The functionalization of three-dimensional (3D) covalent organic frameworks (COFs) is essential to broaden their applications. However, the introduction of organic groups with electroactive abilities into 3D COFs is still very limited. Herein we report the first case of 3D tetrathiafulvalene-based COFs (3D-TTF-COFs) with non- or 2-fold interpenetrated pts topology and tunable electrochemical activity. The obtained COFs show high crystallinity, permanent porosity, and large specific surface area (up to 3000 m2/g). Furthermore, these TTF-based COFs are redox active to form organic salts that exhibit tunable electric conductivity (as high as 1.4 × 10–2 S cm–1 at 120 °C) by iodine doping. These results open a way toward designing 3D electroactive COF materials and promote their applications in molecular electronics and energy storage.

The electrochemical double‐layer capacitors (EDLCs) are highly demanded electrical energy storage devices due to their high power density with thousands of cycle life compared with pseudocapacitors and batteries. Herein, a series of capacitor cells composed of exfoliated mesoporous 2D covalent organic frameworks (e‐COFs) that are able to perform excellent double‐layer charge storage is reported. The selected mesoporous 2D COFs possess eclipsed AA layer‐stacking mode with 3.4 nm square‐like open channels, favorable BET surface areas (up to 1170 m2 g−1), and high thermal and chemical stabilities. The COFs via the facile, scalable, and mild chemical exfoliation method are further exfoliated to produce thin‐layer structure with average thickness of about 22 nm. The e‐COF‐based capacitor cells achieve high areal capacitance (5.46 mF cm−2 at 1,000 mV s−1), high gravimetric power (55 kW kg−1), and relatively low τ0 value (121 ms). More importantly, they perform nearly an ideal DL charge storage at high charge–discharge rate (up to 30 000 mV s−1) and maintain almost 100% capacitance stability even after 10 000 cycles. This study thus provides insights into the potential utilization of COF materials for EDLCs.

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Developing functionalized 3D covalent organic frameworks (3D COFs) is critical to broaden their potential applications. However, the introduction of specific functionality in 3D COFs remains a great challenge because most of the functional groups are not compatible with the synthesis conditions. Herein, for the first time 3D thioether‐based COFs (JUC‐570 and JUC‐571) for mercury (Hg2+) removal from aqueous solution is reported. These 3D thioether‐based COFs prepared by the bottom‐up approach display high Hg2+ uptakes (972 mg g−1 for JUC‐570 and 970 mg g−1 for JUC‐571 at pH = 5), fast adsorption kinetics (distribution coefficient Kd value of 2.29 × 107 mL g−1 for JUC‐570 and 2.07 × 107 mL g−1 for JUC‐571), and favorable selectivity. In particular, JUC‐570 is periodically decorated with isopropyl groups around imine bonds that markedly improve its chemical stability and effectively prevent the pore collapse, and thus endows high Hg2+ adsorption capacity (619 mg g−1) and excellent cycle performance even at pH = 1. This study not only puts forward a new route to construct stable functionalized 3D COFs, but also promotes their potential applications in areas related to the environment.

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