Electrodeposition of Cu-Rh alloys and their use as cathodes for nitrate reduction

Cu-Rh alloys have been electrodeposited from sulfate solutions, pH 3.4. Although Rh is more noble than Cu, the reduction peak of Rh 3+ was ca. 0.4V more negative than that of Cu 2+. Therefore, the Rh/Cu ratio in the deposited alloys, determined by EDS analyses, increased as the deposition potential became more negative. XRD analyses showed that the deposited alloys were polycrystalline and suggested that metastable Cu xRh 1-x solid solutions were formed for 0.1<=x<=0.8, although for such compositions a miscibility gap is known to exist. The Cu-Rh alloys were tested as cathodes for the reduction of nitrates and found to have significant catalytic activity.