Electrocatalytic formation of polymolecular products at the cathodic polarization of polycrystalline chromium in sulfuric acid solutions of formic and oxalic acids

The cathodic behavior of polycrystalline Cr electrodes in sulfuric acid solutions of oxalic (OA) and formic (FA) acids is studied by cyclic voltammetry. These organic substances not only chemisorb on the electrode surface thus severely hindering the hydrogen evolution on the metal but also take active part in the electrocatalytic reactions that occur under these conditions. The use of methods of chromatography mass spectrometry and photon-correlation spectroscopy demonstrates that long-term cathodic polarization of Cr in the potential range of active hydrogen evolution (in the vicinity of ?1.0 V) in sulfuric acid solutions containing FA and OA leads to the formation of polymolecular compounds. Among the latter, linear hydrocarbons and carboxylic acids containing 12–27 carbon atoms are isolated and identified.