Fabrication of Rhodium-modified Nickel Foam Cathodes for Nitrate Reduction"

The cathodic reduction of nitrate is a process actively investigated for the fundamental interest in its reaction mechanism and the practical challenge of environmental remediation. Among the electrode materials, the Cu-Ni alloy has received limited attention despite the good catalytic performances of copper, nickel and several of their alloys with other metals [1]. We have performed deposition of Cu-Ni alloys of different composition from a citrate bath [2] and tested their performances in the electroreduction of nitrate and nitrite in alkaline solution. Voltammetric experiments performed at RDE (900 rpm) in a solution of 10 mM NaNO3 and 1.0 M NaOH (Figure) show that on Cu-Ni alloys (especially for Cu = 70-95 at%) the nitrate reduction starts at less negative potentials than on Cu. Chrono-amperometries show that upon polarisation the current decays in time comparatively less on copper-rich alloys than on copper. The alloy has been deposited on different substrates including a commercial Ni foam (Incofoam®), a chemically stable, large surface substrate (specific surface area > 200 cm2 for 1 cm3 volume of Ni foam) with a porosity in the range of hundreds of ?m. Results of electrolyses at Cu-Ni modified Incofoam® electrodes are discussed and compared with those obtained at copper electrodes, as a function of the applied potential and the other operating parameters.