Initial Steps in Forming the Electrode–Electrolyte Interface: H2O Adsorption and Complex Formation on the Ag(111) Surface from Combining Quantum Mechanics Calculations and Ambient Pressure X-ray Photoelectron Spectroscopy

• Published in: Journal of the American Chemical Society Vol. 141; no. 17; pp. 6946 - 6954
• Main Authors: Qian, Jin, Ye, Yifan, Yang, Hao, Yano, Junko, Crumlin, Ethan J
• Format: Journal Article
• Language: English
• Published: United States American Chemical Society 01.05.2019; American Chemical Society (ACS)
• Subjects: adsorption; Free energy; INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY; kinetics; thin films; x-ray photoelectron spectroscopy
• ISSN: 0002-7863; 1520-5126
• DOI: 10.1021/jacs.8b13672

The interaction of water with metal surfaces is at the heart of electrocatalysis. But there remain enormous uncertainties about the atomistic interactions at the electrode–electrolyte interface (EEI). As the first step toward an understanding of the EEI, we report here the details of the initial steps of H2O adsorption and complex formation on a Ag(111) surface, based on coupling quantum mechanics (QM) and ambient-pressure X-ray photoelectron spectroscopy (APXPS) experiments. We find a close and direct comparison between simulation and experiment, validated under various isotherm and isobar conditions. We identify five observable oxygen-containing species whose concentrations depend sensitively on temperature and pressure: chemisorbed O* and OH*, H2O* stabilized by hydrogen bond interactions with OH* or O*, and multilayer H2O*. We identify the species experimentally by their O 1s core-level shift that we calculate with QM along with the structures and free energies as a function of temperature and pressure. This leads to a chemical reaction network (CRN) that we use to predict the time evolution of their concentrations over a wide range of temperature (298–798 K) and pressure conditions (10–6–1 Torr), which agree well with the populations determined from APXPS. This multistep simulation CRN protocol should be useful for other heterogeneous catalytic systems.