Surface structural transitions and active sites are identified using X-ray scattering and density functional theory.

RuO 2 catalysts exhibit record activities towards the oxygen evolution reaction (OER), which is crucial to enable efficient and sustainable energy storage. Here we examine the RuO 2 OER kinetics on rutile (110), (100), (101), and (111) orientations, finding (100) the most active. We assess the potential involvement of lattice oxygen in the OER mechanism with online

Herein we describe a combined experimental and computational study of electrochemical glycerol oxidation in acidic media on Pt(111) and Pt(100) electrodes. Our results show that glycerol oxidation is a very structure-sensitive reaction in terms of activity and, more surprisingly, in terms of selectivity. Using a combination of online HPLC and online electrochemical mass spectrometry, we show that on the Pt(111) electrode, glyceraldehyde, glyceric acid, and dihydroxyacetone are products of glycerol oxidation, while on the Pt(100) electrode, only glyceraldehyde was detected as the main product of the reaction. Density functional theory calculations show that this difference in selectivity is explained by different binding modes of dehydrogenated glycerol to the two surfaces. On Pt(111), the dehydrogenated glycerol intermediate binds to the surface through two single Pt–C bonds, yielding an enediol-like intermediate, which serves as a precursor to both glyceraldehyde and dihydroxyacetone. On Pt(100), the dehydrogenated glycerol intermediate binds to the surface through one double PtC bond, yielding glyceraldehyde as the only product. Stripping and in situ FTIR measurements show that CO is not the only strongly bound adsorbed intermediate of the oxidation of glycerol, glyceraldehyde, and dihydroxyacetone. Although the nature of this adsorbate is still unclear, this intermediate is highly resistant to oxidation and can only be removed from the Pt surface after multiple scans.

It is well known that transition metal oxides can efficiently catalyze electrochemical reactions of interest in electrolyzers and fuel cells. The question is how to describe and rationalize the variations in catalytic activity among a given class of oxides, so that known materials can be improved and new active materials be predicted. In this context, descriptor-based analyses are a powerful tool, as they help to rationalize the trends in catalytic activity through correlations with other properties of the material. Particularly, bulk thermochemistry has long been used to describe the trends in catalytic activity of oxide surfaces. Here we explain the reason for the apparent success of this descriptor on the basis of perovskite oxides and monoxides and the oxygen evolution reaction: essentially, bulk thermochemistry and surface adsorption energetics depend similarly on the number of outer electrons of the transition metal in the oxide. This correspondence applies to a wide number of transition metals and is responsible for the linear relationship between bulk and surface properties that enables the construction of volcano-type activity plots.

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Table S1: Total electronic energies for low and high spin states and relative energies of the high spin states (vs low spin states) for calculated negatively charged intermediates. * Relative values = E high spinE low spin ** The close-shell singlet does not converged probably because the lowest singlet configuration is open-shell. *** The numbers in the brackets are the spin multiplicity.

Despite being desirable high-value products of the electrochemical CO2 reduction reaction (CO2RR), alcohols are still obtained with lower selectivity compared to hydrocarbons and the reaction pathways leading to their formation are still under debate. In this joint experimental–computational work, we exploit structural sensitivity effects to elucidate the ethanol-producing active sites on Cu–Ag CO2RR tandem catalysts. Specifically, methane-selective Cu nano-octahedra (Cuoh), enclosed by (111) facets, and ethylene-selective Cu nanocubes (Cucub), enclosed by (100) facets, are mixed with CO-selective Ag nanospheres (Agsph) to form Cuoh–Ag and Cucub–Ag bimetallic catalysts. Ethanol is selectively enhanced via the *CH x –*CO coupling pathway at the terraces of Cuoh–Ag in the CO-enriched environment generated by the Agsph. Conversely, on Cucub–Ag, ethanol is selectively produced via the same pathway at the edges and corners of Cucub, while ethylene continues to be produced at the terraces. The terraces being the predominant surfaces on the catalysts, such facet dependence explains the higher ethanol-to-ethylene ratio on the Cuoh–Ag. These findings illustrate how tandem catalysis and structure-sensitive effects can be combined to obtain notable changes in the selectivity of electrochemical reactions.

We report on density functional theory (DFT)-GGA (generalized gradient approximation) computed adsorption energetics of water and the water-related fragments OH, O, and H on stepped Pt surfaces in the low coverage limit. The Pt(100) step edge as encountered on Pt(533) shows increased binding for all species studied, while the Pt(110) step edge, as found on Pt(553) shows only significantly enhanced binding for O and OH. Comparing these results to ultra high vacuum experiments reveals that DFT can explain the main experimental trends semiquantitatively.