The Critical Role of Thermal Fluctuations for Electrocatalytic Metal Surface Properties and CO Binding Trends

TL;DR

This study demonstrates that including thermal fluctuations in DFT calculations improves predictions of metal surface properties and CO binding trends, aligning theory more closely with experimental observations in electrocatalysis.

Contribution

Introducing thermal fluctuations via statistical mechanical ensembles into DFT calculations enhances the accuracy of surface strain and CO binding predictions on metal catalysts.

Findings

Thermal fluctuations improve DFT predictions of metal surface strain trends.

Thermally induced surface distortions explain site preferences for CO binding.

Finite temperature effects lead to mixed chemisorbed and physisorbed CO states on weakly binding metals.

Abstract

This work addresses a longstanding theoretical discrepancy using Density Functional Theory (DFT) with experimental observations of CO binding trends on electrocatalytically relevant metals for the CO2 reduction reaction (CO2RR). By introducing thermal fluctuations using appropriate statistical mechanical NVT and NPT ensembles, we show that DFT with universal dispersion interactions yields qualitatively better metal surface strain trends and CO binding energetics, consistently predicts the correct site preference for all metals due to thermally induced surface distortions that preferentially exposes the undercoordinated atop site for Cu(111) and Pt(111), and for the weak binding Ag(111) and Au(111) surfaces at finite temperatures shows CO-metal interactions that are a mixture of chemisorbed and physisorbed species. This study better places theory as an equal partner to experimental heterogeneous catalysis by demonstrating the need to fully account for finite temperature fluctuations to make contact with surface science experiments.