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Pt nanoparticles supported on a library of 3d, 4d, 5d and f metal M–N–C catalysts for the ORR. 

Abstract The electrochemical reduction of nitrates (NO₃⁻) enables a pathway for the carbon neutral synthesis of ammonia (NH₃), via the nitrate reduction reaction (NO₃RR), which has been demonstrated at high selectivity. However, to make NH₃synthesis cost‐competitive with current technologies, high NH₃partial current densities (j_NH3) must be achieved to reduce the levelized cost of NH₃. Here, the high NO₃RR activity of Fe‐based materials is leveraged to synthesize a novel active particle‐active support system with Fe₂O₃nanoparticles supported on atomically dispersed Fe–N–C. The optimized 3×Fe₂O₃/Fe–N–C catalyst demonstrates an ultrahigh NO₃RR activity, reaching a maximum j_NH3of 1.95 A cm⁻²at a Faradaic efficiency (FE) for NH₃of 100% and an NH₃yield rate over 9 mmol hr⁻¹cm⁻². Operando XANES and post‐mortem XPS reveal the importance of a pre‐reduction activation step, reducing the surface Fe₂O₃(Fe³⁺) to highly active Fe⁰sites, which are maintained during electrolysis. Durability studies demonstrate the robustness of both the Fe₂O₃particles and Fe–N_xsites at highly cathodic potentials, maintaining a current of −1.3 A cm⁻²over 24 hours. This work exhibits an effective and durable active particle‐active support system enhancing the performance of the NO₃RR, enabling industrially relevant current densities and near 100% selectivity. 

Abstract We summarise the discussions at a virtual Community Workshop on Cold Atoms in Space concerning the status of cold atom technologies, the prospective scientific and societal opportunities offered by their deployment in space, and the developments needed before cold atoms could be operated in space. The cold atom technologies discussed include atomic clocks, quantum gravimeters and accelerometers, and atom interferometers. Prospective applications include metrology, geodesy and measurement of terrestrial mass change due to, e.g., climate change, and fundamental science experiments such as tests of the equivalence principle, searches for dark matter, measurements of gravitational waves and tests of quantum mechanics. We review the current status of cold atom technologies and outline the requirements for their space qualification, including the development paths and the corresponding technical milestones, and identifying possible pathfinder missions to pave the way for missions to exploit the full potential of cold atoms in space. Finally, we present a first draft of a possible road-map for achieving these goals, that we propose for discussion by the interested cold atom, Earth Observation, fundamental physics and other prospective scientific user communities, together with the European Space Agency (ESA) and national space and research funding agencies.