provided accurate ion concentrations in actual samples of human sweat and sports drinks.