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The abstract is available here: https://uscholar.univie.ac.at/o:1652323

Paweł Łukasz Zajdel, David G. Madden, Robin Babu, Marco Tortora, Diego Mirani, Nikolay Nikolaevich Tsyrin, Luis Bartolomé, Eder Amayuelas, David Fairen-Jimenez, Alexander Rowland Lowe, Mirosław Adam Chorążewski, Juscelino B. Leao, Craig M. Brown, Markus Bleuel, Victor Stoudenets, Carlo Massimo Casciola, María Echeverría, Francisco Bonilla, Giulia Grancini, Simone Meloni, Yaroslav Grosu, Controlling the pressure at which liquids intrude (wet) and extrude (dry) a nanopore is of paramount importance for a broad range of applications, such as energy conversion, catalysis, chromatography, separation, ionic channels, and many more. To tune these characteristics, one typically acts on the chemical nature of the system or pore size. In this work, we propose an alternative route for controlling both intrusion and extrusion pressures via proper arrangement of the grains of the nanoporous material. To prove the concept, dynamic intrusion–extrusion cycles for powdered and monolithic ZIF-8 metal–organic framework were conducted by means of water porosimetry and in operando neutron scattering. We report a drastic increase in intrusion–extrusion dynamic hysteresis when going from a fine powder to a dense monolith configuration, transforming an intermediate performance of the ZIF-8 + water system (poor molecular spring) into a desirable shock-absorber with more than 1 order of magnitude enhancement of dissipated energy per cycle. The obtained results are supported by MD simulations and pave the way for an alternative methodology of tuning intrusion–extrusion pressure using a macroscopic arrangement of nanoporous material.

5 figures.-- Supporting information available.-- This ACS article is provided under the terms of this ACS AuthorChoice/Editors’ Choice via Creative Commons CC-BY agreement: https://pubs.acs.org/page/policy/authorchoice_ccby_termsofuse.html, Developing highly efficient and stable photoelectrochemical (PEC) water-splitting electrodes via inexpensive, liquid phase processing is one of the key challenges for the conversion of solar energy into hydrogen for sustainable energy production. ZnO represents one the most suitable semiconductor metal oxide alternatives because of its high electron mobility, abundance, and low cost, although its performance is limited by its lack of absorption in the visible spectrum and reduced charge separation and charge transfer efficiency. Here, we present a solution-processed water-splitting photoanode based on Co-doped ZnO nanorods (NRs) coated with a transparent functionalizing metal–organic framework (MOF). The light absorption of the ZnO NRs is engineered toward the visible region by Co-doping, while the MOF significantly improves the stability and charge separation and transfer properties of the NRs. This synergetic combination of doping and nanoscale surface functionalization boosts the current density and functional lifetime of the photoanodes while achieving an unprecedented incident photon to current efficiency (IPCE) of 75% at 350 nm, which is over 2 times that of pristine ZnO. A theoretical model and band structure for the core–shell nanostructure is provided, highlighting how this nanomaterial combination provides an attractive pathway for the design of robust and highly efficient semiconductor-based photoanodes that can be translated to other semiconducting oxide systems., A.G.-G., A.K.S., F.M., A.G., D.A.Z., and D.A. acknowledge funding received from the European Union’s Horizon 2020 research and innovation programme under the Marie Skłodowska-Curie Grant Agreement No 722176. W.K.M., A.M.B., and J.H.F. acknowledge financial support from Spanish Ministry MINEICO under Project ENE2016-79282-C5-1-R (AEI/UE/FEDER) and the Gobierno de Aragón (Grupo Reconocido DGA T03_17R, FEDER/UE y DGA T03_20R).

