Voltage reduction sequence

The growth of the oxide layer is snch that it advances into the aluminum phase with simultaneous formation and dissolntion of the oxide to form the pores. During the pore formation, the aluminum anode material is never directly exposed to the solution since it is always coated by a relatively thin (10-100 nm) non-porons insulating oxide layer called the barrier layer (see Figure 16.2.2A). Various procedures can be used to separate the unoxidized aluminum from the porous oxide layer (14, 24). The most widely used is the so-ealled voltage reduction sequence (VRS) developed by Fumeaux et al. (22). VRS entails the stepwise reduction of the potential so that a progressive reduction of the pore diameter is produced at the bottom of the pore (see Figure 16.2.2). 

The potential difference for reduction and oxidation (Ae 2.6 V) provides sufficient energy to generate an excited Ir complex in the annihilation reaction. At an ac voltage of 4 V and 10 Hz we observed a weak eel of Ir(ppy) in acetonitrile. The following reaction sequence may explain this observation ... 

In DNA sensors based on PtNP labels, capture of the PtNP-labeled target sequence at the cathode end of a BPE resulted in the catalytic reduction of dissolved oxygen and led to the oxidation of the ECL reporter Ru(bpy)3 and coreactant tri- -propylamine at the anode end. Since BPEs do not require direct contact with a voltage source, many BPEs can be controlled by the electric field... 

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