The Δjpeak and Epeak values for Cu, Rh and some alloy electrodes are reported in the inset of Fig. 3. The dependence of Δjpeak on composition shows a maximum around 30 Rh at.% and suggests a synergistic effect of Cu and Rh in the reduction of nitrates. Alloy electrodes with ≥57 Rh at.% had H desorption charges of the same order as that of Rh; upon increasing the Rh content, their voltammetric curves changed from a single peak to patterns similar to that of Rh.