Electrochemical performance of nickel-modified glassy carbon electrodes for glucose oxidation: ionic liquid vs. aqueous deposition methods

Abstract This study examines the electrochemical performance of nickel-modified glassy carbon electrodes (GCEs) deposited from ionic liquid, typically ethaline, (Ni IL /GC) and aqueous solutions (Ni AQ /GC) for glucose oxidation. SEM analysis shows a fine-grained, nanostructured morphology with microcracks in the ionic liquid-deposited film. EDX confirms high nickel content (44.6%) and surface oxidation (6.8%). XRD indicates face-centered cubic nickel and nickel oxides with an average nanoparticle size of 33 nm. Cyclic voltammetry reveals Ni IL /GC exhibits superior electron transfer and catalytic activity towards glucose oxidation, with sharper oxidation peaks and a 100 mV cathodic shift compared to Ni AQ /GC. Nyquist plots show lower impedance for Ni IL /GC, signifying improved charge transfer efficiency. Tafel analysis shows a lower slope (30 mV/decade) for Ni IL /GC, indicating faster glucose oxidation kinetics. The Ni IL /GC electrode also demonstrates superior stability with minimal degradation during long-term cycling. These results highlight Ni IL /GC’s enhanced electrochemical properties and stability, making it promising for glucose sensing and electrocatalytic applications.