Catalysis of Hydrogen Evolution on Au(111) Modified by Spontaneously Deposited Pd Nanoislands

Hydrogen evolution reaction was studied on Au(111) modified by palladium spontaneously deposited on the Au(111) surface from (1 mM PdSO4 center dot 2 H2O + 0.5 M H2SO4) solution at a submonolayer coverage. Number and size of Pd islands increased with the increase of the deposition time as observed by ex situ surface topography atomic force microscopy (AFM). The overall coverage of the underlying Au(111) surface by the deposited Pd islands was estimated from simultaneously acquired phase AFM images, which provided a clear contrast between different materials. The obtained Pd/Au(111) surfaces have shown a significant catalytic activity toward hydrogen evolution reaction in 0.5 M H2SO4 solution. This is discussed with respect to Pd islands size and coverage and to the influence of an electronic effect induced in Pd islands by the underlying Au(111) substrate.