Abstract
Metal oxide/water interfaces play a crucial role in many electrochemical and photocatalytic processes, such as photoelectrochemical water splitting, the creation of fuel from sunlight, and electrochemical CO2 reduction. First-principles electronic structure calculations can reveal unique insights into these processes, such as the role of the alignment of the oxide electronic energy levels with those of liquid water. An essential prerequisite for the success of such calculations is the ability to predict accurate structural models of these interfaces, which in turn requires careful experimental validation. Here we report a general, quantitative validation protocol for first-principles molecular dynamics simulations of oxide/aqueous interfaces. The approach makes direct comparisons of interfacial x-ray reflectivity (XR) signals from experimental measurements and those obtained from ab initio simulations with semilocal and van der Waals functionals. The protocol is demonstrated here for the case of the Al2O3(001)/water interface, one of the simplest oxide/water interfaces. We discuss the technical requirements needed for validation, including the choice of the density functional, the simulation cell size, and the optimal choice of the thermodynamic ensemble. Our results establish a general paradigm for the validation of structural models and interactions at solid/water interfaces derived from first-principles simulations. While there is qualitative agreement between the simulated structures and the experimental best-fit structure, direct comparisons of simulated and measured XR intensities show quantitative discrepancies that derive from both bulk regions (i.e., alumina and water) as well as the interfacial region, highlighting the need for accurate density functionals to properly describe interfacial interactions. Our results show that XR data are sensitive not only to the atomic structure (i.e., the atom locations) but also to the electron-density distributions in both the substrate and at the interface.
| Original language | English (US) |
|---|---|
| Article number | 113805 |
| Journal | Physical Review Materials |
| Volume | 4 |
| Issue number | 11 |
| DOIs | |
| State | Published - Nov 16 2020 |
Funding
This work was supported, in part, by the Midwest Integrated Center for Computational Materials (MICCoM) as part of the Computational Materials Sciences Program funded by the U.S. Department of Energy, Office of Science, Basic Energy Sciences (DOE/BES), Materials Sciences and Engineering Division (Grant No. 5J-30161-0010A). This work made use of the Center for Nanoscale Materials (CNM), the Argonne Leadership Computing Facility (ALCF), and beamline 33-ID-D of the Advanced Photon Source at Argonne National Lab (ANL), Office of Science User Facilities supported by the DOE/BES. This material is based upon work supported by Laboratory Directed Research and Development (LDRD) funding from ANL. K.J.H. gratefully acknowledges support from the U.S. Department of Defense through the National Defense Science and Engineering Graduate Fellowship (NDSEG) Program and from the Ryan Fellowship at Northwestern University International Institute of Nanotechnology. K.L.-W. acknowledges the Thomas F. and Kate Miller Jeffress Memorial Trust, Bank of America, Trustee. A.P.G. was supported by the postdoctoral fellowship from the Natural Sciences and Engineering Research Council of Canada. The submitted manuscript has been created by UChicago Argonne, LLC, Operator of Argonne National Laboratory (“Argonne”). Argonne, a U.S. Department of Energy Office of Science laboratory, is operated under Contract No. DE-AC02-06CH11357. The U.S. Government retains for itself, and others acting on its behalf, a paid-up nonexclusive, irrevocable worldwide license in said article to reproduce, prepare derivative works, distribute copies to the public, and perform publicly and display publicly, by or on behalf of the Government.
ASJC Scopus subject areas
- General Materials Science
- Physics and Astronomy (miscellaneous)
