Effect of Al2O3 thickness on performance of Al2O3/CNTS in the electrochemical sensing of di- hydroxybenzene isomers

This study aimed at analyzing the effect of thickness of dielectric Al2O3 coatings deposited onto the conductive stacked- cup carbon nanotubes (SCCNTs) on their electrochemical properties. Atomic layer deposition (ALD) technique was used to deposit well-controlled variable thicknesses of Al2O3 on the SCCNTs substrates. Transmission electron microscopy (TEM)), high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM) and the energy dispersive X-ray spectroscopy (EDX) elemental-mappings clearly demonstrated the successful conformal deposition of Al2O3 with different thicknesses onto the inner and outer walls of the carbon nanotubes. The SCCNT/Al2O3(X) modified screen printed electrodes (SPEs) were used towards the simultaneous determination of di-hydroxybenzene isomers, hydroquinone (HQ) and catechol (CC). SCCNT/Al2O3 nanostructures resulted highly active towards di-hydroxybenzene isomers and both sensitivity and selectivity of the developed electrochemical sensors are strongly dependent on the thickness of the Al2O3 layer. The remarkable performance of the as-synthesized SCCNT/Al2O3 heterostructures can be attributed to the conformal coating of the Al2O3 shell layer, the optimized thickness of the Al2O3 film and the CNT conductive substrate. © 2019 IEEE.