All-solid-state nitrate selective electrode with graphene/tetrathiafulvalene nanocomposite as high redox and double layer capacitance solid contact

Electrodes with graphene-tetrathiafulvalene nanocomposite intermediate layer between a glassy carbon disc electrode and an ionophore-doped solvent polymeric membrane have been made as a new type of all-solid-state ion-selective electrodes. The proposed interlayers prepared in a quite simple drop casting method exhibited a high redox and double layer capacitance resulting from the use of both, tetrathiafulvalene (TTF/TTF+) as redox-reaction based transducer and graphene (GR) as carbon material with a large surface area forming high electrical double layer at the ion-selective membrane and the solid contact interface. The influence of the used solid-contact composition on metrological parameters of studied electrodes was characterized by electrochemical measurements. The graphene-TTF/TTF+ solid contact layer capacitance determined applying a current 5 nA was 1.18 mF and potential drift was only 4.26 mu V s(-1). The GR-TTF/TTF+-modified electrodes exhibited a good Nernstian response with a slope of -59.14 mV/dec in the range from 10(-6) to 10(-1) M nitrate ions. (C) 2016 Elsevier Ltd. All rights reserved.