Effect of boron concentration on the electrochemical reduction of nitrates on polycrystalline diamond electrodes

Abstract

Abstract The Raman spectra and voltammograms in 0.1 M KCl, 0.1 M KNO 3 and 0.1 M KCl+0.1 M KNO 3 solutions of polycrystalline diamond electrodes vary systematically versus their boron content in the gas phase (200 to 14 000 ppm). Both exhibit the same threshold (2000 ppm, about 1.2×10 20 B cm −3 ) corresponding to the appearance of a low-wavenumber continuum in Raman spectra and to a factor of 10 3 jump in the electrochemical current. In 0.1 M KNO 3 solution, the reduction of nitrates from −0.6 to about −2 V cathodic potential occurs with low hydrogen reduction. The correlation between the electronic and electrochemical properties of these electrodes is discussed.