A new method was developed for post-modification of porous aromatic framework-1 (PAF-1) with chloride and then amine groups confirmed by different characterizations such as nuclear magnetic resonance (NMR), X-ray photoelectron spectroscopy (XPS), and Fourier transform infrared spectroscopy (FTIR). Compared to PAF-1, the amine-functionalized PAF-1 (PAF-1-NH₂) exhibits a 50% improvement in carbon dioxide (CO₂) adsorption capacity reaching 42 cm³·g^-1 at room temperature and 1 bar, and the uptakes under CO₂ concentration in air (4 kPa) and flue gas (150 kPa) also greatly increase. The column breakthrough experiments showed that PAF-1-NH₂ can separate CO₂ from a simulated flue gas of CO₂/N₂ (15:85, v/v) indicating its potential applications in post-combustion systems.

Water pollution has become a global environmental problem, such as that caused by Pb(II). Therefore, there is an urgent need to develop multifunctional materials for Pb(II) monitoring and removal. Yet, developing bifunctional materials for sensitive detection and efficient removal of Pb(II) remain challenging. Here, a metal-organic gel (HNU-G4) was constructed for sensible responsive detection and efficient adsorption of Pb(II). The dry gel was obtained through the freeze-dried process and can be used for the Pb(II) detection via fluorescence quenching; the lowest limit of detection for Pb(II) is 0.766 ppb. Furthermore, HNU-G4 has an effective maximum adsorption capacity of 480.00 mg·g^-1 for Pb(II) in water. Additionally, the gel demonstrates excellent recoverability and interference resistance, which can be used in the detection and recovery of actual reclaimed water samples to prevent secondary contamination. This study developed a bifunctional gel material for sensitive detection and effective removal of Pb(II) from water, providing a suggested strategy to tackle the heavy metal contamination problem.

Chiral indene skeletons are widely found in biologically active natural products and pharmaceutical molecules, making indene synthesis an ongoing research hotspot in organic synthetic chemistry. However, the construction of chiral spiro-indenes bearing all-carbon quaternary stereocenters via catalytic asymmetric synthesis remains challenging due to their inherent rigidity and hindrance. Herein, we present a solution to this unmet challenge through palladium-catalyzed asymmetric (4 + 2) dipolar cyclization by trapping π-allyl-Pd 1,4-dipoles with indene-involved ketenes generated in situ from 1-diazonaphthalene-2(1H)-ones via visible light-induced Wolff rearrangement. This protocol features mild reaction conditions, wide substrate scope, and high enantio- and diastereoselectivities [31 examples, up to 86% yield, 97% enantiomer excess (ee) and 19:1 diastereoisomer ratio (dr)].

The traditional industry synthesizes urea through the reaction of NH₃ and CO₂ under high temperatures and pressure. Electrochemical catalysis, which could replace the traditional ammonia synthesis route, i.e., co-reduces carbon dioxide with nitrogen sources [nitrite (NO₂^-), nitrate (NO₃^-), nitrogen (N₂), and nitric oxide (NO)] to synthesize urea, is a promising strategy for the synthesize of urea under environmental conditions. Unlike traditional industry routes, electrochemical catalysis urea synthesis is beneficial for both resource utilization and environmental protection. Herein, the recent research progress of electrocatalytic urea synthesis is summarized, with emphasis on the design and preparation of the catalyst for the coupling of CO₂ and nitrogen species directly to urea. The involved reaction mechanism of C-N coupling is generalized and discussed. Furthermore, the difficulties and challenges at the present stage are summarized, and the development direction of electrocatalytic synthesis of urea is prospected.

