Highly stable and redox active nano copper species stabilized functionalized-multiwalled carbon nanotube/chitosan modified electrode for efficient hydrogen peroxide detection

摘要

A highly redox active and stable nano copper species immobilized functionalized-multiwalled carbon nanotube (f-MWCNT)+chitosan (CHIT) film coated glassy carbon electrode (Cuf-MWCNT+CHIT/GCE) was fabricated using a new preparation procedure, different from the conventional Cu ~(2+)+MWCNT+CHIT bulk electro-codeposition coupled glassy carbon surface activation method, for selective and sensitive amperometric estimation of H _2O _2 at -100mV vs Ag/AgCl in physiological solution. Several copper modified film electrodes with nano copper species immobilized into films made of single component or different combinations of CNT and CHIT (i.e., Cuf-MWCNT+CHIT/GCE, CuSWCNT+CHIT/GCE, Cuf-MWCNT/GCE, CuMWCNT/GCE, CuCHIT/GCE and Cu/GCE) were characterized by cyclic voltammetry in a blank pH 7 phosphate buffer solution (PBS), and only the Cuf-MWCNT+CHIT/GCE showed well-defined redox peak with an half-wave potential (E _(1/2)) of -85mV vs Ag/AgCl for the matrix immobilized Cu ~(2+)/Cu ~+ redox species with very good film stability and pronounced leaching resistance to copper. Transmission electron microscopy, scanning electron microscopy, energy dispersive X-ray analysis, X-ray photoelectron spectroscopy were used to give a complete characterization of the Cuf-MWCNT+CHIT/GCE. Effect of potential scan rate and pH on the redox response of the Cuf-MWCNT+CHIT/GCE was studied to probe the mechanism of Cu ~(2+)/Cu ~+ electron transfer process. The Cuf-MWCNT+CHIT/GC electrode showed effective electrocatalytic reduction of H _2O _2 in pH 7 PBS. Amperometric i-t method of H _2O _2 detection yielded a calibration plot linear up to 125μM with a current sensitivity of 0.463AM ~(-1)cm ~(-2). The newly developed Cuf-MWCNT+CHIT/GC electrode displayed remarkable tolerance to co-existing interferents, such as cysteine, ascorbic acid, uric acid and nitrite at the H _2O _2 detection potential in pH 7 PBS. The ability of the sensor electrode for routine analyses was demonstrated by the detection of H _2O _2 present in simulated milk samples with appreciable recovery values.