(H2PtCl6 xH20, Various amounts of chloroplatnic acid Aldrich) and ruthenium chloride (RuCl3 xH2O, Aldrich) in 100 mL of water were prepared in a dropping funnel and added dropwise in a dropping rate of about 2 s per drop to the CuNWs suspension after flowing Ar for 15 min. The reaction continued for 1 h at room temperature to ensure a complete reaction.