Multifunctional electrodes based on brochantite/malachite/polyaniline on Ni foam for the fabrication of binder-free supercapacitors and pyrimethanil/carbendazim fungicide electrochemical sensors

In this work, multifunctional electrode materials based on copper-based compounds and polyaniline were applied for binder-free supercapacitors and pyrimethanil/carbendazim fungicide sensors for the first time. Brochantite and malachite were synthesized on Ni foam via a one-step solvothermal method. Polyaniline (PANI) was electrochemically polymerized as inner and outer layers. PANI as the inner layer for the brochantite/malachite@Ni foam was found to enhance conductivity and cycling stability. The composite electrodes synergistically provided a specific capacitance as high as 737 F g−1 and a capacitance retention of 83.15 % after 10,000 cycles, which are much better than each of its parent compounds. During the in-situ fabrication of supercapacitor electrode on Ni foam, the powder form of brochantite/malachite mixture was also recovered from the reaction mixture, which was then used to prepare the composite electrodes with PANI. These fabricated electrodes demonstrated superb electrochemical sensing activity for the detection of pyrimethanil and carbendazim fungicides, giving the limits of detection of 29 and 10 nM, respectively. These fungicides were successfully determined in fruits, vegetables, and water sources, yielding satisfactory recovery between 99.8 and 107.5 %. The high-performance electrochemical electrodes based on copper-based compounds developed in this study hold significant potential for a variety of electrochemical applications.