A team based at Kanazawa University has developed a microscopy approach called 3D open-loop electric potential microscopy (OL-EPM) to visualize the real-space charge distribution at the interface between an electrode and electrolyte. The researchers developed 3D OL-EPM by first optimizing their existing two-dimensional OL-EPM technique.

“传统OL-EPM受到影响的e long-range interaction between the sample and microscope tip and cantilever," says the first author Kaito Hirata. "We minimized this influence by improving the equations used to calculate the potential in OL-EPM."

这些改进方程能减去long-range force acting on the microscope tip and cantilever from the measured data. As a result, the short-range forces originating from charges accumulated in the electric double layer were observed as changes of the local surface potential. The ability of the improved equations to calculate interfacial charge distributions was determined using two electrodes with different charge accumulation behavior. The opposite charge accumulation characteristics at the two electrodes were successfully captured using the improved OL-EPM equations.

The improved OL-EPM approach was then combined with a 3D tip scanning technique to provide 3D OL-EPM. The team used 3D OL-EPM to visualize the charge accumulation at the interface between a copper wire electrode and salt electrolyte. The obtained results provided valuable information about the charge distribution at the electrode-electrolyte interface.

"We can use 3D OL-EPM to investigate electrochemical reactions and local solution conditions at electrode-electrolyte interfaces," explains the corresponding author Takeshi Fukuma. "The information obtained from such experiments is important for fields such as electrochemistry, electronics, and biology."

The ability to obtain real-space data about the nanoscale charge distribution at electroactive interfaces promises to increase our understanding of interfacial phenomena and aid progress in electronics and battery research.