Activity of Small Silver Nanocubes as Activators for Electroless Copper Deposition

Small (12 nm) Ag nanocubes enclosed by (100) facets were successfully synthesized using Pt seed-mediated growth method for catalyzing electroless copper deposition (ECD). The activities and resulting ECD kinetics were of Ag nanocubes enclosed by (100) planes and Ag nanoparticles (17 nm) governed by (111) planes were compared. The deposition kinetics was investigated using an electrochemical quartz crystal microbalance (EQCM). The results showed that the induction period of the nanocubes (observed by a potential-deposition time curve) was 34 s, consistent with the incubation time obtained by the curve of frequency change vs. deposition time. The potential at which steady-state deposition occurs was independent of the Ag catalyst facets. At a deposition time of 500 s, the mean mass activities (in terms of the weight of the catalyst for the nanocubes and nanoparticles) were determined to be 1.959 and 0.9527, respectively. The smaller Ag nanocubes showed a twofold higher mass activity than the Ag nanoparticles. In a careful comparison based on the same electrochemical surface area (ESA), the specific activity in terms of ESA demonstrated that the Ag nanocubes showed a better ECD activity (5.99 × 10−2 mg cm−2) than the Ag nanoparticles (4.37 × 10−2 mg cm−2); thus, the nanocubes enabled faster ECD. Additionally, the data (supported by Tafel plots and CV curves normalised to the ESA) inferred that the greater specific activity of the nanocubes could be attributed to a higher oxidation power for anodic formaldehyde. The process deposited a Cu film with less CuO via the (100) planes of the nanocubes.