Hydrogen obtained from decomposition of natural gas with direct sequestration of carbon in solid form could be an attractive and cost-effective alternative for large-scale hydrogen production. We report here the use of a carbon-based catalyst to achieve the catalytic decomposition of methane (CMD) at medium temperature, 800 °C, under induction heating (IH). Analyses of the catalytic results and characterizations of the spent catalyst have shown that the carbon deposited during the reaction acts as the active phase for the reaction and can, therefore, be recycled infinitely. This autocatalytic effect can only be observed when the carbon catalyst operates under IH because the same catalyst operating under Joule heating (JH) deactivates rapidly in the same way as that already reported in the literature and no autocatalytic effect has been observed. The carbon formed is in the form of a graphene layer with a high degree of graphitization and is completely different from the carbon black powder obtained in other processes. These promising results could lay the groundwork for the development of an industrially and economically viable way to convert natural gas into turquoise hydrogen, using renewable energy and low-cost catalysts, with better resistance to poisoning by impurities present in the processing load. The combination of a carbon-based catalyst and non-contact IH could also lead to combined catalytic processes for many challenging reactions.

Owing to its unique structure, porosity and photoresponse properties, two-dimensional hierarchically porous (2D-HP) C₃N₄ has attracted wide attention in environmental remediation and sustainable energy evolution fields. Up to today, 2D-HP C₃N₄ has been developed as an efficient photocatalyst for various environmental/energy photocatalytic applications. Its advantages in promoting light harvesting, reactant diffusion and transportation, surface molecule activation and photoinduced carrier separation have been verified. In this perspective, we highlighted the advantages of 2D-HP C₃N₄ in various photocatalytic reactions such as water splitting and H₂O₂ production. The relevant mechanism was simultaneously discussed. Moreover, the prospects and obstacles for the industrial utilization of 2D-HP C₃N₄-based photocatalysts are outlined and summarized. Finally, we envision available approaches for the deployment of 2D-HP C₃N₄-based materials to promote its practical application.

With the depletion of traditional energy sources and growing environmental concerns, it is becoming increasingly urgent to develop green, low-emission renewable energy technologies to replace fossil fuel-driven methods that emit carbon dioxide (CO₂). Currently, the electrochemical production of high-value-added chemicals and fuels from CO₂ has aroused great interest from scientists. However, to make full use of CO₂ for the preparation of chemicals, it is necessary to expand the range of electrosynthesis methods, in particular by expanding reaction pathways through the reaction of CO₂ with different substrates. In general, CO₂ can form new covalent bonds with substrate molecules through the formation of C−X bonds, including C−H, C−C, C−N, C−O, and C−S bonds, which would expand the range of possible products by diversifying the reaction pathway. In this review, we focus on the research progress in electrochemical conversion of CO₂ through C−X bond formation. We start by examining fundamentals of the reactions and summarizing the reaction modes. Next, we discuss the electrosynthesis of C−X bonds (C−H, C−C, C−N, C−O, C−S) using CO₂ and different substrate molecules. Finally, (i) strategies for the design and activity optimization of catalyst materials and (ii) the future development of forming five types of bonds from CO₂ and small molecules are discussed, along with an outlook on their future research prospects.

Microporous solids are famous for their high surface area and pore size at the molecular scale, which are crucial for the applications of adsorption, separation and catalysis. An ideal porous solid would simultaneously have a high surface area and nanopores with the desired opening size. However, due to the uncontrollable reaction process of porous organic frameworks (POFs), the acquisition of such a solid is still technically limited. Herein, we reported a simple but platform-wide pore partition strategy to improve the porosity of porous aromatic frameworks (PAFs) in two aspects. This strategy was achieved by introducing a partition unit with flexible linkage to segment the original voids of PAFs into multiple micropore domains. The obtained partitioning PAFs have 130%-217% increments in surface area due to the creation of extra accessible surfaces while the pores are segmented into smaller ones. Notably, the partitioning PAFs showed significantly increased adsorption capacity for CO₂ due to their improved surface area. At the same time, the narrowed pore size allowed selective capture of dye molecules by their size differences. Similar to their parent PAFs, the partitioning PAFs retained their high stability in harsh environments. A simple and universal pore partition strategy will be an important step in improving PAF porosity to desired functions.

