Electrocatalytic Activity of Semiconductor Electrodes Modified by Surface-Deposited Metal Nanophase

Electrocatalytic Activity of Semiconductor Electrodes Modified by Surface-Deposited Metal Nanophase 

It is well known that non-degenerated wide-band semiconductors tend to have low electrocatalytic activity. In particular, in the dark conditions under the electrode potentials higher than the flat-band potential (Efb), Ti02 electrodes with ordinary doping (Na = 1017 - 

On examination of the electrocatalytic activity of metal nanoparticles in dark electrode processes, of significant interest is the appearance of the limiting current on the i,V curve for the Cu-modified Ti02 electrode, especially taking into account that it does not depend on the stirring of electrolyte and cannot be considered as a consequence of any diffusion limitation caused by the electrolyte solution. At the same time, this limiting current is very sensitive to the heating of the electrolyte as well as to the IR illumination of the electrode. 

To understand the above peculiarities of the electrocatalytic activity of metal nanophase in dark oxidation processes on the Ti02 electrodes, one should take into account the differences in the inherent electrocatalytic properties of deposited metals, on the one hand, and the data on the electronic states formed by the nanoparticles of these metals in a band gap of Ti02 electrode, on the other hand. A peculiar shape of i,V-curves obtained for 

From the above reasoning one could expect that the pre-deposition of small amounts of noble metals on the Ti02 surface in a form of the intermediate sub-layer, which can induce the electroactive electronic surface states in the Ti02 band gap, may enhance the electrocatalytic effect of subsequently deposited Cu particles. Actually, the photocatalytic deposition of silver particles in amount of 5xl014 atoms/cm-2, which on its own only slightly increases the electrocatalytic activity of Ti02 electrode, leads to 2-3-fold enhancement of the electrocatalytic activity of Cu particles subsequently deposited in a relatively high concentration (1016-1017 atoms/cm 2) [52], 

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