Mechanochemical synthesis of Mg doped ZnO/CuO heterojunction composite-based electrode for electrochemical sensing

The influence of Mg doping and the impact of heterointerface growth mechanism of mechanochemically synthesized Mg-doped ZnO/CuO (MZC) heterojunction composite as electrode material for electrochemical sensing applications have been investigated. Thin-film composite electrode composed of bulk Mg doped ZnO/CuO nanocomposite deposited on ITO glass substrates using spin coating were fabricated. Structural analysis revealed that the hexagonal wurzite features of ZnO was preserved with Mg doping, and no new phases were developed. The MZC composite consists of prominent wurzite ZnO peaks along with peaks correspond to cubic monoclinic CuO. A significant reduction of D is estimated on the analyzed phases. his finding agrees with the field emission scanning electron microscopy (FESEM) morphologies of ultra-small interconnected MZ and CuO particles that were reduced and had high defect levels due to the mechanochemical effect. Energy-dispersive X-ray spectroscopy (EDX) analysis confirmed the complete transformation of the starting materials. X-ray photoelectron spectroscopy (XPS) analysis confirmed the existence of ZnO and CuO compositions, as well as a Mg phase in the composite.  Cyclic voltammetry analysis revealed an improved peak current and narrower anodic-cathodic potential separation from 233 μA of basic ZnO (Z) electrode to 245 μA on the Mg-doped ZnO/CuO composite electrodes (MZC) indicating higher sensitivity and a much higher charge transfer rate, respectively. The findings provide promising insights into Mg-doped ZnO/CuO bulk heterojunction nanocomposite systems and their potential for electrochemical sensing applications.