Post on 17-Feb-2018
Probing the nanoelectrical characteristics of a substance as an electrochemical reaction takes place is of interest in a variety of research fields, from biochemistry and corrosion to battery development. Bruker offers a variety of advanced options for electrochemical scanning probe microscopy (SPM), including our patented Scanning Electrochemical Potential Microscopy (SECPM) mode, which investigates electrochemical changes across a sample’s surface.
Bruker’s SECPM enables in-situ imaging or potential mapping of the electrode surface with nanometer-scale resolution. The electrochemical potential, φ, changes with distance across the electrical double layer at solid/liquid interfaces. SECPM measures the potential difference between its potentiometric probe and the sample, immersed in an electrolyte solution or a polar liquid. Moreover, scanning tunneling microscopy (STM) is integrated with the mode, offering combined power, flexibility, and comparison of images and data captured with the two techniques.
Scanning Electrochemical Potential Microscopy
Resolution of STM in a Dynamic Chemical Environment
Bruker’s SECPM solution includes a bipotentiostat/galvanostat, liquid cell, and attachments, and is available for the MultiMode 8-HR™ AFM (left). The integrated SECPM-STM head works in either STM mode or SECPM mode through software control (right).
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Bruker Nano Surfaces Division
Santa Barbara, CA • USA Phone +1.805.867.1400 productinfo@bruker.com
www.bruker.com/afm
Three Modes of SECPM Operation
Constant Potential Mode:In this mode, SECPM uses SPM feedback to adjust the position (height) of the probe relative to the sample surface to maintain a constant value of φ. When the probe raster-scans the sample surface (in X and Y), SECPM captures topograhic images of the sample surface.
Constant Height Mode:In this mode, SECPM’s feedback is turned off, and when the probe is raster-scanned, SECPM maps the electrochemical potential distribution across the sample surface.
Spectroscopic Mode (or Potential Profiling):SECPM’s raster-scanning (in X and Y) is disabled in this mode. Instead, the probe is scanned (in Z) across the electrical double layer, and the SECPM records a plot of the measured potential versus distance traveled.
With nanoscale in-plane resolution in these three modes, SECPM can provide new insights into electrochemical fundamentals for electroplating, corrosion, and battery research and development, as well as many other application areas.
SECPM constant potential mode image of Sn60Pb40 alloy in glycerol at open circuit potential using uncoated Pt-Ir tip at
potential (φ) setpoint of 100 mV. The open circuit potential is -520 mV vs. Pt quasi reference electrode. Scan rate: 0.5 Hz, 5 µm scan.
SECPM constant potential mode image of Au/quartz in 0.115 M KCIO4, captured at electrochemical potential (F) setpoint of 100 mV, 250 nm scan.
An example of SECPM electrochemical potential spectroscopy. These plots of potential (φ) vs. probe-sample distance were recorded above a HOPG sample in glycerol as the probe approached (white plot) and retracted (yellow plot) from the sample.
Reference Electrode
Working Electrode= Sample
Counter Electrode
Potentiostat
Potentiometer
Potential Gain
Sensitivity (mV/V)
Electrochemical Potential Measurement
Resolution (mV)
Maximum Measured Electrochemical
Potential (V)
1 1000 0.5 10
10 100 <0.1 1.0
50 20 <0.1 0.2
100 10 <0.1 0.1
SECPM specifications. >1013 Ω input impedance; <5 mV offset.
SECPM function diagram showing the interaction at the probe and sample site.