Qi Liu

Rechargeable Li | |SOCl₂•I₂ batteries, with their high specific energy, rely fundamentally on molecular catalysts to enable efficient redox processes. However, the inadequate accumulation of molecular catalysts at the positive electrode interface critically impairs their catalytic performance, especially under high specific capacity conditions. Herein, we propose to create localized high-concentration environments of molecular catalysts by using covalent organic frameworks with well-aligned pore structures and tailored functionality, which simultaneously enhance micropore accessibility (η = 82.6%) and capture ability (E_ads = −0.78 eV) of molecular catalyst, far surpassing conventional porous carbon (η = 38%, E_ads = −0.33 eV). This approach enables Li | |SOCl₂•I₂ battery to achieve stable 500 mAh/g over 1200 cycles and 2000 mAh/g over 80 cycles with an average Coulombic efficiency of up to 99.5%. Even at a low I₂ concentration of 7 mg/mL, the Li | |SOCl₂•I₂ battery using covalent organic frameworks delivers a high discharge capacity of 5000 mAh/g. The covalent organic frameworks-mediated localization of molecular catalysts enhances reaction kinetics and pathways, contributing to a substantial improvement in the overall performance of the Li | |SOCl₂•I₂ battery system.

Amorphous materials distinguish themselves from crystalline materials by lacking long-range order while retaining structural order at the local scale (2–5 Å). However, the complexity in topological and chemical order prevents current characterization tools from fully unveiling the structure in disordered materials. Consequently, the nature of medium-range order in amorphous materials has remained elusive. The Zachariasen and crystal competing models have been proposed to describe disordered phases and have both been verified through synthesis and characterization. The main difference between them is thought to be whether the amorphous phase shows medium-range order. Here we demonstrate a form of organized inorganic matter that is amorphous in two dimensions, while exhibiting long-range order and a high degree of crystallinity in the third. The structure consists of periodically stacked 2-dimensional amorphous Nb-W-O monolayers without long-range in-plane order. The unique periodic and therefore crystalline stacking along one principal axis enables direct imaging and revealed that the amorphous Nb-W-O monolayers formed in agreement with the Zachariasen model for 2 dimensions. Our findings show that the gap between crystalline and amorphous materials does not only depend on medium-range order but can also apply to principal dimensions within the same solid.

Understanding the kinetics of solid-state chemical reactions is critical for elucidating reaction mechanisms and enabling the rational design of functional materials. However, such investigations are often impeded by limited molecular mobility, restricted reactant interactions, and complex nucleation phenomena. In this study, we employ one-dimensional crystalline coordination polymers (CPs) as structurally ordered platforms to investigate the kinetics of [2 + 2] photocycloaddition reactions of embedded alkene substrates. By integrating nuclear magnetic resonance, fluorescence spectroscopy, laser scanning confocal microscopy, and theoretical calculations, we demonstrate that the electronegativity of substituents (-F, -Cl, -Br, -I) on carboxylate ligands strongly modulates reaction rates, with more electronegative groups accelerating the kinetics. Additionally, single-crystal CPs exhibit significantly enhanced reaction rates compared to stacked crystals, attributed to uniform light penetration and reduced spatial inhomogeneity. These findings position CPs as robust model systems for probing heterogeneous reaction kinetics and offer a new framework for understanding and optimizing olefin reactivity in solid-state environments.

Rechargeable Li-Cl₂ batteries are a promising high-energy-density technology but having critical challenges of limited rates and capacities. Insufficient and uneven ion flux in the interior of cathode is a crucial factor that hinders the rate performance and specific capacity of Li-Cl₂ battery. Herein, we propose and develop hollow carbon nanoreactors (HCNRs) as cathode materials for extremely high-power and high-energy Li-Cl₂ batteries. By confining electrolytes within tailored cavities, HCNRs facilitate enhanced and spatially homogenized ion flux in the interior of cathode, eliminating the reliance on bulk electrolyte diffusion and prohibiting rapid electrode degradation. This design enables the as-assembled Li-Cl₂ cell to achieve an ultrahigh current density of 120 mA/cm² during the charge/discharge process (charging to 500 mAh/g in 15 s) and a record-breaking specific capacity of 8000 mAh/g (9 mAh/cm²), superior to the reported literature. Furthermore, we demonstrate the scalability of this design in a 1-Ah-scale pouch cell, achieving a practical cell-specific energy of 106 Wh/kg. This hollow nanoreactor design highlights the potential of Li-Cl₂ batteries as high-power and energy-dense systems, paving the way for their practical applications.

Developing versatile crystalline platforms can significantly enhance the utility of time-resolved X-ray crystallography for observing diverse reaction mechanisms ^1–6 . However, it is often limited by its inability to handle ultrafast and complex reactions. Here we propose a coordination polymer single-crystal platform that incorporates flexible cluster nodes and integrated reaction substrates. This advanced platform features enhanced diffraction capabilities and adaptability to substrate changes, enabling the observation of ultrafast, highly dynamic reactions involving multiple pathways and intermediates. By combining this platform with a cryo-assisted strategy, we investigate a complicated ultrafast photochemical cycloaddition reaction with five transient intermediates and three distinct routes, which are rationalized through theoretical calculations. Our findings underscore the feasibility of employing this enhanced single-crystal platform to unravel elusive reaction mechanisms, presenting a promising approach with broad applicability.

The synthesis of MOFs in a two-dimensional (2D) film morphology is attractive for several applications including molecular and ionic separation. However, 2D MOFs have only been reported from structures that crystallize in lamellar morphology, where layers are held together by van der Waals (vdW) interaction. By comparison, UiO-66, one of the most studied MOFs because of its exceptional chemical stability, has only been reported in three-dimensional (3D) morphology. 2D UiO-66 is challenging to obtain given the robust isotropic bonds in its cubic crystal structure. Herein, we report the first synthesis of non-vdW 2D UiO-66-NH₂ by developing crystal growth conditions that promote in-plane growth over out-of-plane growth. Continuous, oriented UiO-66-NH₂ film with thickness tunable in the range of 0.5 to 2 unit cells could be obtained by sustainable, scalable chemistry, which yielded attractive ion-ion selectivity. The preparation of non-vdW 2D MOF is highly attractive to advance the field of MOF films for diverse applications.