Porous metal–organic frameworks (MOFs) have demonstrated a great potential in proton conduction and luminescence sensing due to functionalized nodes, ligands and channels, or pores. Herein, we prepared a hydrothermally stable Eu-MOF that also resisted acid and base using a bifunctional organic ligand containing carboxylic acid groups, which are easily coordinated to Eu ions, and Eu-phobic tetrazolyl groups as potential proton-hopping sites. The hydrogen bond network, which was constructed by the uncoordinated anionic tetrazolium and the coordinated and free water molecules, endowed this Eu-MOF with the highest proton conductivity of 4.45 × 10–2 S/cm at 373 K and 93% relative humidity. The proton conductivity of the Nafion membrane containing this Eu-MOF increased 1.74 times. More interestingly, the hybrid membrane displayed luminescence pH sensing because the changeable protonation levels of uncoordinated tetrazolium groups along with the pH tuned the emission of embedded Eu-MOFs. Such a dual-functional MOF-based hybrid membrane including proton conduction and pH sensing is reported for the first time, which could open an avenue to the more practical application for functional MOFs.

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Designing high-performance proton-conducting metal−organic frameworks simultaneously having highly hydrothermal stability and a high-density proton carrier remains a great challenge. Fe-MIL-88B is a classic metal− organic framework (MOF) with a large-size one-dimensional (1D) channel lined with a high-density uncoordinated metal atom for postfunctionalization; however this MOF cannot act as a proton conductor due to the weak hydrothermal stability. Here, we prepared an ultrastable isostructure Cr-MIL-88B, which is subsequently functionalized by anchoring 3pyridinesulfonic acid and 2-(4-pyridyl) ethanesulfonic acid on the naked Cr atoms exposed on the surface of the host-framework, producing two new MOFs, i.e. Cr-MIL-88B-pyridine sulfonic acid (abbreviated as Cr-MIL-88B-PSA) and Cr-MIL-88B-pyridine ethanesulfonic acid (abbreviated as Cr-MIL-88B-PESA). Thus, Cr atoms on the host framework were modified by functional sulfonic groups, which stick out toward the center of the channel forming ordered high-density sulfonic groups as proton donors along the open channel and achieving the highest proton conductivity of 4.50 × 10 −2 S cm −1 for Cr-MIL-88B-PESA and 1.58 × 10 −1 S cm −1 for Cr-MIL-88B-PSA, surpassing that of the Nafion membrane.

Porous metal‐organic frameworks (MOFs) loading metal nanoparticles to form a composite photocatalyst demonstrated unique advantages. Modification of the electron donating group on the aromatic linkers of MOFs could increase the absorption range of light, thereby increasing the photocatalytic activity. In this study, we prepared a composite photocatalyst using a stable NH2‐functionalized MOF (UiO‐66‐NH2) to load semiconductor Ag/AgBr nanoparticles, and the resultant composites have intense optical absorption throughout visible light range. The greatly enhanced optical absorption and the unique hetero‐junction between Ag/AgBr and UiO‐66‐NH2 render efficient separation and utilization of photogenerated electron‐hole pairs. Therefore, Ag/AgBr@UiO‐66‐NH2 showed much more excellent photocatalytic activity, compared with unmodified UiO‐66 loading Ag/AgBr (Ag/AgBr@UiO‐66) and reported AgX@MOF catalysts. Moreover, the composite photocatalysts showed excellent stability during cycling experiment.