Hydrogen evolution assisted electrodeposition of porous Cu-Ni alloy electrodes and their use for nitrate reduction in alkali

Porous Cu-Ni alloys with a wide range of compositions have been deposited from citrate baths containingthe two metal ions, under application of large current densities (-3 A cm−2) leading to vigorous hydrogenevolution. The deposited alloy layers show macroscopic porosity and a spongy material made of a networkof tiny dendrites. Porous RDEs reveal a significant current increase – as compared to ordinary polishedelectrodes – in the fast ferrocyanide reduction under pure mass transport control. Voltammograms ofnitrate reduction in alkali at porous RDEs show at all potentials larger currents in comparison withexperiments at compact electrodes of same composition. Electrolyses at porous sheet electrodes showlarge stable currents, leading to fast and selective nitrate reduction to ammonia.