Hot-Tip Scanning Electrochemical Microscopy: Theory and Experiments Under Positive and Negative Feedback Conditions

Area of Science:

• Electrochemistry
• Surface Science
• Analytical Chemistry

Background:

• Scanning electrochemical microscopy (SECM) is a powerful surface analysis tool.
• Conventional SECM can be limited by mass transfer rates.
• Novel techniques are needed to enhance SECM capabilities.

Purpose of the Study:

• To investigate the performance of hot-tip scanning electrochemical microscopy (HT-SECM).
• To understand the effects of electrothermal fluid flow (ETF) on HT-SECM measurements.
• To explore the potential of HT-SECM for studying electrode kinetics.

Main Methods:

• Utilizing an alternating current (ac) polarized disk microelectrode for resistive heating.
• Applying high-frequency (∼100 MHz) ac waveform to induce electrothermal fluid flow (ETF).
• Recording approach curves and cyclic voltammograms in positive and negative feedback modes.
• Performing numerical simulations using COMSOL Multiphysics.
• Developing analytical approximations for faradaic response prediction.
• Theoretically studying the Soret effect contribution.

Main Results:

• HT-SECM demonstrated increased mass transfer rates due to resistive heating and ETF.
• The hot tip resulted in more pronounced feedback compared to room temperature measurements.
• Experimental findings were supported by numerical simulations.
• Analytical approximations were developed for predicting faradaic currents.
• The Soret effect was theoretically analyzed.

Conclusions:

• HT-SECM is an effective technique for enhancing mass transfer in SECM.
• The elevated temperature and convection improve the sensitivity and resolution of surface analysis.
• HT-SECM offers a promising approach for investigating electrode kinetics under dynamic conditions.
• This study provides a comprehensive understanding of HT-SECM, paving the way for its broader application.