Research project: Denuault: Nanostructured microelectrodes

These microelectrodes present the unique feature of having a large electroactive area (up to 1000 times greater than that of the bare electrode) while retaining the diffusional properties of conventional microdiscs. Such unique combination of properties is useful for redox processes involving an adsorption or absorption step. The modified electrode offers a huge number of active sites and its catalytic properties are significantly improved. E.g. the voltammetry of oxygen is markedly different on mesoporous microdiscs. Similarly, we found that the voltammetry of hydrogen peroxide is dramatically improved.

For more details see the following publications:

• Evans, Mesoporous Platinum Microdisc Electrodes and the Detection of Hydrogen Peroxide in Analytical Chemistry and Scanning Electrochemical Microscopy, PhD thesis, University of Southampton, Southampton, 2002.
• Evans et al., Detection of Hydrogen Peroxide at Mesoporous Platinum Microelectrodes, Anal. Chem. 74, 2002, 322-1326.

We have also studied the potentiometric properties of microdisc electrodes modified with nanostructured films. In the example below nanostructured Pd films deposited onto Pt microdisc electrodes are loaded with hydrogen to form a palladium hydride and used to measure pH potentiometrically. Thanks to the nanostructure these electrodes yield a very good potentiometric response with a level of quality (reproducibility, agreement with theory, stability, etc…) not found with conventional microelectrodes. We are using these electrodes as SECM tips for the localised detection of pH.

 

 

 

 

For more details see the following publications:

• Imokawa, Fabrication and characterisation of nanostructured palladium hydride microelectrode pH sensors, PhD Thesis, University of Southampton, Southampton, 2003.
• Imokawa et al., Fabrication and characterization of nanostructured Pd hydride pH microelectrodes. Anal Chem, 2006. 78(1): p. 265-71.

Recently we have applied this methodology to study pH changes during carbonation of lime:

Serrapede, et al., Nanostructured Pd Hydride Microelectrodes: In Situ Monitoring of pH Variations in a Porous Medium. Analytical Chemistry, 2014. 86(12): p. 5758-5765.