Selective hydrogenation of phenylacetylene to styrene plays a vital role in fine chemical synthesis with palladium (Pd)-based catalysts as the active components and usually suffered from low selectivity due to over-hydrogenation and low stability through polymerization (c.a. green oil generation). In this work, we found that by confining the Pd atom within a Pd-Ln (Ln: rare earth elements, such as Y, Lu, etc.) diatomic structure [diatomic catalyst (DAC)], the reaction performance of selective hydrogenation of phenylacetylene has been greatly promoted, in which 92% styrene selectivity has been determined at 100% phenylacetylene conversion. This would be attributed to the diatomic structure established, which was achieved by introducing Pd-Ln precursors and confirmed by high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM) and X-ray adsorption fine structure (XAFS) characterizations and it was demonstrated that slight electron transfer from Ln to the adjacent isolated Pd makes it slightly negatively charged and facilitated the styrene formation. Besides, a Langmuir-Hinshelwood model was established to describe the whole reaction mechanism. After a systematic kinetic investigation, it suggests that the C₈H₆^* + H^* elementary step is probably the kinetically relevant for the whole reaction and the surface of the catalyst is mainly covered by C₈H₆^*. The energy relationship of each step along phenylacetylene hydrogenation was quantitatively described by means of parity fitting and gas isothermal adsorption, providing insights into the selective hydrogenation of phenylacetylene over 0.02%Pd-Ln/C (Ln = Y/Lu) catalysts and pave the way of catalytic design at the atomic level.

Niacin is well known not only as vitamin B3 but also as an important chemical, and has wide applications in the fields of food, farming, medicine, pharmaceuticals, and industry. With the rapid development of human society, the requirement for niacin has been increasing constantly worldwide. Meanwhile, development of green routes to produce niacin under mild conditions has become particularly urgent to substitute the conventional reaction process with the consideration of energy conservation and emission reduction. Among various synthesis routes of niacin, selective oxidation of 3-methyl-pyridine and hydrogen peroxide (H₂O₂) in the liquid phase has become the focus of research due to its distinct advantages, such as mild reaction conditions, environmentally friendly reaction processes, and so on. Herein, zeolite-based catalysts have been first applied in the liquid phase synthesis of niacin from 3-methyl-pyridine and 30%H₂O₂ under mild reaction conditions. In addition, Cu-based 13X zeolite is found to show the highest catalytic performance, and optimal catalytic reaction systems have been established. This work provides a green and optional route for the synthesis of niacin.

Oxygen evolution reactions (OER), commonly employed in applications such as metal-air batteries, water electrolysis, fuel cells, etc., often suffer from slow kinetics, thus leading to ultra-high potentials that severely affect device energy efficiency. Metal-organic frameworks (MOFs) have garnered massive attention as electrodes for OER, benefiting from their highly ordered porous frameworks, abundant accessible active metal sites, and adjustable lattice structures. However, using powdered MOFs in OER poses a challenge, limiting the exposure of numerous active sites and resulting in suboptimal efficiency. To address this limitation, the trend towards designing MOF-based self-supported electrodes with enhanced contact between MOFs and the current collector has gained considerable attention for OER applications. This review highlights recent advancements and future prospects in developing MOF-based self-supported electrodes for OER. We delve into various aspects, including preparation methods, optimization strategies, catalytic efficiencies, and OER mechanisms with MOF-based electrocatalysts. Furthermore, we explore the existing challenges associated with MOF-based self-supported electrodes for OER. This comprehensive overview provides valuable insights into the evolving landscape of MOF-based materials in advancing OER.

Herein, SrSnO₃ perovskite and Nd₂Sn₂O₇ pyrochlore with definite structures have been synthesized using a hydrothermal method, and the differences in their reactive sites for the oxidative coupling of methane (OCM) are investigated. The primary products of perovskite and pyrochlore are C₂ hydrocarbons and CO_x, respectively. The C₂ selectivity of perovskite is primarily affected by basic sites and chemisorbed oxygen species O₂^2-. For pyrochlore, the key factors affecting methane conversion and CO_x selectivity are the acidic sites and reactive oxygen species (chemisorbed oxygen species and weakly bonded lattice oxygen). The chemisorbed oxygen species of pyrochlore are directly generated through intrinsic oxygen vacancies, whereas those of perovskite are generated through oxygen vacancies created under high-temperature lattice distortions. The tightness of the stacking between [SnO₆] octahedra is the main factor affecting the acidic sites and oxygen vacancies of the two composite oxides. The stacking of [SnO₆] octahedra in pyrochlore is loose, resulting in a relatively weak Sn–O bond strength. During the OCM reaction, the Sn–O bond is prone to breakage, resulting in abundant acidic sites and oxygen vacancies. Additionally, the influence of basic sites on the amount of chemisorbed oxygen species is more important than that of oxygen vacancies, which is attributed to the fact that basic sites can stabilize chemisorbed oxygen species on the catalyst surface.