A novel, mixed-linker metal−organic framework (MOF) was synthesized, and the resulting macromolecular assembly had enhanced activity and stability in comparison to the isostructural CuBTC (aka HKUST-1). Mixtures of 5-aminoisophthalic acid (AIA) and 1,3,5-benzenetricarboxylic acid (BTC) were combined at different ratios to incorporate aryl amine groups into the MOF that were readily amenable to postsynthetic modification. As one example, the amine groups were reacted with decanoyl chloride (DC) through the formation of amide linkages, which overcame a major shortcoming of CuBTC by stabilizing the MOF toward ammonia vapor during breakthrough experiments and to liquid water for over 24 h. Furthermore, the MOF modified with DC exhibited ∼70% increases in CO₂/N₂ and CO₂/H₂O selectivity at flue gas relevant conditions relative to CuBTC. The modified MOFs had increased compatibility with polyacrylonitrile, poly(styrene-block-isoprene-block-styrene), and poly(styrene-block-ethylene-ranbutylene-block-styrene) polymers, which made them ideal for incorporation in polymer fibers and composite films and reduced defects generally associated with polymer−nanoparticle systems. Finally, the AIA and DC-modified MOFs had significantly enhanced moisture stability relative to unmodified CuBTC. Overall, this facile modification route provides the framework for higher-performance materials in applications such as filtration, gas storage, and flue gas scrubbing, among many others.

We report the use of two earth abundant molybdenum sulfide-based cocatalysts, Mo3S132- clusters and 1T-MoS2 nanoparticles (NPs), in combination with the visible-light active metal-organic framework (MOF) MIL-125-NH2 for the photocatalytic generation of hydrogen (H2) from water splitting. Upon irradiation (λ ≥ 420 nm), the best-performing mixtures of Mo3S132-/MIL-125-NH2 and 1T-MoS2/MIL-125-NH2 exhibit high catalytic activity, producing H2 with evolution rates of 2094 and 1454 μmol h-1 gMOF-1 and apparent quantum yields of 11.0 and 5.8% at 450 nm, respectively, which are among the highest values reported to date for visible-light-driven photocatalysis with MOFs. The high performance of Mo3S132- can be attributed to the good contact between these clusters and the MOF and the large number of catalytically active sites, while the high activity of 1T-MoS2 NPs is due to their high electrical conductivity leading to fast electron transfer processes. Recycling experiments revealed that although the Mo3S132-/MIL-125-NH2 slowly loses its activity, the 1T-MoS2/MIL-125-NH2 retains its activity for at least 72 h. This work indicates that earth-abundant compounds can be stable and highly catalytically active for photocatalytic water splitting, and should be considered as promising cocatalysts with new MOFs besides the traditional noble metal NPs.

This research was supported through the Center for Gas Separations Relevant to Clean Energy Technologies, an Energy Frontier Research Center funded by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under award DE-SC0001015. We thank Arkema and Gerald K. Branch for fellowship support of E.D.B. and Ateneo Project 2011 ORTO11RRT5 for financial support of S.B., C.L., and S.C. C.L. acknowledges the Mega-grant of the Russian Federation Government number 14.Y26.31.0001 for support. An iron(II)-based metal–organic framework featuring coordinatively unsaturated redox-active metal cation sites, Fe2(dobdc) (dobdc4– = 2,5-dioxido-1,4-benzenedicarboxylate), is shown to strongly bind nitric oxide at 298 K. Adsorption isotherms indicate an adsorption capacity greater than 16 wt %, corresponding to the adsorption of one NO molecule per iron center. Infrared, UV–vis, and Mössbauer spectroscopies, together with magnetic susceptibility data, confirm the strong binding is a result of electron transfer from the FeII sites to form FeIII–NO– adducts. Consistent with these results, powder neutron diffraction experiments indicate that NO is bound to the iron centers of the framework with an Fe–NO separation of 1.77(1) Å and an Fe–N–O angle of 150.9(5)°. The nitric oxide-containing material, Fe2(NO)2(dobdc), steadily releases bound NO under humid conditions over the course of more than 10 days, suggesting it, and potential future iron(II)-based metal–organic frameworks, are good candidates for certain biomedical applications. Postprint