Corrosion of ternary Mn-Cu-Au to nanoporous Au-Cu with widely tuned Au/Cu ratio for electrocatalyst

By one-step dealloying a single phase Au5Cu25Mn70 alloy, nanoporous AuCu alloys (np-AuCu) with widely tuned Au:Cu ratio are obtained. The one-step corrosion in (NH4)2SO4 solution involves two step dealloying process. The first one is fast dealloying of Mn, resulting in np-Au16Cu84. The second step is slow etching of Cu, which is used to tune the ratio of Cu/Au on the AuCu nano-ligament surface. Electrochemical measurements exhibit that the electrocatalytic activities of ultrafine np-AuCu towards glucose oxidation and H2O2 reduction depend on the ratios of the Au:Cu. The activities follow the order that np-Au66Cu34 > np-Au58Cu42 > np-Au78Cu22 > np-Au.