Determining the adsorption energies of small molecules with the intrinsic properties of adsorbates and substrates.

Adsorption is essential for many processes on surfaces; therefore, an accurate prediction of adsorption properties is demanded from both fundamental and technological points of view. Particularly, identifying the intrinsic determinants of adsorption energy has been a long-term goal in surface science. Herein, we propose a predictive model for quantitative determination of the adsorption energies of small molecules on metallic materials and oxides, by using a linear combination of the valence and electronegativity of surface atoms and the coordination of active sites, with the corresponding prefactors determined by the valence of adsorbates. This model quantifies the effect of the intrinsic properties of adsorbates and substrates on adsorbate-substrate bonding, derives naturally the well-known adsorption-energy scaling relations, and accounts for the efficiency and limitation of engineering the adsorption energy and reaction energy. All involved parameters are predictable and thus allow the rapid rational design of materials with optimal adsorption properties.

Different effects of water molecules on CO oxidation with different reaction mechanisms.

The effects of water molecules (promotion/prohibition) on CO oxidation remain debated. Herein, using density functional theory calculations, we demonstrate that water molecules can facilitate the CO + O/O2 oxidation process, but prohibit the CO + OH oxidation process, which is consistent with the experimental finding that water molecules have two distinct effects on CO oxidation. For the CO + O/O2 oxidation mechanisms, we find that the reactants were pushed towards each other due to the steric effect of the water molecules, which decreases the reaction barriers and promotes the CO + O/O2 oxidation process. For the CO + OH oxidation mechanisms, water molecules increase the stability of the COOH* intermeditae by H-bonds and van der Waals forces, which increase the barriers of the COOH* transformation process and the COOH*-tra dissociation process, and prohibit the CO + OH oxidation process. These results clarify the different effects of water molecules on CO oxidation and shed light on catalyst usage in the CO oxidation industry.

Mechanistic Insights into the Unique Role of Copper in CO2 Electroreduction Reactions.

Cu demonstrates a unique capability towards CO2 electroreduction that can close the anthropogenic carbon cycle; however, its reaction mechanism remains elusive, owing to the obscurity of the solid-liquid interface on Cu surfaces where electrochemical reactions occur. Using a genetic algorithm method in addition to density functional theory, we explicitly identify the configuration of a water bilayer on Cu(2 1 1) and build electrochemical models. These enable us to reveal a mechanistic picture for CO2 electroreduction, finding the key intermediates CCO* for the C2 H4 pathway and CH* for the CH4 pathway, which rationalize a series of experimental observations. Furthermore, we find that the interplay between the Cu surfaces, carbon monomers, and water network (but not the binding of CO*) essentially determine the unique capability of Cu towards CO2 electroreduction, proposing a new and effective descriptor for exploiting optimal catalysts.