Characterisation of complex electrode processes using simultaneous impedance spectroscopy and electrochemical nanogravimetric measurements

The methodology and illustrative examples of application are presented for a technique that simultaneously combines electrochemical impedance spectroscopy (EIS) and nanogravimetric measurements; the latter are implemented using a so-called electrochemical quartz crystal nanobalance (EQCN). The combination of EIS and EQCN provides a powerful method for the characterisation of many complex processes at electrochemical interfaces. This method gives in one relatively simple experiment more detailed information than is available from conventional electrochemical techniques. The combined measurements can be performed either as a function of time, at a constant electrode potential, or under potentiodynamic conditions, as a function of the electrode potential. Herein, we show how this can be applied to enable more accurate investigation of processes that occur at boundaries between electrodes and electrolytes. The application examples range from eletrocatalysis, in which evaluation of a catalyst is performed simultaneously with its formation, and the intercalation and electrodeposition of thin metal films to in situ characterisation of non-electroactive self-assembled monolayers during their formation.