Simultaneous topographical and amperometric imaging of surfaces in air: towards a combined scanning force-scanning electrochemical microscope (SF-SECM)

The first simultaneous images of electrochemical activity and surface topog raphy of a substrate in air are reported using a combined scanning force mi croscope (SFM) and scanning electrochemicaI microscope (SECM): SF-SECM. In the SF-SECM, the amperometric response of a Pt-coated SFM tip connected as a working electrode is monitored as the probe is scanned over the surface, in contact mode, enabling topographical and electrochemicaI maps of the sur face to be generated simultaneously. This methodology is illustrated throug h studies of the surface of a track-etched porous membrane (pore diameter 1 00 nm), hydrated with a solution containing 5 X 10(-3) mol dm(-3) potassium hexachloride iridate(III) (electroactive mediator) in excess supporting el ectrolyte. The optimal conditions for the preparation of the most effective and durable Pt thin film-coated probe, essential for the production of a l ong-lasting conducting tip, are also determined. (C) 1999 Elsevier Science S.A. All rights reserved.