Highly defective carbon nanotubes for sensitive, low-cost and environmentally friendly electrochemical H2O2 sensors: Insight into carbon supports

Abstract

We employed the oxidative dehydrogenation of C2H2 by CO2 and the C2H2 decomposition to prepare carbon nanotubes (CNTs) and carbon nanofibers (CNFs). The use of a small amount of Ni catalyst made it possible to produce CNTs and CNFs having a highly defective structure at a relatively low temperature compared to the one typically used for the CNT synthesis. The synthesized CNTs and CNFs were decorated with about 10 nm-gold nanoparticles (AuNPs) via an electrostatic self-attachment. The electrode with CNTs synthesized via the C2H2–CO2 reaction exhibits superior electrochemical reactivity with H2O2 when compared to the ones with CNTs synthesized via C2H2 decomposition, commercial CNTs, CNFs, and other more common carbon supports e.g. carbon black and activated charcoal. It demonstrates a rapid response, high sensitivity (104.9 μA mM−1 cm−2), wide linear working range (5 μM–23 mM), low detection limit (0.138 μM), good selectivity, reproducibility, and stability. The CNTs synthesized via the C2H2–CO2 reaction are suggested as energy-saving, cost-effective and environmentally friendly supporting material candidates for practical applications. The electrodes with CNTs show a high electrochemically active surface area, low charge transfer resistance and fast mass transfer at the electrode surface that are key factors for H2O2 detection.