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In this study, two functionalized metal-organic frameworks (MOFs), UiO-66-SOH and UiO-66-NH, were synthesized. Then, different composite proton exchange membranes (PEMs) were prepared by single doping and codoping of these two MOFs, respectively. It was found that codoping of these two MOFs with suitable sizes was more conducive to the proton conductivity enhancement of the composite PEM. A synergistic effect between these two MOFs led to the the formation of more consecutive hydration channels in the composite PEM. It further greatly promoted the proton conductivity of the composite PEM. The proton conductivity of the codoped PEM reached up to 0.256 S/cm under 90 °C, 95% RH, which was ∼1.17 times higher than that of the recast Nafion (0.118 S/cm). Besides, the methanol permeability of the codoped PEM was prominently decreased owing to the methanol trapping effect of the pores of these two MOFs. Meanwhile, the high water and thermal stabilities of these two MOFs were beneficial to the high proton conductivity stability of the codoped PEM under high humidity and high temperature. The proton conductivity of the codoped PEM was almost unchanged throughout 3000 min of testing under 90 °C, 95% RH. This work provides a valuable reference for designing different functionalized MOFs to synergistically promote the proton conductivities of PEMs.

A new metal-organic framework/graphene oxide composite (IRMOF-3/GO) with high adsorption capacity of copper(II) (maximal adsorption amount = 254.14 mg/g at pH 5.0 and 25 °C) was prepared. Novel and highly efficient nanofiltration (NF) membrane can be facilely fabricated via surface decoration of IRMOF-3/GO onto polydopamine (PDA)-coated polysulfone (PSF) substrate. After decoration of IRMOF-3/GO, membrane surface potential increased from 6.7 to 13.1 mV at pH 5.0 and 25 °C. Due to the adsorption effect of IRMOF-3/GO and the enhancement of membrane surface potential, the prepared NF membrane (the loading amount of IRMOF-3/GO is ca. 13.6 g/m) exhibits a highly efficient rejection of copper(II). The copper(II) rejection reaches up to ∼90%, while maintaining a relatively high flux of ∼31 L/m/h at the pressure of 0.7 MPa and pH 5.0. Moreover, the membrane also presents an outstanding stability throughout the 2000 min NF testing period. Thus, the newly developed NF membrane shows a promising potential for water cleaning. This work provides a worthy reference for designing highly efficient NF membranes modified by metal-organic framework (MOF) relevant materials.

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Sweat sensors play a significant role in personalized healthcare by dynamically monitoring biochemical markers to detect individual physiological status. The specific response to the target biomolecules usually depends on natural oxidase, but it is susceptible to external interference. In this work, we report tryptophan- and histidine-treated copper metal-organic frameworks (Cu-MOFs). This amino-functionalized copper-organic framework shows highly selective activity for ascorbate oxidation and can serve as an efficient ascorbate oxidase-mimicking material in sensitive sweat sensors. Experiments and calculation results elucidate that the introduced tryptophan/histidine fundamentally regulates the adsorption behaviors of biomolecules, enabling ascorbate to be selectively captured from complex sweat and further efficiently electrooxidized. This work provides not only a paradigm for specifically sweat sensing but also a significant understanding of natural oxidase-inspired MOF nanoenzymes for sensing technologies and beyond.

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A B S T R A C TThe adsorpion of methylene blue (MB) from aqueous solution on a highly porous metal-organic framework material [Cu 3 (BTC) 2 (H 2 O) 3 ] was studied in conjunction with the adsorption isotherm, kinetics and regenerate of the sorbent. The adsorption isotherms of MB on [Cu 3 (BTC) 2 (H 2 O) 3 ] followed both the Freundlich isotherm and the Langmuir adsorption isotherm. Adsorption kinetics was determined from the experimental data, and the results showed that the adsorption obeyed a pseudo-second-order kinetics. The best oscillate time and the best [Cu 3 (BTC) 2 (H 2 O) 3 ] amount were discussed, and [Cu 3 (BTC) 2 (H 2 O) 3 ] gave high adsorption in only 5 min. The used [Cu 3 (BTC) 2 (H 2 O) 3 ] could be regenerated by glycol solution, thus recycled. SEM image and FT-TR spectra of recycled [Cu 3 (BTC) 2 (H 2 O) 3 ] after different adsorption times were compared. The high adsorption capacity and excellent reusability make [Cu 3 (BTC) 2 (H 2 O) 3 ] attractive for the removal of MB from aqueous solution.

Excellent proton‐conductive accelerators are indispensable for efficient proton‐exchange membranes (PEMs). Covalent porous materials (CPMs), with adjustable functionalities and well‐ordered porosities, show much promise as effective proton‐conductive accelerators. In this study, an interconnected and zwitterion‐functionalized CPM structure based on carbon nanotubes and a Schiff‐base network (CNT@ZSNW‐1) is constructed as a highly efficient proton‐conducting accelerator by in situ growth of SNW‐1 onto carbon nanotubes (CNTs) and subsequent zwitterion functionalization. A composite PEM with enhanced proton conduction is acquired by integrating CNT@ZSNW‐1 with Nafion. Zwitterion functionalization offers additional proton‐conducting sites and promotes the water retention capacity. Moreover, the interconnected structure of CNT@ZSNW‐1 induces a more consecutive arrangement of ionic clusters, which significantly relieves the proton transfer barrier of the composite PEM and increases its proton conductivity to 0.287 S cm−1 under 95 % RH at 90 °C (about 2.2 times that of the recast Nafion, 0.131 S cm−1). Furthermore, the composite PEM displays a peak power density of 39.6 mW cm−2 in a direct methanol fuel cell, which is significantly higher than that of the recast Nafion (19.9 mW cm−2). This study affords a potential reference for devising and preparing functionalized CPMs with optimized structures to expedite proton transfer in PEMs.