The Effect of Carbon Nanotubes Solid Contact Dispersing Agent on the Parameters of Resulting Potentiometric Sensors

Carbon nanotubes are important nanostructured material for different applications, including electrochemical sensors [1,2].   Among other advantages related to electrochemical properties of carbon nanotubes, they can be applied in simple procedure, resulting in electronically conducting layers. For sensor purposes (e.g. ion-selective electrodes, field effect-transistors) carbon nanotubes (CNTs) suspension (called ink) can be simply drop cast or spray coated on different substrates. However, to prepare a useful and stable CNTs suspension in water application of stabilizing agent is necessary. This agent is usually an ion or polymer that spontaneously absorb on CNTs – e.g. sodium dodecylsulfate, sodium dodecylbenzene sulfate or carboxymethyl celulose [1-4]. As a consequence this substance is present also in obtained CNTs layer and potentially can affect their performance.

In this study potassium selective electrodes with CNTs solid contact were prepared. The CNTs transducer layers were obtained by drop casting, using suspensions stabilized with different agents – surafctants as well as complexing ligands. The effect of CNTs suspension stabilizing agent on performance of potentiometric sensors - analytical parameters (sensitivity, selectivity, detection limit) as well as stability of potentiometric responses in time were studied. Potentiometric (open circuit), chronopotentiometric and impedance studies have confirmed that the nature of  dispersing agent used as well as its amount used affects performance of the sensor. Dispersing agent used can partition into sensor layers – e.g. ion-selective membrane - significantly altering their properties. Herein obtained results are potentially important for all applications in which CNTs layer are fabricated using stable dispersion of nanomaterial. 

REFERENCES

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2. F. X. Rius - Ruiz, G. A. Crespo, D. Bejarano - Nosas, P. Blondeau, J. Riu, F. X. Rius, Anal. Chem. 2011, 83, 8810. 

3. K. Melzer, A. M. Münzer, E. Jaworska, K. Maksymiuk, A. Michalska, G. Scarpa, Analyst 2014, 139, 4947

4. E. Jaworska, M. Schmidt, G. Scarpa, K. Maksymiuk, A. Michalska Analyst 2014, 139, 6010.