The carbon–carbon coupling via electrochemical reduction of carbon dioxide represents the biggest challenge for using this route as platform for chemicals synthesis. Here we show that nanostructured iron (III) oxyhydroxide on nitrogen-doped carbon enables high Faraday efficiency (97.4%) and selectivity to acetic acid (61%) at very-low potential (−0.5 V vs silver/silver chloride). Using a combination of electron microscopy, operando X-ray spectroscopy techniques and density functional theory simulations, we correlate the activity to acetic acid at this potential to the formation of nitrogen-coordinated iron (II) sites as single atoms or polyatomic species at the interface between iron oxyhydroxide and the nitrogen-doped carbon. The evolution of hydrogen is correlated to the formation of metallic iron and observed as dominant reaction path over iron oxyhydroxide on oxygen-doped carbon in the overall range of negative potential investigated, whereas over iron oxyhydroxide on nitrogen-doped carbon it becomes important only at more negative potentials.

Synergistic effects between alkali-free hydrotalcites and gold nanoparticles afford efficient heterogeneous catalysts for the cascade oxidation of 5-HMF to 2,5-FDCA.

The production of hydrogen at a large scale by the environmentally-friendly electrolysis process is currently hampered by the slow kinetics of the oxygen evolution reaction (OER). We report a solid electrocatalyst α-Li₂IrO₃ which upon oxidation/delithiation chemically reacts with water to form a hydrated birnessite phase, the OER activity of which is five times greater than its non-reacted counterpart. This reaction enlists a bulk redox process during which hydrated potassium ions from the alkaline electrolyte are inserted into the structure while water is oxidized and oxygen evolved. This singular charge balance process for which the electrocatalyst is solid but the reaction is homogeneous in nature allows stabilizing the surface of the catalyst while ensuring stable OER performances, thus breaking the activity/stability tradeoff normally encountered for OER catalysts.

A series of MoO_x-modified Fe₂O₃ catalysts have been prepared in an attempt to make core–shell oxidic materials of the type MoO_x/Fe₂O₃. It is conclusively shown that for three monolayers of Mo dosed, the Mo stays in the surface region, even after annealing to high temperature. It is only when the material is annealed above 400 °C that it reacts with the iron oxide. We show by a combination of methods, and especially by XAFS, that at temperatures above 400 °C, most of the Mo converts to Fe₂(MoO₄)₃, with Mo in a tetrahedral structure, whereas below that temperature, nanocrystalline MoO₃ is present in the sample; however, the active catalysts have an octahedral MoO_x layer at the surface even after calcination to 600 °C. This surface layer appears to be present at all temperatures between 300 and 600 °C, and it is the nanoparticles of MoO₃ that are present at the lower temperature that react to form ferric molybdate, which underlies this surface layer. It is the MoO_x layer on the Fe₂(MoO₄)₃ underlayer that makes the surface active and selective for formaldehyde synthesis, whereas the iron oxide surface itself is a combustor. The material is both activated and improved in selectivity due to the dominance of the methoxy species on the Mo-doped material, as opposed to the much more stable formate, which is the main intermediate on Fe₂O₃.