Dissolution of Platinum Single Crystal Surfaces under Potential Cycling in Sulfuric Acid Solution

The dissolution of Pt(100), Pt(110), and Pt(111) single crystal surfaces under potential cycling conditions in 0.5 M H2SO4 solution was investigated by electrochemical measurements, ICP-MS analyses, and EC-STM observations. Pt(111) surface had higher corrosion resistance than Pt(100) and Pt(110) during potential cycles in 0.5 M H2SO4 solution, and hardly dissolved in the potential range below 1.2 V. EC-STM observations revealed the step structures became straight in the Pt(100) surface and the roughness in Pt(111) terraces gradually increases by the potential cycling in the range of 0.5 - 1.4 V. The formation of Pt islands with a higher surface energy by the potential cycling brought the increase of Pt dissolution rate in the Pt(111) surface with the number of cycle.