Abstract:

"pH- open circuit potential" relationship was investigated for Ir/IrO2 micro plane pH sensing electrode in the solution systems composed of different primary alcohols and their electrochemically oxidized products carboxylic acids. pH variation with the distance apart from electrode surface within 50 μm was measured in situ during electrochemical oxidation of three primary alcohols. Comparison and analysis were made for the H+ concentration generated by electrochemical oxidation of the primary alcohols. The experiment revealed that the relationship of "pH- open circuit potential" of the Ir/IrO2 micro plane electrode was related to the kind of the "alcohol-carboxylic acid" system. The H+ concentration generated by electrochemical oxidation of glycol was highest, methanol comes second, and ethanol’s was lowest. Through the addition of NaF in the electrolyte, the selective micro-area etching function for titanium was examined by means of HF generated through metathytical reaction between organic acid and the NaF.

Key words: primary alcohols, electrooxidation, pH measurement, Ir/IrO2 micro plane electrode, etching