Photo-electrochemical properties of quantum rods studied by scanning electrochemical microscopy.

Scanning electrochemical microscopy (SECM) is used for studying the intrinsic photo-electrochemical properties of CdSe/CdS quantum rods. They are deposited on a transparent and non-conductive glass plate and investigated by SECM in feedback and generator-collector modes using a series of redox mediators. The method allows the interrogation of the quantum rods under illumination without the interference of the substrate, notably that due to the electron photo-ejection from the substrate, a process that is inherent to any polarized electrode material.

Tunneling dendrimers. Enhancing charge transport through insulating layer using redox molecular objects.

Charge transport through an insulating layer was probed using ferrocenyl-terminated dendrimers and scanning electrochemical microscopy. Experiments show that the passage through the layer is considerably enhanced when the transferred charges are brought globally to the surface by the ferrocenyl dendrimer instead of a single ferrocene molecule. This result shows that charge tunneling through an insulator could be promoted by a purely molecular nano-object.

Locally induced and self-induced "electroclick" onto a self-assembled monolayer: writing and reading with SECM under unbiased conditions.

Localized "electroclick" was achieved on azido-terminated self-assembled monolayers using Scanning Electrochemical Microscopy (SECM) in feedback mode, in which the substrate is not electrically connected (unbiased conditions). The method allows both the local immobilization of diverse functional moieties and the monitoring of each modification step at a micrometer scale. Conditions of the "click" coupling reaction were optimized especially to avoid the deposit of metallic copper by the choice of a specific ligand to stabilize the Cu(I) species.

Chemically irreversible redox mediator for SECM kinetics investigations: determination of the absolute tip-sample distance.

The use of a chemically irreversible redox probe in scanning electrochemical microscopy (SECM) was evaluated for the determination of the absolute tip-substrate distance. This data is required for a quantitative use of the method in the analysis of functional surfaces with an unknown redox response. Associated with the relevant model curves, the electrochemical response allows an easy positioning of the tip versus the substrate that is independent of the nature of the materials under investigation.

Use of catechol as selective redox mediator in scanning electrochemical microscopy investigations.

The use of catechols, and more specifically of dopamine, as a specific redox mediator for scanning electrochemical microscopy (SECM) investigations was evaluated in the challenging situation of an ultrathin layer deposited on a conductive substrate (carbon materials). Experiments show that dopamine is a well-adapted redox system for SECM in feedback mode and in unbiased conditions. Used as a redox mediator, catechol permits the investigations of modified surfaces without an electrical connection of the sample thanks to fast charge transfer kinetics but with a surface selectivity that does not exist in classical outer-sphere redox mediators.

Accurate and simplified consideration of the probe geometrical defaults in scanning electrochemical microscopy: theoretical and experimental investigations.

Fabrication of scanning electrochemical microscopy (SECM) tips cannot always guarantee a perfect disk geometry. In the present work, the impact of these defaults is investigated both theoretically and experimentally. The situations where these defaults can accurately be taken into account by considering that the probe behaves like a microdisk with effective geometric parameters are determined.