A Dual-Barrel Carbon Fiber Microelectrode for Generator-Collector Experiments

Generator-collector systems have been intrinsically related to electrochemical studies for decades, from kinetics studies to quantification processes. Herein, a new protocol for fabricating a dual carbon fiber microelectrode using a dual-barrel capillary is described. The fabrication process involves the use of inexpensive carbon fiber and requires minimal specialized equipment, except for a micropipette puller. The resulting microelectrodes exhibit a microdisc geometry, which is advantageous due to their well-defined diffusion profiles. The electrode was characterized electrochemically and through imaging experiments (scanning electron microscopy). The device was then employed in a generator-collector mode, and using [Ru-(NH₃)₆]-Cl₃ as a redox probe in an SECM configuration, an increase in the collection efficiency was observed during the approach to an insulating substrate. The dual carbon fiber microelectrode was also explored to obtain analytical information based on the correlation between the collection efficiency in the iodide/iodine system and the thiosulfate concentration.