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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 10-10 M, a low detection limit of 10 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.
PMID: 31711668 [PubMed - as supplied by publisher]