Attempts are made in this study to manipulate nanostructures of Pt-flecks on Ag nanoparticles (Pt m ∧ Ag) for advanced electrocatalysts by reflux citrate reduction of Pt from Pt II Cl 4 2− or Pt IV Cl 6 2− ions in solution containing Ag colloids at different atomic Pt/Ag ratio ( m ). Characterizations with UV−vis, SERS, XPS, and XRD showed a gradual Pt covering of the Ag colloids with increasing m when Pt II Cl 4 2− was the precursor of Pt (Pt m ∧ Ag−A samples). However, due to an involvement of the galvanic replacement reaction between Pt IV Cl 6 2− and the metallic Ag colloids during the citrate reduction of Pt IV Cl 6 2− ions, a distinct alloying of Pt with the underlying Ag particles took place at the surface region of the colloidal Ag particles when Pt IV Cl 6 2− was the precursor of Pt (Pt m ∧ Ag−B samples). Cyclic voltammetry (CV) measurement of the electrochemically active surface area (EAS) showed that the Pt utilization ( U Pt ) in Pt m ∧ Ag−A increased with the decrease in m . The mass-specific activity (MSA) of Pt for the electrooxidation of either methanol or formic acid increased linearly with U Pt in Pt m ∧ Ag−A, but was enhanced significantly with proper Pt−Ag alloying in Pt m ∧ Ag−B catalysts. Fine-tuning the extent of Pt−Ag alloying resulted in optimized Pt m ∧ Ag−B catalyst at 0.47 ≤ m ≤ 0.53, whose activity by MSA of Pt was 1 order of magnitude higher in methanol electrooxidation and six times higher in formic acid electrooxidation than its Pt m ∧ Ag−A counterpart of similar U Pt .
No takes yet. Share an insight, caveat, or question.
Zhao et al. (2009) studied this question.
Synapse has enriched 5 closely related papers on similar clinical questions. Consider them for comparative context: