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The design of bimetallic tellurides that exhibit excellent electrochemical properties remains a huge challenge for high-performance supercapacitors. In the present study, tellurium is consolidated on CoNi2@rGO for the first time, to synthesize NiTe2-Co2Te2@rGO nanocomposite by using a facile hydrothermal method. As-prepared NiTe2-Co2Te2@rGO nanocomposite was characterized by EDS, TEM, FESEM, Raman, BET, XRD, and XPS techniques to prove the structural transformation. Upon the electrochemical characterization, NiTe2-Co2Te2@rGO has notably presented numerous active sites and enhanced contact sites with the electrolyte solution during the faradic reaction. The as-prepared nanocomposite reveals a specific capacity of 223.6 mAh g−1 in 1.0 M KOH at 1.0 A g-1. Besides, it could retain 89.3% stability after 3000 consecutive galvanostatic charge–discharge cycles at 1.0 A g−1 current density. The hybrid supercapacitor, fabricated by activated carbon as an anode site, and NiTe2-Co2Te2@rGO as a cathode site, presents a potential window of 1.60 V with an energy density of 51 Wh kg−1 and a power density of 800 W kg−1; this electrode is capable of lighting up two red LED lamps and a yellow LED lamp for 20 min, which is connected in parallel. The present work opens new avenues to design and fabrication of nanocomposite electrode materials in the field of supercapacitors.

A new electrochemical sensor based on NiO/Ni@C and poly(isonicotinic acid), PINA, is fabricated to determine an important chemotherapeutic drug, methotrexate (MTX). At first, a bare glassy carbon electrode (GCE) was modified by NiO/Ni@C; then, INA was electropolymerized at its surface. FT-IR, XRD, FE-SEM, EDS, elemental mapping, TEM, AFM, and BET techniques were used to characterize the nanomaterials. Following that, parameters affecting the sensor response, such as pH, amount of the electrocatalyst, electropolymerization cycles, and instrumental parameters, were optimized using cyclic voltammetry (CV) and differential pulse voltammetry (DPV). Under the optimized conditions, a linear range was obtained from 0.02 to 2.5 μM with a detection limit of 7.2 nM. Repeatability was obtained with a relative standard deviation (RSD) of 2.4%, and reproducibility was obtained with an RSD of 6.2%. Finally, the sensor was tested in the presence of potential interference compounds and human blood plasma with acceptable responses.

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