title: Platinum covering of gold nanoparticles for utilization enhancement of Pt in electrocatalysts.
abstract: This work attempts to enhance platinum utilization in a Pt-based electrocatalyst by the tuned covering of gold nanoparticles with small Pt entities. Reductive deposition of Pt on Au nanoparticles of two size ranges (Au-I: 10 +/- 1.2 nm, Au-II: 3 +/- 0.6 nm) up to different atomic Pt : Au ratios (m) was used to prepare two series of samples named Pt(m)insertion markAu-I and Pt(m)insertion markAu-II particles, respectively. The obtained Pt(m)insertion markAu particles were characterized with TEM, XPS, UV-Vis and XRD techniques, and then loaded on conventional Vulcan XC-72 carbon to make Pt(m)insertion markAu/C electrocatalysts. Cyclic voltammetry (CV) measurements showed that the electrochemical active surface area (EAS) and Pt utilization (U(Pt)) in Pt(m)insertion markAu/C were enhanced remarkably at m< or = 0.2 for Pt(m)insertion markAu-I/C or m< or = 0.5 for Pt(m)insertion markAu-II/C, in comparison to conventional Pt/C electrocatalyst. In particular, U(Pt) was enhanced to nearly 100% in Pt(m)insertion markAu-I/C catalysts at m< or = 0.05 and in Pt(m)insertion markAu-II/C at m< or = 0.1. In the CV measurement of methanol electro-oxidation, the specific mass activity of Pt in Pt(m)insertion markAu/C catalysts was found in proportional to U(Pt), confirming that the enhancement of Pt utilization is essential for the development of highly active Pt-based electrocatalysts. The highly dispersed Pt entities on Au nanoparticles proved to be stable during the electro-oxidation of methanol. Our study also showed that the use of smaller Au nanoparticles is advantageous for the generation of more active Pt catalyst at higher atomic Pt : Au ratios.
authors.affiliation: Innovative Catalysis Program, Key Lab of Organic Optoelectronics & Molecular Engineering, Department of Chemistry, Tsinghua University, Beijing, 100084, China.
authors.forename: Dan
authors.initials: D
authors.lastname: Zhao
authors.forename: Bo-Qing
authors.initials: BQ
authors.lastname: Xu
mesh_terms: D002384:Catalysis; D003460:Crystallization; D004563:Electrochemistry / Q000379:methods; D006046:Gold / Q000737:chemistry*; D046529:Microscopy, Electron, Transmission; D053758:Nanoparticles / Q000737:chemistry*; D036103:Nanotechnology / Q000379:methods; D010100:Oxygen / Q000737:chemistry; D010984:Platinum / Q000737:chemistry*; D013499:Surface Properties; D014961:X-Ray Diffraction
chemical_list: D010984:Platinum; D006046:Gold; D010100:Oxygen