TY - JOUR
T1 - OH Binding Energy as a Universal Descriptor of the Potential of Zero Charge on Transition Metal Surfaces
AU - Kelly, Sara R.
AU - Heenen, Hendrik H.
AU - Govindarajan, Nitish
AU - Chan, Karen
AU - Nørskov, Jens K.
PY - 2022
Y1 - 2022
N2 - The potential of zero charge (UPZC) is an important quantity of metal-water interfaces that are central in many electrochemical applications. In this work, we use ab initio molecular dynamics (AIMD) simulations to study a large number of (111), (100), (0001), and (211) and overlayers of transition metal-water interfaces to identify simple descriptors to predict their UPZC. We find a good correlation between water coverage and the work function reduction Δφ which is defined by the difference of the work function in a vacuum and in the presence of water. Furthermore, we determine the vacuum binding energies of H2O and *OH species as good descriptors for the prediction of water coverage and thereby of Δφ. Our insights unify different facet geometries and mixed metal surfaces and thereby generalize recent observations. We further present a scheme to predict UPZC based only on the *OH binding and the vacuum work function estimated from static DFT calculations. This formalism is applicable to all investigated metals and mixed metal surfaces including terrace and step geometries and does not require expensive AIMD simulations. To evaluate physical influences to UPZC, we decompose Δφ into its orientational (Δφorient) and electronic (Δφel) component. We find Δφorient to be a facet-dependent property and a major contributor to Δφ on (211) surfaces, while Δφel strongly depends on the metal identity.
AB - The potential of zero charge (UPZC) is an important quantity of metal-water interfaces that are central in many electrochemical applications. In this work, we use ab initio molecular dynamics (AIMD) simulations to study a large number of (111), (100), (0001), and (211) and overlayers of transition metal-water interfaces to identify simple descriptors to predict their UPZC. We find a good correlation between water coverage and the work function reduction Δφ which is defined by the difference of the work function in a vacuum and in the presence of water. Furthermore, we determine the vacuum binding energies of H2O and *OH species as good descriptors for the prediction of water coverage and thereby of Δφ. Our insights unify different facet geometries and mixed metal surfaces and thereby generalize recent observations. We further present a scheme to predict UPZC based only on the *OH binding and the vacuum work function estimated from static DFT calculations. This formalism is applicable to all investigated metals and mixed metal surfaces including terrace and step geometries and does not require expensive AIMD simulations. To evaluate physical influences to UPZC, we decompose Δφ into its orientational (Δφorient) and electronic (Δφel) component. We find Δφorient to be a facet-dependent property and a major contributor to Δφ on (211) surfaces, while Δφel strongly depends on the metal identity.
U2 - 10.1021/acs.jpcc.1c10362
DO - 10.1021/acs.jpcc.1c10362
M3 - Journal article
SN - 1932-7447
VL - 126
SP - 5521
EP - 5528
JO - Journal of Physical Chemistry C
JF - Journal of Physical Chemistry C
IS - 12
ER -