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Scanning Probes & Fuel Cell Research

Latest updated: April 22, 2020

Fuel cells are one technology of interest in a growing hydrogen economy. Scanning probe electrochemistry has been used to help answer a number of questions about fuel cells as outlined below.

 

Question Technique Information Measured Example
Can the bacterial growth and attachment of different Microbial Fuel Cells (MFC) be quantitatively compared? SKP SKP sensitively measures the work function difference between the probe and sample. When the bacteria attaches to an MFC anode, the surface potential of the anode changes, which is detected by SKP. Increased attachment of the bacteria is reflected by a more negative shift of the work function difference. B. R. Sreelekshmy et al., Journal of Materials Chemistry A 8 (2020) 6041
How do the electronic properties of hydrogen storage materials change with hydrogen electrosorption? SKP The electrosorption of hydrogen in hydrogen storage alloys leads to changes in their work function, due to increased surface roughness, and changes of the double layer capacitance from the presence of hydrogen in the crystal lattice. SKP detects this change in sample work function as a change in the contact potential difference with the known SKP probe. B. Losiewicz et al., Materials 13 (2019) 162
Is it possible to screen catalyst compositions for H2 fuel production? SDC In SDC all standard electrochemical experiments are performed in an electrochemical cell locally confined to a droplet at the sample surface. The activity of different catalysts can be screened by moving the droplet to regions of different catalyst compositions to locally test the effects of changing composition. Compositions with higher activities will be apparent from an increase in the measured current. B. H. Meeks et al., International Journal of Hydrogen Energy 45 (2020) 1940-1947
Is proton transport through membranes for polymer electrolyte fuel cells homogeneous? dc-SECM dc-SECM is chemically selective by biasing the probe to interact with the species of interest. Biasing the probe to interact with protons allows it to detect proton diffusion through the membrane. Regions with high rates of proton diffusion will cause a higher probe current than those with low rates of proton diffusion. dc-SECM approach curves can be used to determine the diffusion rate. T. Kallio et al., Electrochemistry Communications 5 (2003) 561-565
How does the fuel cell catalyst support affect the activity? dc-SECM dc-SECM can be used to screen the effect of different catalyst supports  using competition mode. In this mode, the probe is biased to interact with the same species as the catalytic sample. Lower probe currents indicate higher catalytic activity. If only the catalyst support is altered changes in probe current reflect changes in catalytic activity due to the support. J. Kundu et al., CARBON 50 (2012) 4534-4542
Can combinatorial libraries of fuel cell anode catalysts be quantitatively screened? dc-SECM dc-SECM can be used in generator collector mode to initially qualitatively screen a combinatorial library to determine the most active catalyst compositions.  SECM approach curves and CVs can then be performed on the most active compositions allowing the quantitative determination of the reaction rates. M. Black, J. Cooper, P. McGinn, Measurement Science and Technology 16 (2005) 174

 

Glossary:

  • Scanning ElectroChemical Microscopy (SECM): Measurement of local electrochemical activity of a sample with chemical selectivity. The local impedance of a sample can also be measured.
  • Localized Electrochemical Impedance Spectroscopy (LEIS): Measurement of local impedance differences and point-by-point Electrochemical Impedance Spectroscopy
  • Scanning Kelvin Probe (SKP): Local non-contact measurement of sample work function. Topography can also be measured.
  • Scanning Vibrating Electrode Technique (SVET): Measurement of local current distribution of a sample in electrolyte. Also known as Vibrating Probe.
  • Scanning Droplet Cell (SDC): Local electrochemical and impedance measurements of a sample within a droplet.
  • Optical Surface Profiler (OSP): Non-contact measurement of local sample topography.

 

Scanning probe electrochemistry SECM LEIS SKP SVET SDC OSP Vibrating Probe.