Characterization of hydrogen gas diffusion electrodes for reduction of metal from industrial process liquids

Kurzfassung

Gas diffusion electrode can be operated in a lot of electrochemical processes and devices like fuel cells, electrolysis and cleaning of waste water from electrochemical treatments of metals as electrochemical machining, electrochemical drilling and galvanic processes. Carbon black supported platinum is mixed with PTFE in a knife mill and rolled onto a metal web to form an electrode to manufacture the electrodes. The electrodes were characterized before and after electrochemical operation with X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM). Induced by the rolling process of the PTFE - carbon black - powder to the electrodes the PTFE forms thin fibres which are spined a web in the electrode. The surface composition of the electrodes for electrochemical metal treatment and cleaning of galvanic waste water change during operation time. Caused by the presence of metal ions in the liquid electrolyte in these applications metal is deposited onto the electrode surface during the operation time. Depth profiling of used electrodes shows that metal is not only deposited on the surface, but also can be observed in the electrodes.