Instituto de Microscopía Electrónica y Materiales IMEYMAT

Copper(I) Oxo Species in Cu/ZnO Catalysts and Its Role in the Methanol Synthesis from CO2 Hydrogenation

Thu, 01 Jan 2026 00:00:00 GMT

Copper(I) Oxo Species in Cu/ZnO Catalysts and Its Role in the Methanol Synthesis from CO2 Hydrogenation Soriano, J.; Fo, Y.; Gómez, D.; López Nieto, J.M.; Roy, A.; Manzorro Ureba, Ramón; Arenal, R.; Calvino Gámez, José Juan; Song, W.; Concepción, P. This study reveals the presence of low-atomicity copper(I) oxo clusters strongly anchored to ZnO in commercial-type Cu/ZnO catalysts that, coexisting with metallic copper nanoparticles, play a critical role in CO2 hydrogenation. Their detection is challenging because metallic copper nanoparticles dominate the catalyst surface and these clusters appear in low amounts. Nevertheless, definitive evidence of their existence comes from the combination of in situ Raman spectroscopy, temperature-programmed CO surface reaction (TPSR-CO), time-resolved kinetic studies, and advance microscopy studies (STEM-XEDS and STEM-EELS). Catalytic studies combined with density functional theory (DFT) calculations demonstrate its critical role in methanol production and their size-dependent contribution to the total activity compared to traditional Cu-ZnO interfacial sites. According to DFT studies, CO2 adsorption is significantly more favorable on small Cu14O7 and Cu32O16 clusters than on extended Cu2O (111) (110) facets, metallic copper, or conventional metal-support interfacial sites. Moreover, the stabilization of carboxyl rather than formate-like intermediates follows a similar trend than the methanol production, being preferential on small Cu14O7 and Cu32O16 clusters, underlying a carboxyl-type intermediate path in methanol production.

Large-Scale Coating Methods for Improving Heat Transfer and Stress Management of Metal Hydrides

Wed, 20 May 2026 00:00:00 GMT

Large-Scale Coating Methods for Improving Heat Transfer and Stress Management of Metal Hydrides Warfsmann, Jan; Puszkiel Saldivar, Julian Atilio; Krause, Phillip Sebastian; Wienken, Eike; Klassen, Thomas; Jepsen, Julian Storing hydrogen in interstitial metal hydrides has several advantages. These include high volumetric capacity (50–100 kg/m3), fast kinetics, and safer conditions due to mild operating temperatures (<100 °C) and pressures (<50 bar). However, thermal management and stress development remain challenges to be overcome. There have already been promising methods to improve the performance of metal hydrides, but most are only proof of concept. They have only been investigated on a lab-scale with a few grams of sample. In this work, a commercially available AB2-metal alloy is coated with 10 wt% expanded natural graphite (ENG) and 10 wt% elastomeric binder. The focus is on methods that can easily be scaled up. Two methods (wash-coating and spray-coating) have been successfully applied to prepare hydride-forming materials on a kilogram scale. The performance of the coated material in terms of heat management, stress development, hydrogen capacity, and kinetics is evaluated to be over 50 cycles of hydrogen absorption/desorption. The results are confirmed by a larger-scale set of experiments with ≈0.5 kg of sample. The spray-coating method shows promising results, combining fast preparation, reasonable hydrogen capacity, and the potential to compensate for the bulk of the expansion stress.

Zero-dimensional process simulation model of an anion exchange membrane water electrolyzer system

Fri, 15 May 2026 00:00:00 GMT

Zero-dimensional process simulation model of an anion exchange membrane water electrolyzer system Wienken, Eike S.; Compart, Jonas; Puszkiel Saldivar, Julian Atilio; Klassen, Thomas; Jepsen, Julian Clean hydrogen is vital for achieving net-zero emissions and reducing carbon output in society. Anion exchange membrane water electrolysis is gaining momentum in the growing electrolyzer market as a means of producing climate-neutral hydrogen when paired with renewable energy sources. Anion exchange membrane water electrolyzers do not rely on precious metals for electrocatalysts and do not require harsh caustic conditions, making them a safe, scalable, efficient, and potentially affordable method for splitting water. This investigation uses a zero-dimensional numerical model to assess the operation of a market-ready anion exchange membrane water electrolyzer and its capacity to generate clean hydrogen and recover waste heat. A commercial electrolyzer rack with four nominal 2.4 kWel electrolyzer modules is used to collect experimental data and examine multiple process parameters during dynamic operation from start to steady-state conditions. These include stack temperature, pressure, hydrogen production rate, cell voltage, and current density. The observed average electrolysis efficiencies at the stack and system levels, based on the lower heating value of hydrogen, reach 68.4% and 61.5%, respectively. The recoverability of the generated waste heat at the stack level is approximately 79.4% at 46 °C, providing approximately 340 Wth of heating power and about 111 Wth of exergy heating rate per module. The developed model accurately reproduces the dynamic behavior of electrolyzers, showing strong correlations with experimental data, achieving R2 values of 0.95 or higher across various time-dependent process parameters, and providing new insights into process simulation for system integration, design, and scaling.

Regioirregular and catalytic Mizoroki–Heck reactions

Thu, 01 Apr 2021 00:00:00 GMT

Regioirregular and catalytic Mizoroki–Heck reactions Garnes-Portolés, Francisco; Greco, Rossella; Oliver Meseguer, Judit; Castellanos-Soriano, Jorge; Consuelo Jiménez, M.; López Haro, Miguel; Hernández Garrido, Juan Carlos; Boronat, Mercedes; Pérez-Ruiz, Raúl; Leyva Pérez, Antonio The palladium-catalysed cross-coupling reaction between alkenes and aryl halides (the Mizoroki–Heck reaction) is a powerful methodology to construct new carbon–carbon bonds. However, the success of this reaction is in part hampered by an extremely marked regioselectivity on the double bond, which dictates that electron-poor alkenes react exclusively on the β-carbon. Here, we show that ligand-free, few-atom palladium clusters in solution catalyse the α-selective intramolecular Mizoroki–Heck coupling of iodoaryl cinnamates, and mechanistic studies support the formation of a sterically encumbered cinnamate–palladium cluster intermediate. Following this rationale, the α-selective intermolecular coupling of aryl iodides with styrenes is also achieved with palladium clusters encapsulated within fine-tuned and sterically restricted zeolite cavities to produce 1,1-bisarylethylenes, which are further engaged with aryl halides by a metal-free photoredox-catalysed coupling. These ligand-free methodologies significantly expand the chemical space of the Mizoroki–Heck coupling.