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The design of active and durable catalysts for the H 2 O/O 2 interconversion is one of the major challenges of electrocatalysis for renewable energy. The oxygen evolution reaction (OER) is catalyzed by SrRuO 3 with low potentials (ca. 1.35 V RHE ), but the catalyst’s durability is insufficient. Here we show that Na doping enhances both activity and durability in acid media. DFT reveals that whereas SrRuO 3 binds reaction intermediates too strongly, Na doping of ~0.125 leads to nearly optimal OER activity. Na doping increases the oxidation state of Ru, thereby displacing positively O p-band and Ru d-band centers, weakening Ru-adsorbate bonds. The enhanced durability of Na-doped perovskites is concomitant with the stabilization of Ru centers with slightly higher oxidation states, higher dissolution potentials, lower surface energy and less distorted RuO 6 octahedra. These results illustrate how high OER activity and durability can be simultaneously engineered by chemical doping of perovskites. While water splitting may afford a renewable means to store energy in chemical bonds, water oxidation catalysts suffer from poor stabilities in acidic media. Here, authors show sodium doping of strontium ruthenate to improve the catalytic durability while maintaining a high O 2 evolution activity.

Proton exchange membrane water electrolysis is a promising technology to produce green hydrogen from renewables, as it can efficiently achieve high current densities. Lowering iridium amount in oxygen evolution reaction electrocatalysts is critical for achieving cost-effective production of green hydrogen. In this work, we develop catalysts from Ir double perovskites. Sr 2 CaIrO 6 achieves 10 mA cm −2 at only 1.48 V. The surface of the perovskite reconstructs when immersed in an acidic electrolyte and during the first catalytic cycles, resulting in a stable surface conformed by short-range order edge-sharing IrO 6 octahedra arranged in an open structure responsible for the high performance. A proton exchange membrane water electrolysis cell is developed with Sr 2 CaIrO 6 as anode and low Ir loading (0.4 mg Ir cm −2 ). The cell achieves 2.40 V at 6 A cm −2 (overload) and no loss in performance at a constant 2 A cm −2 (nominal load). Thus, reducing Ir use without compromising efficiency and lifetime. While water splitting offers a renewable means to produce H 2 fuel, most electrolyzers rely on scarce elements to function. Here, authors study low-content Iridium catalysts derived from mixed oxides for proton exchange membrane water electrolysis anodes without compromising activity and durability.

The production of green hydrogen in water electrolyzers is limited by the oxygen evolution reaction (OER). State-of-the-art electrocatalysts are based on Ir. Ru electrocatalysts are a suitable alternative provided their performance is improved. Here we show that low-Ru-content pyrochlores (R 2 MnRuO 7 , R = Y, Tb and Dy) display high activity and durability for the OER in acidic media. Y 2 MnRuO 7 is the most stable catalyst, displaying 1.5 V at 10 mA cm −2 for 40 h, or 5000 cycles up to 1.7 V. Computational and experimental results show that the high performance is owed to Ru sites embedded in RuMnO x surface layers. A water electrolyser with Y 2 MnRuO 7 (with only 0.2 mg Ru cm −2 ) reaches 1 A cm −2 at 1.75 V, remaining stable at 200 mA cm −2 for more than 24 h. These results encourage further investigation on Ru catalysts in which a partial replacement of Ru by inexpensive cations can enhance the OER performance. Ru-pyrochlores find their way as alternative anodes of PEM water electrolyzers, and their high performance is owing to Ru sites embedded in RuMnO x surface layers. Here, a water electrolyser with Y 2 MnRuO 7 and only 0.2 mgRu cm −2 has been tested with significant durability.