Circularly polarized luminescence (CPL) has emerged as a focal point in luminescent materials research, reflecting a growing field of study. Responding to the demand for practical applications across diverse sectors, there is a critical need for CPL materials with high luminescence dissymmetry factors (g_lum) and adjustable optical performance, driving the development of novel materials and methodological approaches. Chiral nematic liquid crystals (N^*-LCs) have attracted significant attention as promising candidates for producing high-performance CPL materials due to their ability to exhibit enhanced g_lum and modulate circularly polarized light. This review comprehensively presents the stimuli-responsive CPL properties, utilizing N^*-LCs as chiral templates doped with various photochromic compounds, particularly azobenzene, spiropyran (SP), diarylethene and overcrowded alkene. By elucidating the dynamic interplay between molecular structure, supramolecular organization, and optical response, it offers a profound understanding of the stimuli-responsive CPL behaviors. Additionally, the review also explores the multifaceted applications of photochromic N^*-LCs materials, spanning advanced display technologies, optical data storage, and beyond. By examining diverse avenues for leveraging their unique optical properties, it highlights their pivotal role in driving innovation across photonic applications, facilitating transformative advancements in the field.

The chemical upcycling of waste plastics into high-value-added products such as monomers, fuels, or fine chemicals represents a promising strategy for mitigating the adverse effects of massive end-of-life plastics. Poly(bisphenol A carbonate) (BPA-PC) stands out as a notable engineering plastic due to its exceptional overall performance; however, its durability and potential environmental toxicity make its recycling imperative. Although a lot of reviews about plastic degradation have been done before our review, the progress for plastic degradation needs to be constantly updated and summarized due to the rapid development of this field. Meanwhile, BPA-PC, as an important notable engineering plastic, previous reviews only focused on its depolymerization into monomers and missed their further conversion into final chemicals. which In this concise review, we summarize recent developments in the chemical upcycling of BPA-PC to valuable chemicals, emphasizing the role of various catalysts and reagents. Some of the most utilized chemical upcycling strategies such as alcoholysis, aminolysis and upcycling of BPA-PC in “polymer-to-polymer” format to reproduce new polymers are elucidated in detail. Finally, we provide insights into the future prospects of chemical upcycling for waste BPA-PC.

The utilization of uranium (U) fission energy as a high-density, clean power source plays a pivotal role in mitigating greenhouse gas emissions. Uranium extraction from seawater exhibits superior environmental friendliness compared to terrestrial uranium mining, as it avoids substantial generation of radioactive waste and harmful chemicals. However, conventional adsorbents such as fiber, polymer, and biomass materials exhibit slow adsorption rates and low ion selectivity. Porous frameworks with large inner surface, full host-guest interaction, and site utilization are utilized to improve uranium absorption performance. Consequently, devising and synthesizing materials that enable efficient and cost-effective extraction of U(VI) from seawater poses a formidable challenge. Recently, there has been a considerable surge in academic interest regarding the synthesis and design of porous frameworks. By integrating experimental data, spectroscopic analysis, and theoretical calculations, we have conducted an extensive investigation into the actual performance, underlying principles, and practicality of conventional materials (such as fibers) and novel porous materials serving as adsorbents, photocatalysts, and electrocatalysts for U(VI) extraction from seawater.

An organocatalytic [4+2] annulation of N-sulfonyl ketimines with aminochalcones has been developed to afford the benzenesulfonamide fused tetrahydroquinazoline compounds under mild conditions with excellent stereoselectivity (up to 99% ee). This method provides a concise and efficient approach for the construction of N-heterocyclic compounds bearing 1,3-nonadjacent stereocenters with a quaternary carbon center.