Water Adsorption and Dissociation at Metal-Supported Ceria Thin Films: Thickness and Interface-Proximity Effects Studied with DFT+U Calculations

Abstract

The chemistry of several catalytic processes can be controlled by tuning metal−oxide interfaces, as demonstrated by fundamental studies on inverse model catalysts. We investigate the effects of the metal−oxide interface on the surface reactivity of ceria (CeO 2 ) thin films supported by a copper metal surface. Our density functional theory (DFT+U) calculations reveal that the interface has impact on the surface water adsorption and dissociation when the thickness of the ceria film is below ≈9 Å. On thinner films, the energetics of adsorption and dissociation display a significant variation, which arises from a combination of thickness and interface-proximity effects, and which we rationalize in terms of charge-density response at the adsorbate-oxide and oxide-metal interfaces. The adsorption energy is maximized for film thicknesses of 5.5 Å (corresponding to two O−Ce−O trilayers), while thinner films affect primarily the relative stability between molecular, semidissociated, and dissociated water adsorption. These results provide useful insights into the effect of low-dimensional ceria species in Cu/CeO 2 catalysts.

Investigations of water/oxide interfaces by molecular dynamics simulations

“…One example we will discuss in this review is the spontaneous water dissociation at the water/CeO 2 (111) interface 177 . Farnesi Camellone et al designed a CeO 2 surface with a Pt 6 cluster on it.…”

“…176 One example we will discuss in this review is the spontaneous water dissociation at the water/CeO 2 (111) interface. 177 Farnesi Camellone et al designed a CeO 2 surface with a Pt 6 cluster on it. They found that after a proton transfer to the CeO 2 surface, the resulting OH À binds to a Pt site instead of the Ce site.…”

Oxide-based nanomaterials for fuel cell catalysis: the interplay between supported single Pt atoms and particles

“…101,141,142 DFT calculations were employed to investigate water dissociation at the ceria (111) surface 143 and at the ceria/liquid interface 144 as well as to elucidate the charge transfers between Pt particles and the ceria support resulting from water dissociation. The influence of the aqueous environment on the reaction mechanism, thermodynamics and kinetics was investigated by means of ab initio molecular dynamics (MD) simulations.…”

Water Adsorption and Dissociation on Ceria‐Supported Single‐Atom Catalysts: A First‐Principles DFT+U Investigation

“…[24,25] Significantp rogress has been achieved in understandingw ater adsorption behavior on cleanC eO 2 (111)s urfaces. [26][27][28][29][30][31][32][33][34][35][36][37][38] For example, noncontact atomic force microscopy (nc-AFM)e xperiments by Gritschneder et al [29] and the lowtemperature scanning tunneling microscopy (STM) experiments by Grinter et al [31] suggested that water did not undergo complete dissociation on clean cerias urfaces. The calculations showed molecular water adsorption on the top site of surfaceC ea toms was the most thermodynamically stable structure.…”

“…The CeO 2 (111) surface is the most thermodynamically stable surface . Significant progress has been achieved in understanding water adsorption behavior on clean CeO 2 (111) surfaces . For example, noncontact atomic force microscopy (nc‐AFM) experiments by Gritschneder et al .…”