Collect. Czech. Chem. Commun. 1982, 47, 2724-2734

Studies on semiconductive nature of Brdička current

Matsuoki Shinagawa and Susumu Kakumoto

Research Laboratory, Matsushita Electronics Corporation, Saiwaicho-1, Takatsuki-shi, Osaka, Japan


Bovine serum or egg white shows a peak wave (so-called presodium wave) at c. -1.8 V (S.C.E.) in NH4Cl or LiCl solution. This wave is enhanced by adding iodine, o-chloranil or cobalt ions and depressed by hydroxyl ions. If ammonium hydroxide and Co(II) ions are added to the solution, a double wave appears for protein at c. -1.4 ~ -1.6 V or a single wave for cysteine at c. -1.6 V; the presodium wave is depressed. These phenomena correspond to the conductivity effect of organic semiconductor, showing that the c. -1.4 V is a n-type, the c. -1.6 V wave is an amphoteric type, and the presodium wave (c. -1.8 V wave) is a p-type wave. Such a n-, amphoteric or p-type current is caused by exchange of electrons and/or holes between mercury electrode (with or without Co) and its adsorbate at a proper cathodic potential. The latter types of the waves are partly modified by the effect of electron donors or acceptors, which change their height. They are simulated by an inorganic semiconductor, e.g., cobalt sulfide, by the suspension or press-on method as formerly reported. Consequently a hybridized electrode surface system composed of Hg (with or without Co)/solution and Hg (with or without Co)/semiconductore/solution is considered to be closely related to the Brdi_ka current. Some results of studies on the relation between polarographic behaviour and semiconductor characteristics are reported.