Title: Atomistic determination of the surface structure of Cu₂O(111): experiment and theory

Abstract

Cuprous oxide (Cu₂O) is a promising catalyst for several important reactions. However, the atomic structures of defective Cu₂O surfaces, which critically affect the catalytic properties both thermodynamically and kinetically, are not unambiguously characterized. High-resolution scanning tunneling microscopy (STM), combined with density functional theory (DFT) calculations and STM simulations, has been used to determine the atomic structure of the (111) surface of a Cu₂O bulk crystal. The single crystal surface, processed by ultrahigh vacuum cleaning and oxygen annealing, shows a (1 × 1) periodicity in the low-energy electron diffraction pattern. The pristine (defect-free) Cu₂O(111) surface exhibits a lattice of protrusions with hexagonal symmetry under STM, which is attributed to the dangling bonds of the coordinatively unsaturated copper (Cu_U) atoms on the surface. Two types of surface atomic defects are also identified, including the Cu_U vacancy and the oxygen-vacancy-induced local surface restructuring. The electronic structure of this surface measured by $dI/dV$ spectroscopy shows an energy band gap of ~1.6–2.1 eV. Consistent with $dI/dV$ measurements, DFT calculations identified surface states within the electronic band gap arising from the Cu ions on the surface. Our results provide a clear picture of the pristine and defective Cu₂O(111) surface structure in addition to the formation mechanismmore » of the reconstructed surface, paving the way toward studying the site-dependent reactivity of this surface.« less

Authors:

Zhang, Rui  ^[1];

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Li, Liang  ^[1];

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Frazer, Laszlo  ^[2];

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Chang, Kelvin B. ^[3]; Poeppelmeier, Kenneth R.  ^[3];

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Chan, Maria K. Y.  ^[1];

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Guest, Jeffrey R.  ^[1]

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+ Show Author Affiliations

1. Argonne National Lab. (ANL), Argonne, IL (United States). Center for Nanoscale Materials
2. Monash Univ., Melbourne, VIC (Australia). Centre of Excellence in Exciton Science
3. Northwestern Univ., Evanston, IL (United States). Dept. of Chemistry

Publication Date:

2018-10-12

Research Org.:

Argonne National Lab. (ANL), Argonne, IL (United States)

Sponsoring Org.:

USDOE Office of Science (SC), Basic Energy Sciences (BES)

OSTI Identifier:

1484245

Alternate Identifier(s):

OSTI ID: 1479122

Grant/Contract Number:  

AC02-06CH11357; FG02-09ER16109; DE AC02-05CH11231

Resource Type:

Accepted Manuscript

Journal Name:

Physical Chemistry Chemical Physics. PCCP (Print)

Additional Journal Information:

Journal Name: Physical Chemistry Chemical Physics. PCCP (Print); Journal Volume: 20; Journal Issue: 43; Journal ID: ISSN 1463-9076

Publisher:

Royal Society of Chemistry

Country of Publication:

United States

Language:

English

Subject:

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY