Coverage-dependent electro-catalytic activity of Pt sub-monolayer/Au bi-metallic catalyst toward methanol oxidation

•The Pt nanofilm/Au catalytic properties were studied for the methanol oxidation.•The Pt nanofilm formed on Au was fabricated through a precise manner.•The Pt nanofilm coverage-dependent behavior was observed.•The catalytic activity initiated at the Pt surface coverage around 0.2.•The catalytic activity reached its maximum around 0.6.

The coverage-dependent catalytic properties of a Pt nanofilm formed on a Au substrate were investigated for the electro-oxidation of methanol. The coverage of Pt nanofilm was precisely fabricated by the formation of coverage-controlled under potential deposition of Cu adlayer and followed by the surface limited redox replacement reaction with different Pt complex ions. The STM images exhibit the formation of Pt nano-film on Au substrate with different coverage. It was clearly shown that the activity of Pt nanofilm deposited on Au substrate toward the methanol electro-oxidation was highly sensitive to its surface coverage. Pt–Au bimetallic catalyst was found to become active at the Pt surface coverage near 0.2 and reached its maximum around 0.6. The electro-catalytic activity as well as CO tolerance on Pt–Au bimetallic system was found higher than those on a Pt electrode.