Aromatic-aliphatic hydrocarbon separation with oriented monolayer polyhedral membrane

Redox-mediated oxygen evolution reaction: Engineering oxygen vacancies and heterojunctions in CeFeCo-UiO-66/layered double hydroxide via a two-step corrosion strategy

Modifying metal-organic frameworks (MOFs)-based electrocatalysts remains crucial for enhancing oxygen evolution reaction (OER) performance. Although oxygen vacancies (VO) are recognized as important for OER, their concentration control and relationship with catalytic activity remain unclear. In this study, we employ the redox potential difference between Co2+/3+ (0.55 eV) and Ce3+/4+ (1.44 eV) to induce corrosion on iron foam (IF), driving the redox reaction Ce4+ + Co2+ → Ce3+ + Co3+ to generate VO. The VO content can be qualitatively controlled by adjusting corrosion time, as verified by electron paramagnetic resonance (EPR). The CeFeCo-UiO-66/LDH catalyst delivers exceptional catalytic activity (overpotential η = 273 ± 3 mV @ 100 mA cm-2). Combined X-ray photoelectron spectroscopy (XPS), EPR, in-situ Raman, and Density functional theory (DFT) analyses reveal that the redox interaction between Ce and Co generates VO. These VO species facilitate the formation of active CoOOH during the OER. This work offers insights for designing VO engineering strategies in electrocatalytic systems.

Suppressing Dendrite Growth by Dolosse-Structured ZIF-67 Polycrystalline Membranes Through Eliminating Interfacial Electrolyte Turbulence on Zinc Anode

Aqueous Zn-ion batteries (ZIBs) are considered a promising candidate for next-generation energy storage devices, but the Zn dendrite problem limits their practical application potential. Although existing solutions, such as electrolyte additives and electrode coatings, can effectively address this issue, but almost all these solutions are based on a static electrolyte model and overlook the relationship between electrolyte flow and dendrite growth. Herein, inspired by the principle of dolosse to reduce the impact of waves on coastlines, we utilized the epitaxial growth characteristics of metal-organic frameworks (MOFs) to construct a ZIF-67 polycrystalline membrane with macro-microporous on Zn foil (D-67M@Zn). The dolosse-like structure of the membrane effectively eliminates turbulence at the electrode-electrolyte interface, enabling Zn2+ to deposit in a stable electrolyte environment, reducing the secondary nucleation rate of Zn, and inhibiting dendrite growth. The macro-microporous skeleton also helps regulate the morphology of Zn deposition, as confirmed by fluid dynamics analysis and AC-STEM. Benefiting from the unique properties of D-67M, both symmetric cells and full cells based on the D-67M@Zn anode exhibit impressive cycling stability.

Rational Design of Superhydrophobic and Flexible Oriented MOF Nanosheet Membrane for Highly Efficient Ethanol-Water Separation

Highly efficient and energy-conserving membrane separation technology holds vast potential for applications in the bioethanol production process. This work reports a strategy for the fast preparation of an oriented and flexible two-dimensional metal-organic framework (MOF) nanosheet membrane by an electrochemical deposition method. The oriented MOF nanosheet membrane growth, followed by spin-coating of polydimethylsiloxane, resulted in an efficiently formed superhydrophobic and ethanol affinity membrane for separating ethanol from aqueous solution. Vertically aligned MOF nanosheets with strong ethanol affinity and superhydrophobic membrane surfaces simultaneously promote the transport process, thus delivering a relatively high flux of 1.63 kg·m-2·h-1 and good separation factor of 14.89 in the pervaporation of 5 wt % ethanol aqueous solution. The oriented arrangement of MOF nanosheets combined with polydimethylsiloxane can significantly enhance the pervaporation selectivity and flux, creating a preferential pathway for the production of biofuel.

Tailored Polymer-Zeolite Imidazolate Framework Membranes for Aperture-Matched C4 Hydrocarbon Separation

The integration of metal-organic frameworks (MOFs) with polymers for efficient C4 hydrocarbon separation membranes remains challenging, primarily due to inherent phase incompatibility. This work presents an in-situ synthesis strategy for polymer-zeolitic-imidazolate frameworks (polyZIF), utilizing polymer-metal-ligand coordination bonds combined with structural directing agents to produce crystalline microporous frameworks. With an accessible BET surface area of 261 m2 g-1 and a permanent porosity of ca. 4.42 Å, polyZIF membrane demonstrates butadiene permeance (∼332 GPU) and the selectivity over n-butene, n-butane, iso-butene, and iso-butane (17.2, 28.1, 21.5, and 34.8) under mixed gas conditions, respectively. Demonstrating practical scalability, the improved dispersibility and reduced interfacial defects in polyZIF facilitates fabrication of large-area defect-free membranes (up to 80 cm2) while maintaining robust C4 separation performance. This advancement not only establishes a novel preparation for constructing polyZIF membranes with C4 hydrocarbon molecular-sieving capability but also provides critical insights into industrial application of ZIF-based polymer membranes.

Thermodynamically-Driven Phase Engineering and Reconstruction Deduction of Medium-Entropy Prussian Blue Analogue Nanocrystals

Prussian blue analogs (PBAs) are exemplary precursors for the synthesis of a diverse array of derivatives.Yet, the intricate mechanisms underlying phase transitions in these multifaceted frameworks remain a formidable challenge. In this study, a machine learning-guided analysis of phase transitions in a medium-entropy PBA system is delineated, utilizing an array of descriptors that encompass crystallographic phases, structural subtleties, and fluctuations in multimetal valence states. By integrating multimodal simulations with experimental validation, a thermodynamics-driven phase transformation model for medium-entropy PBA is established and accurately predicted the critical synthesis parameters. A constellation of advanced techniques-including atomic force microscopy coupled with Kelvin probe force microscopy for individual nanoparticles, X-ray absorption spectroscopy, operando ultraviolet-visible spectroscopy, in situ X-ray diffraction, theoretical calculations, and multiphysics simulations-substantiated that the iron oxide@NiCoZnFe-PBA exhibits both exceptional stability and remarkable electrochemical activity. This investigation provides profound insights into the phase transition dynamics of polymetallic complexes and propels the rational design of other thermally-induced derivatives.