Nanoscale intermittent contact-scanning electrochemical microscopy
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A major theme in scanning electrochemical microscopy (SECM) is a methodology for nanoscale imaging with distance control and positional feedback of the tip. We report the expansion of intermittent contact (IC)-SECM to the nanoscale, using disk-type Pt nanoelectrodes prepared using the laser-puller sealing method. The Pt was exposed using a focused ion beam milling procedure to cut the end of the electrode to a well-defined glass sheath radius, which could also be used to reshape the tips to reduce the size of the glass sheath. This produced nanoelectrodes that were slightly recessed, which was optimal for IC-SECM on the nanoscale, as it served to protect the active part of the tip. A combination of finite element method simulations, steady-state voltammetry and scanning electron microscopy for the measurement of critical dimensions, was used to estimate Pt recession depth. With this knowledge, the tip-substrate alignment could be further estimated by tip approach curve measurements. IC-SECM has been implemented by using a piezo-bender actuator for the detection of damping of the oscillation amplitude of the tip, when IC occurs, which was used as a tip-position feedback mechanism. The piezo-bender actuator improves significantly on the performance of our previous setup for IC-SECM, as the force acting on the sample due to the tip is greatly reduced, allowing studies with more delicate tips. The capability of IC-SECM is illustrated with studies of a model electrode (metal/glass) substrate.
KeywordsSECM Nanoelectrode Nanoscale electrochemical imaging Focused ion beam (FIB) milling
This work was supported by the Engineering and Physical Sciences Research Council (EPSRC) project studentship for R.L. (Grant EP/H023909/1) and MOAC/DTC studentships for K.M. and M.B. We acknowledge support from a European Research Council Advanced Investigator Grant (ERC-2009-AdG247143 QUANTIF) for P.R.U and K.M. Some of the equipment used in this research was obtained through Birmingham Science City with support from Advantage West Midlands and the European Regional Development Fund. We thank Robert B. Channon and Andrew J. Soulby for their early contributions to the work. We are grateful to Dr. Alex W. Colburn for designing and building the electronic instrumentation used herein.
- 49.Nioradze N, Chen R, Kim J, Shen M, Santhosh P, Amemiya S (2013) Anal ChemGoogle Scholar