Planar gold electrode

As one example, let us examine a system studied by Grossman (1973). The cell uses two planar gold electrodes in aqueous NaCl solution (0.12n). Initially Na, Cl , and OH" are present in solution. A steady current is passed through the cell from an external source. 

Figure 7. Anodic peak currents as a function of (A) scan rate v, and (B) square root of scan rate (v ), for Aims coated on 0.04 cm planar gold electrodes containing, (O) 40%, ( ) 44%, (v) 47%, ( ) 52%, ( ) 57% and ( ) 64% GOx by weight. Solution as in Figure 4.

Han S, Lindholm-Sethson B (1999) Electrochemistry at ultrathin polyelectrolyte films self-assembled at planar gold electrodes. Electrochim Acta 45 845-853... 

A miniaturized planar amperometric glucose sensor has been created on Sapphire substrates. Thin film titanium-gold electrodes are covered with an enzyme layer which is patterned by a lift-off technique [66]. This sensor exhibits a fast response time of 30 seconds but the linear measuring range is poor. 

The opportunity of obtaining direct electrochemistry of cytochrome c and other metalloproteins at various electrode materials such as modified gold and pyrolytic graphite has led to numerous reports of heterogeneous electron transfer rates and mechanisms between the protein and the electrode. In all the reports, Nicholson s method (37) was employed to calculate rate constants, which were typically within the range of 10" -10 cm sec with scan rates varying between 1 and 500 mV sec This method is based on a macroscopic model of the electrode surface that assumes that mass transport of redox-active species to and from the electrode occurs via linear diffusion to a planar disk electrode and that the entire surface is uniformly electroactive, i.e., the heterogeneous electron transfer reaction can take place at any area. 

One of the first AFM studies of DLforces was carried out by Hillier and Bard [41]. They measured the interaction force between a gold electrode and a modified AFM probe, as a function of electrode potential, electrolyte concentration, and chemical identity of the anion. A sifica sphere (10-20 p,m nominal diameter) attached to the end of the AFM cantilever functioned as the tip. This probe geometry is often adopted in AFM force measurements, in conjunction with a planar substrate, as the tip-sample geometry is well... 

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