Dimethyl ether (DME) is an advanced second-generation biofuel produced via methanol dehydration over acid catalysts such as γ-Al 2 O 3 , at temperatures above 240 °C and pressures above 10 bar. Heteropolyacids such as tungstosilicic acid (HSiW) are Brønsted acid catalysts with higher DME production rates than γ-Al 2 O 3 , especially at low temperatures (140–180 °C). In this work, we show that the performance of supported HSiW for the production of DME is strongly affected by the nature of the support. TiO 2 and SiO 2 supported HSiW display the highest DME production rates of ca. 50 mmol DME /h/g HSiW . Characterization of acid sites via 1 H-NMR, NH 3 -isotherms and NH 3 -adsrobed DRIFT reveal that HSiW/X have Brønsted acid sites, HSiW/TiO 2 showing more and stronger sites, being the most active catalyst. Methanol production increases with T until 200 °C where a rapid decay in methanol conversion is observed. This effect is not irreversible, and methanol conversion increases to ca. 90% by increasing reaction pressure to 10 bar, with DME being the only product detected at all reaction conditions studied in this work. The loss of catalytic activity with the increasing temperature and its increasing with reaction pressure accounts to the degree of contribution of the pseudo-liquid catalysis under the reaction conditions studied.

Mesoporous silica are inorganic materials, which are formed by the condensation of sodium silicate or silicon alkoxides around an ordered surfactant used as template [...].Mesoporous silica are inorganic materials, which are formed by the condensation of sodium silicate or silicon alkoxides around an ordered surfactant used as template [...].

The demand of green hydrogen, that is, the hydrogen produced from water electrolysis, is expected to increase dramatically in the coming years. State‐of‐the‐art proton exchange membrane water electrolysis (PEMWE) uses high loadings of platinum group metals, such as Pt in the electrode where hydrogen is produced. Alternative electrodes based on phosphides, sulfides, nitrides, and other low‐cost alternatives are under investigation. Herein, a simple process for the preparation of RuP electrodes with high activity for the hydrogen evolution reaction (HER) in acidic electrolyte is described. A straightforward one‐pot synthesis that yields RuP nanoparticles with fine‐tuned composition and stoichiometry is presented, as determined by multiple characterization techniques, including lab‐ and synchrotron‐based experiments and theoretical modeling. The RuP nanoparticles exhibit a high activity of 10 mA cm−2 at 36 mV overpotential and a Tafel slope of 30 mV dec−1, which is comparable to Pt/C. Moreover, a RuP catalyst‐coated membrane (CCM) with a low Ru loading of 0.6 mgRu cm−2 is produced and tested in a PEMWE cell configuration, yielding 1.7 A cm−2 at 2 V. Herein, RuP with high activity for the hydrogen evolution reaction in acidic electrolyte comparable to state‐of‐the‐art Pt‐based catalyst is reported. A pure, stoichiometric RuP is synthesized by a simple one‐pot approach. RuP exhibits an impressive low overpotential of 36 mV at 10 mA cm−2 in rotating disk electrode. The high activity is demonstrated in proton exchange membrane water electrolysis with a low Ru loading of 0.6 mgRu cm−2.

The development of efficient, stable, and cost‐effective bifunctional electrocatalysts, particularly those based on earth‐abundant elements, is essential for the advancement and large‐scale deployment of rechargeable zinc–air batteries (ZABs). In this study, we report the synthesis and electrochemical evaluation of FeMnOx–graphene composites as bifunctional catalysts for the oxygen reduction (ORR) and oxygen evolution reactions (OER). Three catalysts were prepared using a patented process by Gnanomat SL with different graphene nanoplatelets of different physicochemical properties and characterized through XRD, TEM, STEM‐EDS, XPS, TGA, and BET analyses. All samples exhibited poor crystallinity and, according to XPS analysis, showed similar surface phases attributed to Fe2O3 or Fe3+ oxyhydroxide species and Mn3O4. Meanwhile, the graphene support influenced the final surface area and oxide dispersion of the composite. Electrochemical testing using a three‐electrode system revealed that FeMn‐graphene composites, synthesized with high‐surface‐area graphene, exhibit promising bifunctional activity for both the ORR and OER. Full‐cell ZAB testing confirmed improved charge‐discharge performance and excellent cycling stability over 500 h at 10 mA cm⁻2. These findings highlight the potential of FeMnOx–graphene composites as sustainable and efficient bifunctional air electrodes, providing an attractive alternative to bifunctional catalysts based on critical elements like Co. FeMnOx–graphene composites, synthesized via a patented method developed by Gnanomat SL, exhibit outstanding bifunctional catalytic activity and long‐term stability in Zn–air battery air electrodes. This strategy offers a sustainable and cost‐effective alternative to cobalt‐based catalysts for advanced energy storage systems.

