Gravimetric and dynamic deconvolution of global EQCM response of carbon nanotube based electrodes by Ac-electrogravimetry

• Capacitive charge storage of SWCNT was studied by ac-electrogravimetry.
• Ac-electrogravimetry deconvolutes the global EQCM response of SWCNT electrodes.
• It is both gravimetric and dynamic deconvolution, ions are identified by their Mw.
• In aqueous NaCl electrolyte, Na+·H2O, H+ and Cl− are electroadsorbed on SWCNT.
• Na+·H2O and H+ were electroadsorbed with different kinetics on SWCNT electrodes.

The capacitive charge storage of carbon nanotube (CNT) based electrodes was investigated by ac-electrogravimetry which couples fast quartz crystal microbalance (QCM) and electrochemical impedance spectroscopy (EIS). In contact with an aqueous NaCl electrolyte, evidence was found that there are two types of cations (Na+·H2O and H+) electroadsorbed with different kinetics for cathodic potentials and the Cl− ions for anodic potentials together with free water molecules. The reconstruction of the total mass response from independent ac-electrogravimetry measurements agrees perfectly well with the global EQCM response. Our findings reveal the unique sensitivity of the ac-electrogravimetry to provide a fair gravimetric and dynamic deconvolution of the global EQCM responses.

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