Item

Abstract

It is demonstrated by a combined electrochemical, LEED, RHEED and AES study that the reconstructed Pt(100) surface is stable in aqueous electrolytes under certain potential conditions. The reconstructed Pt(100) surface has higher stability ranges than Au(100) in both 0.01 M H₂SO₄ (0.6 V) and 0.01 M HClO₄ (1.1 V). The reconstructed Au(100) surface is uniformly transformed into the (1×1) phase in both H₂SO₄ and HClO₄ solutions, whereas with Pt(100) this happens only in H₄SO₂ at 1.0 V. The latter surface is not uniformly deconstructed in 0.01 M HClO₄, even up to 1.1 V. The stability range is drastically reduced in the presence of Cl⁻ (0.01 mM), and the (5×1) phase does not survive in a 0.1 mM HCl solution. Electrochemical annealing such as at Au in the presence of Cl⁻ was not found at Pt(100)-(1×1) after lifting of reconstruction, whereas a well-ordered array of <011> steps/rows with a mean spacing of 2.8 nm (2×5-fold periodicity of a reconstructed Pt(100)) developed. This is an intermediate structure formed by the Pt phase transition (5×1)→(1×1) in electrolytes.