Semiconducting behavior of passive film formed on stainless steel in borate buffer solution containing sulfide
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The semiconducting behavior of passive film formed on 316L stainless steel in borate buffer solution containing sulfide was studied by capacitance measurements (Mott–Schottky approach), electrochemical impedance spectroscopy and potentio dynamic polarization curves. The results reveal that the measured capacitance values of the stainless steel electrode have frequency dependence and hysteresis, which shows amorphous or highly doped semiconductor property of the passive film. The Mott–Schottky plots indicate p-type semiconducting behavior related to chromium oxide and n-type semiconducting behavior to iron oxide at different potential range of stainless steel electrodes. The existence of sulfide in the solution increases the acceptor densities obviously which increase more than five times with the sulfide concentration of 9 mg L−1 and enables a more conductive behavior. The presence of sulfide also decreases the impedance values and enlarges the passive current of the electrode.
KeywordsStainless steel Passive film Sulfide Borate buffer solution Semiconducting behavior
The Project was supported by the Shanghai Committee of Science and Technology, China (Grant No. 08DZ2201400, 09DZ0500400, 10DZ0500300, and 10DZ2210400).
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