Ni, Fe‐based nitrides have been widely studied for the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) in alkaline media, displaying electrocatalytic activities similar to Pt and other noble metal electrocatalysts. The incorporation of small amounts of Mo or W on these Ni, Fe‐based nitrides is expected to have a significant effect on the electrocatalytic performance of these materials, especially for the HER activity. In this work, transition metal nitrides (TMNs) with the empirical formula Ni1+xFe3−x−yAyN (A = Mo, W), were obtained in two steps: synthesis of the transition metal oxide precursors by an easy, one‐pot sol–gel polymerization method followed by nitridation under ammonia atmosphere to obtain the final TMNs. Their HER and OER catalytic performances in alkaline electrolyte (0.1 M KOH solution) were studied and it was observed that the incorporation of small quantities of Mo or W in these Ni, Fe‐based nitrides (Ni1+xFe3−x−yAyN, where y = 0.1) results in improved HER and OER activities, especially in the TMN that contains W (i.e., Ni1+xFe2.9−xW0.1N), where the overpotentials were 348 mV for OER and 269 mV for HER. These values are lower than those obtained for Ni1+xFe3−xN, which are 395 mV for OER and 368 mV for HER. The incorporation of small amounts of Mo or W in the structure of Ni1+xFe3−xN resulted in better electrocatalytic activities for hydrogen and oxygen production, especially in the case of the nitride that contains W (Ni1+xFe2.9−xW0.1N), which presents the best electrocatalytic performance and also shows the best electrochemical stability.

Four oxyfluorides of the title series (x = 0.00, 0.25, 0.50, 0.75) have been stabilized by topotactic treatment of perovskite precursors Sr1−xBaxFeO3−δ prepared by soft-chemistry procedures, yielding reactive materials that can easily incorporate a substantial amount of F atoms at moderate temperatures, thus avoiding the stabilization of competitive SrF2 and BaF2 parasitic phases. XRD and Neutron Powder Diffraction (NPD) measurements assess the phase purity and yield distinct features concerning the unit cell parameters’ variation, the Sr and Ba distribution, the stoichiometry of the anionic sublattice and the anisotropic displacement factors for O and F atoms. The four oxyfluorides are confirmed to be cubic in all of the compositional range, the unit cell parameters displaying Vergard’s law. All of the samples are magnetically ordered above room temperature; the magnetic structure is always G-type antiferromagnetic, as shown from NPD data. The ordered magnetic moments are substantially high, around 3.5 μB, even at room temperature (RT). Temperature-dependent Mössbauer data allow identifying Fe3+ in all of the samples, thus confirming the Sr1−xBaxFeO2F stoichiometry. The fit of the magnetic hyperfine field vs. temperature curve yields magnetic ordering TN temperatures between 740 K (x = 0.00) and 683 K (x = 0.75). These temperatures are substantially higher than those reported before for some of the samples, assessing for stronger Fe-Fe superexchange interactions for these specimens prepared by fluorination of citrate precursors in mild conditions.

Total control over the electronic spin relaxation in molecular nanomagnets is the ultimate goal in the design of new molecules with evermore realizable applications in spin-based devices. For single-ion lanthanide systems, with strong spin–orbit coupling, the potential applications are linked to the energetic structure of the crystal field levels and quantum tunneling within the ground state. Structural engineering of the timescale of these tunneling events via appropriate design of crystal fields represents a fundamental challenge for the synthetic chemist, since tunnel splittings are expected to be suppressed by crystal field environments with sufficiently high-order symmetry. Here, we report the long missing study of the effect of a non-linear ( C 4 ) to pseudo-linear ( D 4d ) change in crystal field symmetry in an otherwise chemically unaltered dysprosium complex. From a purely experimental study of crystal field levels and electronic spin dynamics at milliKelvin temperatures, we demonstrate the ensuing threefold reduction of the tunnel splitting. Suppression of quantum tunneling in molecular magnets is key for their magnetic behaviours to be exploitable. Here, the authors show that tuning the geometry of lanthanide single-ion magnets leads to a suppression of the quantum tunneling, finding a three-fold reduction of the tunnel splitting upon changing the crystal field symmetry.