Exploring the Use of Different Carbon Materials Within Additive Manufactured Electrodes: The Sensing of Carbendazim

Additive manufacturing is emerging as a technology utilised within the field of electrochemistry, where researchers need to understand the electrochemical capabilities of the electrodes produced. One aspect yet to be fully explored is the effect of using different carbon morphologies and how these differences affect the electrochemical performance. It is understood that edge plane defects are the site of electrochemical activity, therefore, quantifying these defect sites will allow for determination of which morphology is most advantageous. Various filaments containing different morphologies were produced in combination with carbon black (CB) using multiwalled carbon nanotubes (MWCNTs), carbon nanotube clusters, and graphite. All electrodes were subject to physicochemical characterisation using scanning electron microscopy, Raman, and X-ray photoelectron spectroscopy. MWCNTs in combination with CB produced a high performing electrically conductive filament, which showed improved electrochemical performance compared to other bespoke filaments with a heterogenous electron transfer of k⁰_obs of 3.22 (±0.16) x 10⁻³ cm s⁻¹. The filament containing MWCNTs was also found to show the largest density of edge plane sites of 0.81% and was closest to that of a glassy carbon electrode. All electrodes were successfully tested for the detection of carbendazim producing linear ranges between 5 and 40 μM. The MWCNT filament also exhibited the best electroanalytical performance, showing a limit of detection of 0.26 μM and limit of quantification of 0.88 μM, as well as achieving a recovery of 114% in a river water sample. This work proves that the edge plane defect sites are the site of electrochemical activity within additive manufactured electrodes and should be considered when designing new materials.