| 초록 |
In general, the evaluation of the targeted electrode in photo(electrochemical) system is conducted in conventional three-electrode system comprising of working, counter and reference electrode in a batch cell configuration. Depending on the targeted electrode, the proper use of counter electrode, balancing the reaction of the working electrode, is recommended to avoid contamination unexpectedly arising from the electrochemical system. Herein, fundamentals of electrochemical analysis are introduced with two different model systems, highly sensitive to the chemical changes on electrode surface. First, we have investigated a model reaction of hydrogen evolution reaction (HER) in a conventional three-electrode system, employing p-Si photocathode, Pt counter, and Ag/AgCl reference electrodes. Alternatively, identical reaction has also been investigated on a polycrystalline platinum cathode, Pt(poly), with a graphite counter electrode. Significant overestimation/underestimation of the HER activity was verified. Potential variations on the Pt counter electrode were concurrently monitored during the evaluations, of which results were coupled to the online inductively coupled plasma-mass spectrometry (ICP-MS) and in situ differential electrochemical mass spectrometry (DEMS), to monitor metal dissolution and carbon corrosion simultaneously during the reactions. Significant dissolution of Pt counter and Ag/AgCl reference electrodes and their consecutive redeposition on p-Si photocathode were confirmed in the former system, while strong site-blockages of active Pt surface by CO evolved from graphite counter electrode were demonstrated in the latter one. From these model studies, we can suggest the suitable form of electrochemical system based on the targeted electrode for precise measurement. |
