NH3 has been used in wide applications, such as fertilizers, hydrogen sources, and working fluids, where proper NH3 adsorbents are required to minimize human health risks in daily NH3 exposure as well as to achieve energy efficiency in energy conversion systems. As NH3 operating pressure differs from each usage, the structure and properties of the NH3 adsorbent need to be optimized in each NH3 operating pressure. Metal–organic frameworks (MOFs) have emerged as promising NH3 adsorbents, which would be customizable for different NH3 pressures due to great structural tunability. We introduce up‐to‐date reports with MOFs as NH3 adsorbents and classify them by the NH3 pressure, from high in adsorption heat pumps to extremely low in daily life sensing. MOFs with high NH3 adsorption capacity and durability are suggested in different NH3 pressure ranges, and their structural factors are discussed to help design high‐performance MOFs for NH3 adsorption in different NH3 pressures.
Gas sponges capable of absorbing, storing, and releasing ions in a reversible manner are in high demand for advanced electronics, energy devices, and sensors. Here, it is shown that brownmillerite BaInO2.5 epitaxial films exhibit the capability to act as solid‐state catalytic hydrogen sponges at a remarkably low temperature (≈100 °C). Compared to sintered pellets with random crystallographic orientations and many defects, BaInO2.5 epitaxial films give three orders of magnitude higher conductivity of hydrogen ions, which can be linked to the presence of well‐ordered 1D channels and lack of grain boundaries and other defects. Using scanning transmission electron microscopy, it is shown that hydrogen ions can be stored near InO4 tetrahedral layers of brownmillerite without destroying the parent framework. The high performance and reproducibility of the BaInO2.5 epitaxial films coupled with ultralow power consumption make them ideal candidates for neuromorphic devices and beyond.
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