The development of electrocatalysts for the oxygen evolution reaction (OER) is one of the principal challenges in the area of renewable energy research. Within this context, mixed-metal oxides have recently emerged as the highest performing OER catalysts. Their structural and compositional modification to further boost their activity is crucial to the wide-spread use of electrolysis technologies. In this work, we investigated a series of mixed-metal F-containing materials as OER catalysts to probe possible benefits of the high electronegativity of fluoride ions. We found that crystalline hydrated fluorides, CoFe₂F₈(H₂O)₂ and NiFe₂F₈(H₂O)₂, and amorphous oxyfluorides, NiFe₂F_4.4O_1.8 and CoFe₂F_6.6O_0.7, feature excellent activity (overpotential for 10 mA cm⁻² as low as 270 mV) and stability (extended performance for >250 hours with ∼40 mV activity loss) for the OER in alkaline electrolyte. Subsequent electroanalytical and spectroscopic characterization hinted that the electronic structure modulation conferred by the fluoride ions aided their reactivity. Finally, the best catalyst of the set, NiFe₂F_4.4O_1.8, was applied as anode in an electrolyzer comprised solely of earth-abundant materials, which carried out overall water splitting at 1.65 V at 10 mA cm⁻².

Electrochemical reduction of CO₂ (CO₂RR) driven by renewable energy has gained increasing attention for sustainable production of chemicals and fuels. Catalyst design to overcome large overpotentials and poor product selectivity remains however challenging. Sn/SnOx and In/InOx composites have been reported active for CO₂RR with high selectivity toward formate formation. In this work, the CO₂RR activity and selectivity of metal/metal oxide composite nanoparticles formed by in situ reduction of bimetallic amorphous SnInOx thin films are investigated. It is shown that during CO₂RR the amorphous SnInOx pre‐catalyst thin films are reduced in situ into Sn_1–XIn_X@In_1–YSn_YO_z core@shell nanoparticles composed of Sn‐rich SnIn alloy nanocores (with x < 0.2) surrounded by InOx‐rich bimetallic InSnOx shells (with 0.3 < y < 0.4 and z ≈ 1). The in situ formed particles catalyze the CO₂RR to formate with high faradaic efficiency (80%) and outstanding formate mass activity (437 A g_In+Sn⁻¹ @ −1.0 V vs RHE in 0.1 m KHCO₃). While extensive structural investigation during CO₂RR reveals pronounced dynamics in terms of particle size, the core@shell structure is observed for the different electrolysis conditions essayed, with high surface oxide contents favoring formate over hydrogen selectivity.

High-specific-surface-area MgF₂ was prepared by microwave-assisted solvothermal synthesis. The influences of the solvent and the magnesium precursors, and the calcination atmospheres, on the nanoparticle sizes and specific surface areas, estimated by X-Ray Powder Diffraction, N₂ sorption and TEM analyses, were investigated. Nanocrystallized (~7 nm) magnesium partially hydroxylated fluorides (MgF_2−x(OH)_x) with significant specific surface areas between 290 and 330 m²∙g⁻¹ were obtained. After activation under gaseous HF, MgF_2−x(OH)_x catalysts underwent a large decrease of both their surface area and their hydroxide, rates as shown by their ¹⁹F and ¹H solid-state NMR spectra. Expect for MgF₂ prepared from the acetate precursor, an activity of 30–32 mmol/h∙g was obtained which was about 40% higher compared with that of MgF₂ prepared using Trifluoroacetate method (21.6 mmol/h∙g).