2D conductive metal–organic frameworks (2D c‐MOFs) are promising candidates for efficient electrocatalysts for the CO2 reduction reaction (CO2RR). A nitrogen‐rich tricycloquinazoline (TQ) based multitopic catechol ligand was used to coordinate with transition‐metal ions (Cu2+ and Ni2+), which formed 2D graphene‐like porous sheets: M3(HHTQ)2 (M=Cu, Ni; HHTQ=2,3,7,8,12,13‐Hexahydroxytricycloquinazoline). M3(HHTQ)2 can be regarded as a single‐atom catalyst where Cu or Ni centers are uniformly distributed in the hexagonal lattices. Cu3(HHTQ)2 exhibited superior catalytic activity towards CO2RR in which CH3OH is the sole product. The Faradic efficiency of CH3OH reached up to 53.6 % at a small over‐potential of −0.4 V. Cu3(HHTQ)2 exhibited larger CO2 adsorption energies and higher activities over the isostructural Ni3(HHTQ)2 and the reported archetypical Cu3(HHTP)2. There is a strong dependence of both metal centers and the N‐rich ligands on the electrocatalytic performance.

The intrinsic hydrophobicity and limited light absorption especially in the near‐infrared (NIR) region of porous organic polymers are two bottlenecks impeding their applications in solar steam generation (SSG). Herein, we develop a 1,4,5,8‐tetrakis(phenylamino)anthracene‐9,10‐dione (TPAD)‐based covalent organic framework (COF) (TPAD‐COF) featuring both superhydrophilicity and broad light absorption covering from the entire UV/Vis to NIR regions for SSG. TPAD‐COF serving as a highly efficient photothermal conversion material without any additives displays an excellent water evaporation of 1.42 kg m−2 h−1 and achieves a high energy conversion efficiency of 94 % under 1 sun irradiation. Further extension of the light absorption range of the TPAD‐based COF is realized through post‐synthetic modification by chelating BF2 moieties. Systematic control experiments and analysis confirm that the hydrophilicity of photothermal conversion materials plays a more dominant role in the current TPAD‐based COFs for SSG.

Metrics & MoreArticle Recommendations CONSPECTUS: Covalent organic frameworks (COFs) are an emerging class of crystalline porous polymers and have received tremendous attention and research interest. COFs can be classified into two-dimensional (2D) and three-dimensional (3D) analogues. Resembling the architectures of porous graphene, 2D conjugated COFs have exhibited promising prospects in many fields, such as gas storage and separation, heterogeneous catalysis, sensing, photocatalysis, environmental remediation, drug delivery, energy storage and conversion, and so forth. However, efficient structural design for high-throughput production of crystalline 2D COFs remains challenging.In this Account, we summarize our recent contributions to the design, synthesis, and application exploration of 2D conjugated COFs. First, we raised an efficient "two-inone" strategy for the facile synthesis of 2D imine COFs with good reproducibility and solvent adaptability. Thanks to this elaborate molecular design strategy, we could easily modulate the topology of COFs and fabricate COF films. In addition, we developed two approaches to stabilize the 2D conjugated COFs by using planar building blocks and donor−acceptor structures. We also proposed a skeleton engineering strategy to design COFs as electrode materials, through which redox-active orthoquinone moieties were stepwise-incorporated in the skeletons of isostructural 2D imine-linked COFs. This strategy enabled systematic investigations on a series of 2D conjugated COFs with analogous structures but different numbers of active sites for energy storage, which provides a good platform to unveil the underlying structure−property relationships. In addition, we recently developed a new kind of arylamine-linked 2D conjugated COFs. The electroactive diphenylamine linkages endowed these 2D conjugated COFs with extended conjugation and improved stability, which also conferred these COFs with excellent pseudocapacitive energy storage performance. Moreover, tailor-made sulfur-rich COFs were introduced that were synthesized by selective introduction of polysulfide or sulfonyl groups on the COF skeletons and were used for Li storage and proton conduction. At the end, the key challenges of 2D conjugated COFs toward practical applications and their future prospects are suggested. We hope that this Account will evoke new inspirations and innovative work in the field of 2D conjugated COFs in the near future, especially in some burgeoning and interdisciplinary research areas.

High-efficiency surface plasmon enhanced 1,1-bis-(4-bis(4-methyl-phenyl)-amino-phenyl)-cyclohexane:C70 small molecular bulk heterojunction organic solar cells with a MoO3 anode buffer layer have been demonstrated. The optimized device based on thermal evaporated Ag nanoparticles (NPs) shows a power conversion efficiency of 5.42%, which is 17% higher than the reference device. The improvement is attributed to both the enhanced conductivity and increased absorption due to the near-field enhancement of the localized surface plasmon resonance of Ag NPs.