Benchmarking water adsorption on metal surfaces with ab initio molecular dynamics

Area of Science:

• Computational Materials Science
• Surface Science
• Physical Chemistry

Background:

• Solid-water interfaces are critical in natural phenomena and technological applications, notably in green transition technologies like electrocatalysis.
• Density functional theory (DFT) is the standard for atomistic simulations of electrolyte-electrode interfaces, necessitating validation for solid/water interactions.
• Accurate simulation setups are essential to prevent systematic errors in understanding interfacial processes.

Purpose of the Study:

• To develop and apply a rigorous protocol for benchmarking DFT's simulation of water adsorption/desorption energetics on metallic surfaces.
• To evaluate the performance of common exchange-correlation functionals (PBE-D3, RPBE-D3, BEEF-vdW) for water-metal interactions.
• To provide guidance for future DFT simulations of solvated solid interfaces by assessing systematic errors.

Main Methods:

• Benchmarking DFT calculations against experimental data: temperature programmed desorption, single crystal adsorption calorimetry, and thermal energy atom scattering.
• Screening DFT quality on various transition metal surfaces using PBE-D3, RPBE-D3, and BEEF-vdW exchange-correlation functionals.
• Analyzing water adsorption strengths and relating variations to water-metal and water-water interactions.

Main Results:

• All tested functionals (PBE-D3, RPBE-D3, BEEF-vdW) capture the pseudo-zeroth order desorption of water.
• RPBE-D3 and BEEF-vdW functionals yield more accurate water adsorption strengths compared to experimental data.
• The PBE-D3 functional systematically overbinds near-surface water, leading to potential inaccuracies in simulations.

Conclusions:

• The choice of exchange-correlation functional significantly impacts the accuracy of simulated water adsorption energetics at solid-water interfaces.
• RPBE-D3 and BEEF-vdW are recommended for more reliable DFT simulations of water-metal interactions.
• This study offers atomistic insights into water adsorption equilibrium and provides a framework for error assessment in DFT simulations.