A low-potential, H2O2-assisted electrodeposition of cobalt oxide/hydroxide nanostructures onto vertically-aligned multi-walled carbon nanotube arrays for glucose sensing

A novel nanocomposite was synthesized using a cathodic, low-potential, electrochemical reduction of H2O2 to homogeneously deposit cobalt oxide/hydroxide (denoted as CoOx·nH2O) nanostructures onto vertically well-aligned multi-walled carbon nanotube arrays (MWCNTs), while the MWCNTs were prepared by catalytic chemical vapor deposition (CVD) on a tantalum (Ta) substrate. The CoOx·nH2O–MWCNTs nanocomposite exhibits much higher electrocatalytic activity towards glucose (Glc) after modification with CoOx·nH2O than before. This non-enzymatic Glc sensor has a high sensitivity (162.8 μA mM−1 cm−2), fast response time (<4 s) and low detection limit (2.0 μM at signal/noise ratio = 3), and a linear dynamic range up to 4.5 mM. The sensor output is stable over 30 days and unaffected by common interferents that co-exist with Glc in analytical samples; it is also resistant to chloride poisoning. These features make the CoOx·nH2O–MWCNTs nanocomposite a promising electrode material for non-enzymatic Glc sensing in routine analysis.

► We successfully synthesized CoOx·nH2O–MWCNTs nanocomposites using a cathodic electrochemical reduction of H2O2 to deposit cobalt oxide/hydroxide nanostructures onto vertically well-aligned MWCNTs arrays.
► This is an enzyme-free sensor.
► Under optimal detection conditions, the sensor showed a good-enough sensitivity of 162.8 μA mM−1 cm−2, a low detection limit of 2.0 μM (S/N = 3) and a fast response of less than 4 s within the linear range of up to 4.5 mM.
► Other advantages of the sensor for Glc measurements include high insensitivity to common interferences, long-term stability, reproducibility and resistance to chloride poisoning without additional outer membrance like Nafion. Therefor it is useful for routine Glc analysis.
► The novel nanocomposite material with good mechanical strength and high conductivity can be planted into microchannels to conduct sophisticated lab-on-a-chip Glc detection.