The specific identity of electrolyte cations has many implications in various electrochemical reactions. However, the exact mechanism by which cations affect electrochemical reactions is not agreed upon in the literature. In this report, we investigate the role of cations during the electrochemical reduction of CO2 by chelating the cations with cryptands, to change the interaction of the cations with the components of the electric double layer. As previously reported we do see the apparent suppression of CO2 reduction in the absence of cations. However, using in situ-SEIRAS we see that CO2 reduction does indeed take place albeit at very reduced scales. We also observe that cations play a role in tuning the absorption strengths of not only CO2 as has been speculated, but also that of reaction products such as CO.

The field of electrochemical CO₂ reduction has been transitioning to industrially relevant scales by changing the architecture of the electrochemical cells and moving away from the traditional aqueous H-cells to membrane electrode assemblies (MEA). The reaction environments in MEAs vary drastically from that of aqueous H-cells, which could result in significantly different catalytic activity. In this paper, we test AgPd alloys, one of the most promising CO producing catalysts reported, at industrially relevant scales (50 to 200 mA/cm²) in a MEA configuration. We report that, with increasing Pd composition in the electrode, the CO selectivity reduces from 99 % for pure Ag to 73 % for pure Pd at 50 mA/cm². The MEA configuration helps attain a high CO partial current density of 123 mA/cm². We find that catalytic activity reported in aqueous H-Cells does not translate at higher current densities and that cell architecture must play an important role in benchmarking catalytic activity.

Although of pivotal importance in heterogeneous hydrogenation reactions, the amount of hydrogen on catalysts during reactions is seldom known. We demonstrate the use of neutron imaging to follow and quantify hydrogen containing species in Cu/ZnO catalysts operando during methanol synthesis. The steady-state measurements reveal that the amount of hydrogen containing intermediates is related to the reaction yields of CO and methanol, as expected from simple considerations of the likely reaction mechanism. The time-resolved measurements indicate that these intermediates, despite indispensable within the course of the reaction, slow down the overall reaction steps. Hydrogen-deuterium exchange experiments indicate that hydrogen reduction of Cu/ZnO nano-composites modifies the catalyst in such a way that at operating temperatures, hydrogen is dynamically absorbed in the ZnO-nanoparticles. This explains the extraordinary good catalysis of copper if supported on ZnO by its ability to act as a hydrogen reservoir supplying hydrogen to the surface covered by CO2, intermediates, and products during catalysis.

Using renewable energy as an input, Power-to-X technologies have the potential to replace fossil fuels and chemicals with dense-energy carriers that are instead derived out of thin air. In this work, we put into context what the industrial-scale production of chemicals from ambient CO₂ using CO₂ electrolysis means in terms of future required operating conditions and the device and catalyst scales that will be needed for the technology to assume its role in our global energy system.

Solar-powered electrochemical production of hydrogen through water electrolysis is an active and important research endeavor. However, technologies and roadmaps for implementation of this process do not exist. In this perspective paper, we describe potential pathways for solar-hydrogen technologies into the marketplace in the form of photoelectrochemical or photovoltaic-driven electrolysis devices and systems. We detail technical approaches for device and system architectures, economic drivers, societal perceptions, political impacts, technological challenges, and research opportunities. Implementation scenarios are broken down into short-term and long-term markets, and a specific technology roadmap is defined. In the short term, the only plausible economical option will be photovoltaic-driven electrolysis systems for niche applications. In the long term, electrochemical solar-hydrogen technologies could be deployed more broadly in energy markets but will require advances in the technology, significant cost reductions, and/or policy changes. Ultimately, a transition to a society that significantly relies on solar-hydrogen technologies will benefit from continued creativity and influence from the scientific community.

We have investigated the potential of metal-organic frameworks for immobilising single atoms of transition metals using a model system of Pd supported on NH₂-MIL-101(Cr). Our transmission electron microscopy and in situ Raman spectroscopy results give evidence for the first time that functionalised metal-organic frameworks may support, isolate and stabilise single atoms of palladium. Using thermal desorption spectroscopy we were able to evaluate the proportion of single Pd atoms. Furthermore, in a combined theoretical-experimental approach, we show that the H-H bonds in a H₂ molecule elongate by over 15% through the formation of a complex with single atoms of Pd. Such deformation would affect any hydrogenation reaction and thus the single atoms supported on metal-organic frameworks may become promising single atom catalysts in future.

The presence of water (H₂O) is essential for the adsorption of carbon dioxide (CO₂) on the serpentine particles. However, the use of H₂O in the slurry bed columns requires high energy inputs to maintain the temperature during operation above ambient temperatures. Moreover, the separation, drying, handling, and processing of the product stream will pose challenges and cost even more energy. Here, we show the proof of principle of CO₂ sequestration on mineral particles in a fluidized bed using a moist CO₂ stream. The setup allows wetting of the particles while maintaining fluidization. The results show 50% mineral conversion and 40% CO₂ conversion in 8 min at 1 bar and 90 °C.