Influence of benzene on the H{sub}(UPD) and anion adsorption on Pt(110), Pt(100) and Pt(111) electrodes in aqueous H{sub}2SO{sub}4

摘要

We present new results on the influence of C{sub}6H{sub}(6 ads) on the H{sub}(UPD) and anion adsorption on the Pt(110), Pt(100) and Pt(111) electrodes in aqueous H{sub}2SO{sub}4. We study the modification of cyclic-voltammetry (CV) profiles for Pt(110), Pt(100) and Pt(111) brought about by C{sub}6H{sub}(6 ads) and examine the inhibition of HUPD and anion adsorption. The results demonstrate that as long as C{sub}6H{sub}6 is present in aqueous H{sub}2SO{sub}4, the H{sub}(UPD) and anion adsorption is suppressed. Repetitive cycling of the C{sub}6H{sub}(6 ads)-modified Pt(110) or Pt(111) electrode in a benzene-free aqueous H{sub}2SO{sub}4 leads to a partial recovery of the CV profile characteristic of the HUPD and anion adsorption. However, cycling of the C{sub}6He{sub}(6 ads)-modified Pt(100) electrode in a benzene-free aqueous H{sub}2SO{sub}4 does not affect the CV profile, whose features point to a continuous inhibition of the H{sub}(UPD) and anion adsorption. The results indicate that the bond between C{sub}6H{sub}(6 ads) and Pt(100) is stronger than that between C{sub}6H{sub}(6 ads) and Pt(110) or Pt(111). Cathodic polarization of the C{sub}6H{sub}(6 ads)-modified Pt(110), Pt(100) and Pt(111) electrodes in benzene-free aqueous H{sub}2SO{sub}4 leads to reductive desorption of C{sub}6H{sub}6 and recovery of the CV features characteristic of clean and well-defined surfaces.