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Over the last two decades, polymers with superior H₂/CO₂separation properties at 100–300 °C have gathered significant interest for H₂purification and CO₂capture. This timely review presents various strategies adopted to molecularly engineer polymers for this application. We first elucidate the Robeson's upper bound at elevated temperatures for H₂/CO₂separation and the advantages of high‐temperature operation (such as improved solubility selectivity and absence of CO₂plasticization), compared with conventional membrane gas separations at ~35 °C. Second, we describe commercially relevant membranes for the separation and highlight materials with free volumes tuned to discriminate H₂and CO₂, including functional polymers (such as polybenzimidazole) and engineered polymers by cross‐linking, blending, thermal treatment, thermal rearrangement, and carbonization. Third, we succinctly discuss mixed matrix materials containing size‐sieving or H₂‐sorptive nanofillers with attractive H₂/CO₂separation properties.

 

Palladium-based nanostructures have attracted the attention of researchers due to their useful catalytic properties and unique ability to form hydrides, which finds application in hydrogen storage and hydrogen detection. Palladium-based nanowires have some inherent advantages over other Pd nanomaterials, combining high surface-to-volume ratio with good thermal and electron transport properties, and exposing high-index crystal facets that can have enhanced catalytic activity. Over the past two decades, both synthesis methods and applications of 1D palladium nanostructures have advanced greatly. In this review, we start by discussing different types of 1D palladium nanostructures before moving on to the different synthesis approaches that can produce them. Next, we discuss factors including kinetic vs. thermodynamic control of growth, oxidative etching, and surface passivation that affect palladium nanowire synthesis. We also review efforts to gain insight into growth mechanisms using different characterization tools. We discuss the effects of concentration of capping agents, reducing agents, metal halides, pH, and sacrificial oxidation on the growth of Pd-based nanowires in solution, from shape control, to yield, to aspect ratio. Various applications of palladium and palladium alloy nanowires are then discussed, including electrocatalysis, hydrogen storage, and sensing of hydrogen and other chemicals. We conclude with a summary and some perspectives on future research directions for this category of nanomaterials.