Fabrication of hydrogen-bonded metal-complex frameworks for capturing iodine

Structural Design and Energy and Environmental Applications of Hydrogen-Bonded Organic Frameworks: A Systematic Review

Hydrogen-bonded organic frameworks (HOFs) are emerging porous materials that show high structural flexibility, mild synthetic conditions, good solution processability, easy healing and regeneration, and good recyclability. Although these properties give them many potential multifunctional applications, their frameworks are unstable due to the presence of only weak and reversible hydrogen bonds. In this work, the development history and synthesis methods of HOFs are reviewed, and categorize their structural design concepts and strategies to improve their stability. More importantly, due to the significant potential of the latest HOF-related research for addressing energy and environmental issues, this work discusses the latest advances in the methods of energy storage and conversion, energy substance generation and isolation, environmental detection and isolation, degradation and transformation, and biological applications. Furthermore, a discussion of the coupling orientation of HOF in the cross-cutting fields of energy and environment is presented for the first time. Finally, current challenges, opportunities, and strategies for the development of HOFs to advance their energy and environmental applications are discussed.

Engineering HOF-Based Mixed-Matrix Membranes for Efficient CO2 Separation

Hydrogen-bonded organic frameworks (HOFs) have emerged as a new class of crystalline porous materials, and their application in membrane technology needs to be explored. Herein, for the first time, we demonstrated the utilization of HOF-based mixed-matrix membrane for CO2 separation. HOF-21, a unique metallo-hydrogen-bonded organic framework material, was designed and processed into nanofillers via amine modulator, uniformly dispersing with Pebax polymer. Featured with the mix-bonded framework, HOF-21 possessed moderate pore size of 0.35 nm and displayed excellent stability under humid feed gas. The chemical functions of multiple binding sites and continuous hydrogen-bonded network jointly facilitated the mass transport of CO2. The resulting HOF-21 mixed-matrix membrane exhibited a permeability above 750 Barrer, a selectivity of ~ 40 for CO2/CH4 and ~ 60 for CO2/N2, surpassing the 2008 Robeson upper bound. This work enlarges the family of mixed-matrix membranes and lays the foundation for HOF membrane development.

Cluster-Based Crystalline Materials for Iodine Capture

The treatment of radioactive iodine in nuclear waste has always been a critical issue of social concern. The rational design of targeted and efficient capture materials is of great significance to the sustainable development of the ecological environment. In recent decades, crystalline materials have served as a molecular platform to study the binding process and capture mechanism of iodine molecules, enabling people to understand the interaction between radioactive iodine guests and pores intuitively. Cluster-based crystalline materials, including molecular clusters and cluster-based metal-organic frameworks, are emerging candidates for iodine capture due to their aggregative binding sites, precise structural information, tunable pores/packing patterns, and abundant modifications. Herein, recent progress of different types of cluster materials and cluster-dominated metal-organic porous materials for iodine capture is reviewed. Research prospects, design strategies to improve the affinity for iodine and possible capture mechanisms are discussed.

Facile synthesis and synergistic mechanism of CoFe2O4@three-dimensional graphene aerogels towards peroxymonosulfate activation for highly efficient degradation of recalcitrant organic pollutants

Magnetic CoFe₂O₄ is a promising heterogeneous catalyst with great separation and catalytic performance on peroxymonosulfate (PMS) activation. However, for extremely recalcitrant organic pollutants (e.g. Benzotriazole (BTA)), CoFe₂O₄/PMS system exhibits much low catalytic performance and high metal ion leaching. As such, CoFe₂O₄ supported on three-dimensional graphene aerogels (CoFe₂O₄@3DG) was synthesized via facile hydrothermal method. It turns out that 3DG as supporter significantly enhances specific surface area, redox activity and electron transfer of composite. The degradation rate constant in the CoFe₂O₄@3DG/PMS system (0.0203 min^-1) is 15 times higher than that in the CoFe₂O₄/PMS system (0.0013 min^-1). It results from synergistic activation of PMS by CoFe₂O₄ and 3DG to generate multiple reactive oxygen species (•OH, SO₄^-•, O₂^-• and ¹O₂). Particularly, high graphitization structure and low oxygen groups content of 3DG facilitate PMS adsorption on its surface and electron transfer from BTA to PMS. Ultimately, BTA is degraded into CO_2, NH₃ and intermediates through benzene and triazole ring-opening reactions. Moreover, CoFe₂O₄@3DG/PMS system displays good stability and recyclability. Therefore, this study provides a new way to improve CoFe₂O₄ activity for extremely recalcitrant organic pollutants degradation and new insights into synergistic activation of PMS by CoFe₂O₄ and 3DG, which further advances cobalt-based catalysts in heterogeneous catalysis.