Growth of Stable Surface Oxides on Pt(111) at Near‐Ambient Pressures

Abstract

Detailed knowledge of the structure and degree of oxidation of platinum surfaces under operando conditions is essential for understanding catalytic performance. However, experimental investigations of platinum surface oxides have been hampered by technical limitations, preventing in situ investigations at relevant pressures. As a result, the time-dependent evolution of oxide formation has only received superficial treatment. In addition, the amorphous structures of many surface oxides have hindered realistic theoretical studies. Using near-ambient pressure X-ray photoelectron spectroscopy (NAP-XPS) we show that a time scale of hours (t≥4 h) is required for the formation of platinum surface oxides. These experimental observations are consistent with ReaxFF grand canonical Monte Carlo (ReaxFF-GCMC) calculations, predicting the structures and coverages of stable, amorphous surface oxides at temperatures between 430-680 K and an O partial pressure of 1 mbar.

PtCo/rGO nano-anode catalyst: enhanced power density with reduced methanol crossover in direct methanol fuel cell

“…Fitting components for Pt 4f 7/2 of commercial Pt/C appear at 71. 35,72.05, and 73.95 eV, and these can be assigned to metallic Pt [Pt (0)] and higher valence states of Pt [Pt(II) and Pt(IV)], respectively [25][26][27]. For Pt 4f 7/2 of PtCo(1:9)/rGO, Pt (0)-, Pt(II)-, and Pt(IV)related peaks appear at 71.55, 72.3, and 74.35 eV, respectively, and thus exhibit 0.2 eV positive BE shift compared to commercial Pt/C sample.…”

Cottrell Scholars: S. Ardo, A. E. Hargrove, N. B. Shustova, Y. Surendranath / TREE Awards: S. M. Cohen, D. S. Ginger / Kołos‐Medaille: W. Thiel / Welch Award: H.‐P. Steinrück / Sächsischer Verdienstorden: A. Beck‐Sickinger, E. Hey‐Hawkins, B. Voit

“…Steinrück wurde in dieser Rubrik vorgestellt, als er in die Leopoldina aufgenommen worden war . Er ist Coautor einer in der Angewandten Chemie erschienenen Arbeit über das Wachstum stabiler Oxide auf Platin(111)‐Oberflächen …”

Catalytic Oxidation of CO on a Curved Pt(111) Surface: Simultaneous Ignition at All Facets Through a Transient CO-O Complex

“…37,[55][56][57][58][59] However, the high oxygen dissociation probability at steps may be ineffective due to an equally low CO oxidation rate, making it a priori unclear whether steps are beneficial for the catalytic efficiency of the surface. 55 Only a few experiments have been done on vicinal surfaces at millibar pressures, which prove the presence of structural instabilities 42,60 and volatile oxides, 52 pointing to diverse reaction mechanisms and structural/chemical interplay. The role of steps can be better rationalized through a simultaneous analysis of different surface planes, e.g., using cylindrical crystals.…”