Atomic layer deposition of NiO-Coated CNT nanocomposites: Tailoring electrochemical properties for salivary lactate detection

Abstract

NiO-coated stacked-cut carbon nanotubes (NiO/SCCNT) nanocomposites were synthesized via atomic layer deposition (ALD), coating the CNT core walls with a shell of NiO at different thickness varying NiO ALD cycles (0, 50, 200, and 700). The as-prepared core–shell composite nanomaterials were applied as electrode materials for modifying screen-printed carbon electrodes (SPCE) for the non-enzymatic electrochemical detection of lactate (LA). Electrochemical tests performed by CV and EIS demonstrated the reduced charge transfer resistance in NiO(x)/CNT-SPCE compared to pristine CNT-SPCE configuration, and the pronounced dependence of electrochemical behavior on NiO coating thickness. Notably, the NiO/CNT composite with 200 ALD cycles exhibited superior electrochemical properties for the electrooxidation of lactate. The developed sensor showed high sensitivity to LA, (138.44 µA mM−1 cm−2 in the 0–4 mM range). The limit of detection (LOD) values stood at 0.067 mM (considering the signal-to-noise ratio of S/N=3). The sensor showcased several advantages including a conductive supporting carbon material, impressive sensitivity, selectivity, stability, and reproducibility, thereby enabling rapid and precise lactate quantification in salivary real samples.

Keywords: Atomic Layer Deposition, NiO-Coated, Nanocomposites, Electrochemical Properties