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• Facile preparation of Copper nanostructures on cost-effective pencil graphite substrate. • Copper-silver bimetallic nanostructure preparation by galvanic replacement reaction. • Electrocatalytic studies of dopamine oxidation. • High sensitivity and selectivity for dopamine sensing with very low LOD. • Practical feasibility studies using dopamine hydrochloride injection and urine samples. Herein we report preparation of copper-silver bimetallic nanostructures with excellent electrocatalytic properties. Copper nanostructures were formed by template electrodeposition method while bimetallic nanostructures were prepared by galvanic replacement of copper with silver. Electrocatalytic activity of these nanocatalysts were demonstrated using electroanalysis of dopamine as model analyte. A maximum sensitivity of 1.56 μA/μM/cm2 and a lower limit of detection of 26 nM together with good recovery in real sample analysis provided the practical feasibility of the sensor. In summary, this work demonstrates a facile route for the fabrication of cost-effective bimetallic nanoelectrocatalysts under ambient conditions within a short duration of time. [ABSTRACT FROM AUTHOR]

• For the first time a combined electrode system (TyB-GGG) was introduced. • Good electrocatalytic performance of TyB-GGG towards the analyte determination. • Present method replaces the reference electrode and also liquid junction potential. • TyB-GGG successfully employed for the analysis of Hydrochlorothiazide (HTZ). A Trypan Blue modified combined pencil graphite electrode system (TyB-GGG) has been employed for the electrochemical investigation of Hydrochlorothiazide (HTZ). The linear calibration curves were obtained in the concentration range of 0.5–7 µM (for DPV) and 0.1–5 µM (for SWV), respectively. The detection limits were found to be 0.1327 µM and 0.0320 µM, respectively. The electrodes resistance has been studied using electrochemical impedance spectroscopy (EIS). The modified electrode TyB-GGG has been successfully employed for the determination of HTZ present in pharmaceutical sample. [ABSTRACT FROM AUTHOR]