Converting carbon dioxide (CO₂) into liquid fuels and synthesis gas is a world-wide priority. But there is no experimental information on the initial atomic level events for CO₂ electroreduction on the metal catalysts to provide the basis for developing improved catalysts. Here we combine ambient pressure X-ray photoelectron spectroscopy with quantum mechanics to examine the processes as Ag is exposed to CO₂ both alone and in the presence of H₂O at 298 K. We find that CO₂ reacts with surface O on Ag to form a chemisorbed species (O = CO₂^δ−). Adding H₂O and CO₂ then leads to up to four water attaching on O = CO₂^δ− and two water attaching on chemisorbed (b-)CO₂. On Ag we find a much more favorable mechanism involving the O = CO₂^δ− compared to that involving b-CO₂ on Cu. Each metal surface modifies the gas-catalyst interactions, providing a basis for tuning CO₂ adsorption behavior to facilitate selective product formations.

The roles of grain boundaries and twin boundaries in mechanical properties are well understood for metals and alloys. However, for covalent solids, their roles in deformation response to applied stress are not established. Here we characterize the nanotwins in boron suboxide (B₆O) with twin boundaries along the "Equation missing"<!-- image only, no MathML or LaTex --> planes using both scanning transmission electron microscopy and quantum mechanics. Then, we use quantum mechanics to determine the deformation mechanism for perfect and twinned B₆O crystals for both pure shear and biaxial shear deformations. Quantum mechanics suggests that amorphous bands nucleate preferentially at the twin boundaries in B₆O because the twinned structure has a lower maximum shear strength by 7.5% compared with perfect structure. These results, which are supported by experimental observations of the coordinated existence of nanotwins and amorphous shear bands in B₆O, provide a plausible atomistic explanation for the influence of nanotwins on the deformation behaviour of superhard ceramics.

Ambient pressure XPS has demonstrated its great potential in probing the solid/liquid interface, which is a central piece in electrocatalytic, corrosion, and energy storage systems. Despite the advantage of ambient pressure XPS being a surface sensitive characterization technique, the ability of differentiating the surface adsorbed species (∼Å scale) and bulk electrolyte (∼10 nm scale) in the spectrum depends on the delicate balance between bulk solution concentration (C), surface coverage (θ), bulk liquid layer thickness (L), and inelastic mean free path (λ) as a function of photon energy. By investigating a model system of gold dissolving in a bromide solution, the connection between theoretical prediction at the atomic resolution and macroscopic observable spectrum is established.