Search

The design of efficient heterogeneous redox mediators with favorable affinity to substrate and electrolyte are much desired yet still challenging for the development of indirect electrolysis system. Herein, for the first time, we have developed a solid–liquid–gas three‐phase indirect electrolysis system based on a covalent organic framework (Dha−COF−Cu) as heterogeneous redox mediator for S−S coupling reaction. Dha−COF−Cu with the integration of high porosity, nanorod morphology, abundant hydroxyl groups and active Cu sites is much beneficial for the adsorption/activation of thiols, uniform dispersion and high wettability in electrolyte, and efficient interfacial electron transfer. Notably, Dha−COF−Cu as solid‐phase redox mediator exhibits excellent electrocatalytic efficiency for the formation of value‐added liquid‐phase S−S bond product (yields up to 99 %) coupling with the generation of gas‐phase product of H2 (~1.40 mmol g−1 h−1), resulting in a powerful three‐phase indirect electrolysis system. This is the first work about COFs that can be applied in three‐phase indirect electrolysis system, which might promote the development of porous crystalline materials in this field. [ABSTRACT FROM AUTHOR]

Covalent-organic frameworks (COFs) with photoinduced donor-acceptor (D-A) radical pairs show enhanced photocatalytic activity in principle. However, achieving long-lived charge separation in COFs proves challenging due to the rapid charge recombination. Here, we develop a novel strategy by combining [6 + 4] nodes to construct zyg -type 3D COFs, first reported in COF chemistry. This structure type exhibits a fused Olympic-rings-like shape, which provides a platform for stabilizing the photoinduced D-A radical pairs. The zyg -type COFs containing catalytically active moieties such as triphenylamine and phenothiazine (PTZ) show superior photocatalytic production rates of hydrogen peroxide (H2O2). Significantly, the photochromic radical states of these COFs show up to 400% enhancement in photocatalytic activity compared to the parent states, achieving a remarkable H2O2 synthesis rate of 3324 μmol g−1 h−1, which makes the PTZ-COF one of the best crystalline porous photocatalysts in H2O2 production. This work will shed light on the synthesis of efficient 3D COF photocatalysts built on topologies that can facilitate photogenerating D-A radical pairs for enhanced photocatalysis. [ABSTRACT FROM AUTHOR]

Precise design and tuning of Zn hopping/transfer sites with deeper understanding of the dendrite‐formation mechanism is vital in artificial anode protective coating for aqueous Zn‐ion batteries (AZIBs). Here, we probe into the role of anode‐coating interfaces by designing a series of anhydride‐based covalent organic frameworks (i.e. PI‐DP‐COF and PI‐DT‐COF) with specifically designed zigzag hopping sites and zincophilic anhydride groups that can serve as desired platforms to investigate the related Zn2+ hopping/transfer behaviours as well as the interfacial interaction. Combining theoretical calculations with experiments, the ABC stacking models of these COFs endow the structures with specific zigzag sites along the 1D channel that can accelerate Zn2+ transfer kinetics, lower surface‐energy, homogenize ion‐distribution or electric‐filed. Attributed to these superiorities, thus‐obtained optimal PI‐DT‐COF cells offer excellent cycling lifespan in both symmetric‐cell (2000 cycles at 60 mA cm−2) and full‐cell (1600 cycles at 2 A g−1), outperforming almost all the reported porous crystalline materials. [ABSTRACT FROM AUTHOR]

Visible‐light sensitive and bi‐functionally favored CO2 reduction (CRR)/evolution (CER) photocathode catalysts that can get rid of the utilization of ultraviolet light and improve sluggish kinetics is demanded to conquer the current technique‐barrier of traditional Li‐CO2 battery. Here, a kind of redox molecular junction sp2c metal‐covalent organic framework (i.e. Cu3‐BTDE‐COF) has been prepared through the connection between Cu3 and BTDE and can serve as efficient photocathode catalyst in light‐assisted Li‐CO2 battery. Cu3‐BTDE‐COF with redox‐ability, visible‐light‐adsorption region, electron‐hole separation ability and endows the photocathode with excellent round‐trip efficiency (95.2 %) and an ultralow voltage hysteresis (0.18 V), outperforming the Schiff base COFs (i.e. Cu3‐BTDA‐COF and Cu3‐DT‐COF) and majority of the reported photocathode catalysts. Combined theoretical calculations with characterizations, Cu3‐BTDE‐COF with the integration of Cu3 centers, thiazole and cyano groups possess strong CO2 adsorption/activation and Li+ interaction/diffusion ability to boost the CRR/CER kinetics and related battery property. [ABSTRACT FROM AUTHOR]

In modern industries, the aerobic oxidation of C(sp3)-H bonds to achieve the value-added conversion of hydrocarbons requires high temperatures and pressures, which significantly increases energy consumption and capital investment. The development of a light-driven strategy, even under natural sunlight and ambient air, is therefore of great significance. Here we develop a series of hetero-motif molecular junction photocatalysts containing two bifunctional motifs. With these materials, the reduction of O2 and oxidation of C(sp3)-H bonds can be effectively accomplished, thus realizing efficient aerobic oxidation of C(sp3)-H bonds in e.g., toluene and ethylbenzene. Especially for ethylbenzene oxidation reactions, excellent catalytic capacity (861 mmol g cat−1) is observed. In addition to the direct oxidation of C(sp3)-H bonds, CeBTTD-A can also be applied to other types of aerobic oxidation reactions highlighting their potential for industrial applications. The authors report a family of photocatalysts containing Ce active sites and perylene diimide ligands for the aerobic oxidation of substituted toluene, ethylbenzene, benzyl alcohol, thioanisole, and benzylamine in acetonitrile. [ABSTRACT FROM AUTHOR]