On the structural transformation of the reconstructed Pt(100) in electrolyte solutions

It is demonstrated by a combined electrochemical, LEED, RHEED and AES study that the reconstructed Pt(100) surface is stable in aqueous electrolytes u nder certain potential conditions. The reconstructed Pt(100) surface has hi gher stability ranges than Au(100) in both 0.01 M H2SO, (0.6 V) and 0.01 M HClO4 (1.1 V). The reconstructed Au(100) surface is uniformly transformed i nto the (1 x 1) phase in both H2SO4 and HClO4 solutions, whereas with Pt(10 0) this happens only in H2SO4 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 dr astically reduced in the presence of Cl- (0.01 mM), and the (5 x 1) phase d oes 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 x 1) after liftin g of reconstruction, whereas a well-ordered array of [011] steps/rows with a mean spacing of 2.8 nm (2 x 5-fold periodicity of a reconstructed Pt(100) ) developed. This is an intermediate structure formed by the Pt phase trans ition (5 x 1)-->(1 x 1) in electrolytes. (C) 1999 Elsevier Science B.V. All rights reserved.