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Conjugated coordination polymers (c‐CPs) are unique organic–inorganic hybrid semiconductors with intrinsically high electrical conductivity and excellent charge carrier mobility. However, it remains a challenge in tailoring electronic structures, due to the lack of clear guidelines. Here, we develop a strategy wherein controlling the redox state of hydroquinone/benzoquinone (HQ/BQ) ligands allows for the modulation of the electronic structure of c‐CPs while maintaining the structural topology. The redox‐state control is achieved by reacting the ligand TTHQ (TTHQ=1,2,4,5‐tetrathiolhydroquinone) with silver acetate and silver nitrate, yielding Ag4TTHQ and Ag4TTBQ (TTBQ=1,2,4,5‐tetrathiolbenzoquinone), respectively. In spite of sharing the same topology consisting of a two‐dimensional Ag−S network and HQ/BQ layer, they exhibit different band gaps (1.5 eV for Ag4TTHQ and 0.5 eV for Ag4TTBQ) and conductivities (0.4 S/cm for Ag4TTHQ and 10 S/cm for Ag4TTBQ). DFT calculations reveal that these differences arise from the ligand oxidation state inhibiting energy band formation near the Fermi level in Ag4TTHQ. Consequently, Ag4TTHQ displays a high Seebeck coefficient of 330 μV/K and a power factor of 10 μW/m ⋅ K2, surpassing Ag4TTBQ and the other reported silver‐based c‐CPs. Furthermore, terahertz spectroscopy demonstrates high charge mobilities exceeding 130 cm2/V ⋅ s in both Ag4TTHQ and Ag4TTBQ. [ABSTRACT FROM AUTHOR]

Two‐dimensional conjugated metal–organic frameworks (2D c‐MOFs) are emerging as a unique subclass of layer‐stacked crystalline coordination polymers that simultaneously possess porous and conductive properties, and have broad application potential in energy and electronic devices. However, to make the best use of the intrinsic electronic properties and structural features of 2D c‐MOFs, the controlled synthesis of hierarchically nanostructured 2D c‐MOFs with high crystallinity and customized morphologies is essential, which remains a great challenge. Herein, we present a template strategy to synthesize a library of 2D c‐MOFs with controlled morphologies and dimensions via insulating MOFs‐to‐c‐MOFs transformations. The resultant hierarchically nanostructured 2D c‐MOFs feature intrinsic electrical conductivity and higher surface areas than the reported bulk‐type 2D c‐MOFs, which are beneficial for improved access to active sites and enhanced mass transport. As proof‐of‐concept applications, the hierarchically nanostructured 2D c‐MOFs exhibit a superior performance for electrical properties related applications (hollow Cu‐BHT nanocubes‐based supercapacitor and Cu‐HHB nanoflowers‐based chemiresistive gas sensor), achieving over 225 % and 250 % improvement in specific capacity and response intensity over the corresponding bulk type c‐MOFs, respectively. [ABSTRACT FROM AUTHOR]

Electrochemical proton storage plays an essential role in designing next‐generation high‐rate energy storage devices, e.g., aqueous batteries. Two‐dimensional conjugated covalent organic frameworks (2D c‐COFs) are promising electrode materials, but their competitive proton and metal‐ion insertion mechanisms remain elusive, and proton storage in COFs is rarely explored. Here, we report a perinone‐based poly(benzimidazobenzophenanthroline) (BBL)‐ladder‐type 2D c‐COF for fast proton storage in both a mild aqueous Zn‐ion electrolyte and strong acid. We unveil that the discharged C−O− groups exhibit largely reduced basicity due to the considerable π‐delocalization in perinone, thus affording the 2D c‐COF a unique affinity for protons with fast kinetics. As a consequence, the 2D c‐COF electrode presents an outstanding rate capability of up to 200 A g−1 (over 2500 C), surpassing the state‐of‐the‐art conjugated polymers, COFs, and metal–organic frameworks. Our work reports the first example of pure proton storage among COFs and highlights the great potential of BBL‐ladder‐type 2D conjugated polymers in future energy devices. [ABSTRACT FROM AUTHOR]

Two‐dimensional conjugated metal–organic frameworks (2D c‐MOFs) are emerging as a unique class of electronic materials. However, 2D c‐MOFs with band gaps in the Vis‐NIR and high charge carrier mobility are rare. Most of the reported conducting 2D c‐MOFs are metallic (i.e. gapless), which largely limits their use in logic devices. Herein, we design a phenanthrotriphenylene‐based, D2h‐symmetric π‐extended ligand (OHPTP), and synthesize the first rhombic 2D c‐MOF single crystals (Cu2(OHPTP)). The continuous rotation electron diffraction (cRED) analysis unveils the orthorhombic crystal structure at the atomic level with a unique slipped AA stacking. The Cu2(OHPTP) is a p‐type semiconductor with an indirect band gap of ≈0.50 eV and exhibits high electrical conductivity of 0.10 S cm−1 and high charge carrier mobility of ≈10.0 cm2 V−1 s−1. Theoretical calculations underline the predominant role of the out‐of‐plane charge transport in this semiquinone‐based 2D c‐MOF. [ABSTRACT FROM AUTHOR]

2D conjugated metal–organic frameworks (2D c‐MOFs) are emerging as electroactive materials for chemiresistive sensors, but selective sensing with fast response/recovery is a challenge. Phthalocyanine‐based Ni2[MPc(NH)8] 2D c‐MOF films are presented as active layers for polarity‐selective chemiresisitors toward water and volatile organic compounds (VOCs). Surface‐hydrophobic modification by grafting aliphatic alkyl chains on 2D c‐MOF films decreases diffused analytes into the MOF backbone, resulting in a considerably accelerated recovery progress (from ca. 50 to ca. 10 s) during humidity sensing. Toward VOCs, the sensors deliver a polarity‐selective response among alcohols but no signal for low‐polarity aprotic hydrocarbons. The octadecyltrimethoxysilane‐modified Ni2[MPc(NH)8] based sensor displays high‐performance methanol sensing with fast response (36 s)/recovery (13 s) and a detection limit as low as 10 ppm, surpassing reported room‐temperature chemiresistors. [ABSTRACT FROM AUTHOR]

Highly effective electrocatalysts promoting CO2 reduction reaction (CO2RR) is extremely desirable to produce value-added chemicals/fuels while addressing current environmental challenges. Herein, we develop a layer-stacked, bimetallic two-dimensional conjugated metal-organic framework (2D c-MOF) with copper-phthalocyanine as ligand (CuN4) and zinc-bis(dihydroxy) complex (ZnO4) as linkage (PcCu-O8-Zn). The PcCu-O8-Zn exhibits high CO selectivity of 88%, turnover frequency of 0.39 s−1 and long-term durability (>10 h), surpassing thus by far reported MOF-based electrocatalysts. The molar H2/CO ratio (1:7 to 4:1) can be tuned by varying metal centers and applied potential, making 2D c-MOFs highly relevant for syngas industry applications. The contrast experiments combined with operando spectroelectrochemistry and theoretical calculation unveil a synergistic catalytic mechanism; ZnO4 complexes act as CO2RR catalytic sites while CuN4 centers promote the protonation of adsorbed CO2 during CO2RR. This work offers a strategy on developing bimetallic MOF electrocatalysts for synergistically catalyzing CO2RR toward syngas synthesis. Effective electrocatalyst is crucial in promoting CO2 reduction to address current energy/environmental issue. Here, the authors develop bimetallic layered two-dimensional conjugated metal-organic framework to synergistically and efficiently electro-catalyze CO2 to CO toward syngas synthesis. [ABSTRACT FROM AUTHOR]