The irrational use of sulfonylurea herbicides (SUHs) has brought many environmental problems due to their long-term residue and toxicity on non-target organisms. In this study, oxygen-defective graphdiyne (GDY) was applied as an adsorption material to remove pesticides from water for the first time under various conditions and exhibited remarkable adsorption properties for seven SUHs. The maximum adsorption capacity of GDY reached up to 795.51 mg/g for iodosulfuron-methyl sodium, which was over 130 times higher than that of modified graphene oxide (6 mg/g) and modified biochar (1.5 mg/g) reported by others. Additionally, the pseudo-second-order kinetic model and Langmuir isotherm model were well fitted for the experimental data. The thermodynamic results revealed that the adsorption process was physical, spontaneous and endothermic in nature. Further studies verified that π-π interaction, hydrophobic interaction and hydrogen bonding played an important role in SUHs adsorption on GDY. This work clarifies that oxygen-defective GDY is an ultra-efficient, sustainable and anti-interference adsorbent for the removal of SUHs from aqueous solution. 

Oxygen-defective graphdiyne for ultra-efficient removal of sulfonylurea herbicides from aqueous solution

Bridging Heterogeneous and Homogeneous Catalysts by Ultrathin Metal-polyphthalocyanine-Based Nanosheets from Electron-Coupled Transalkylation Delamination

Photocorrosion of highly active photocatalysts is an urgent problem to be solved in the field of photocatalysis; however, searching for effective strategies for inhibiting photocorrosion of photocatalysts is still a grand challenge. Herein, we design and construct a class of Cu2O/2D PyTTA-TPA COFs (PyTTA: 1,3,6,8-Tetrakis(4-aminophenyl)pyrene, TPA: p-benzaldehyde) core/shell nanocubes to greatly boost the performance of photocatalytic hydrogen evolution and significantly inhibit the photocorrosion. The optimal Cu2O/PyTTA-TPA COFs core/shell nanocubes exhibit an excellent photocatalytic H2 evolution rate of 12.5 mmol h-1 g-1, which is ∼8.0-fold and ∼20.0-fold higher than those of PyTTA-TPA COFs and Cu2O nanocube, respectively, and also is the best in all the reported metal oxides catalytic materials. The mechanism studies demonstrate that the appropriate matching band gaps and tight integration of PyTTA-TPA COFs and Cu2O nanocubes can significantly facilitate the separation of photogenerated electron-hole pairs in the Cu2O/PyTTA-TPA COFs core/shell nanocube during the photocatalytic process, which ameliorates the photocatalytic H2 evolution activity. Most importantly, the 2D PyTTA-TPA COFs shell with outstanding intrinsic stability protects Cu2O nanocubes core from photocorrosion by showing no morphology and crystal structure change after 1000 times of photoexcitation.

Cu2O/2D COFs Core/Shell Nanocubes with Antiphotocorrosion Ability for Efficient Photocatalytic Hydrogen Evolution.

Two-dimensional covalent organic frameworks (2D COFs) feature graphene-type 2D layered sheets but with a tunable structure, electroactivity, and high porosity. If these traits are well-combined, then 2D COFs can be applied in electronics to realize functions with a high degree of complexity. Here, a highly crystalline electroactive COF, BDFamide-Tp, was designed and synthesized. It shows regularly distributed pores with a width of 1.35 nm. Smooth and successive films of such a COF were fabricated and found to be able to increase the conductivity of an organic semiconductor by 103 by interfacial doping. Upon encapsulation of a photoswitchable molecule (spiropyran) into the voids of the COF layer, the resulted devices respond differently to light of different wavelengths. Specifically, the current output ratio after UV vs Vis illumination reaches 100 times, thus effectively creating on and off states. The respective positive and negative feedbacks are memorized by the device and can be reprogrammed by UV/Vis illumination. The reversible photostimulus responsivity and reliable memory of the device are derived from the combination of electroactivity and porosity of the 2D COF. This work shows the capability of 2D COFs in higher-level electronic functions and extends their possible applications in information storage.

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Electroactive Covalent Organic Framework Enabling Photostimulus-Responsive Devices

Two-dimensional and pseudo-2D systems come in various forms. Membranes separating protocells from the environment were necessary for life to occur. Later, compartmentalization allowed for the development of more complex cellular structures. Nowadays, 2D materials (e.g., graphene, molybdenum disulfide) are revolutionizing the smart materials industry. Surface engineering allows for novel functionalities, as only a limited number of bulk materials have the desired surface properties. This is realized via physical treatment (e.g., plasma treatment, rubbing), chemical modifications, thin film deposition (using both chemical and physical methods), doping and formulation of composites, or coating. However, artificial systems are usually static. Nature creates dynamic and responsive structures, which facilitates the formation of complex systems. The challenge of nanotechnology, physical chemistry, and materials science is to develop artificial adaptive systems. Dynamic 2D and pseudo-2D designs are needed for future developments of life-like materials and networked chemical systems in which the sequences of the stimuli would control the consecutive stages of the given process. This is crucial to achieving versatility, improved performance, energy efficiency, and sustainability. Here, we review the advancements in studies on adaptive, responsive, dynamic, and out-of-equilibrium 2D and pseudo-2D systems composed of molecules, polymers, and nano/microparticles.

/pdf/adaptive-2d-and-pseudo-2d-systems-molecular-polymeric-and-29r3jkji.pdf

Adaptive 2D and Pseudo-2D Systems: Molecular, Polymeric, and Colloidal Building Blocks for Tailored Complexity

Covalent organic frameworks (COFs) can exhibit high specific surface area and catalytic activity, but traditional solution-based synthesis methods often lead to insoluble and infusible powders or fragile films on solution surface. Herein we report large-area -C=N- linked two-dimensional (2D) COF films with controllable thicknesses via vapor induced conversion in a chemical vapor deposition (CVD) system. The assembly process is achieved by reversible Schiff base polycondensation between PyTTA film and TPA vapor, which results in a uniform organic framework film directly on growth substrate, and is driven by π-π stacking interactions with the aid of water and acetic acid. Wafer-scale 2D COF films with different structures have been successfully synthesized by adjusting their building blocks, suggesting its generic applicability. The carrier mobility of PyTTA-TPA COF films can reach 1.89 × 10-3 cm2 V-1 s-1. When employed as catalysts in hydrogen evolution reaction (HER), they show high electrocatalytic activity compared with metal-free COFs or even some metallic catalysts. Our results represent a versatile route for the direct construction of large-area uniform 2D COF films on substrates towards multi-functional applications of 2D π-conjugated systems. 

/pdf/two-dimensional-covalent-organic-framework-films-prepared-on-19q1gfc9.pdf

Two-dimensional covalent organic framework films prepared on various substrates through vapor induced conversion

Conductive metal-organic frameworks (MOFs) have performed well in the fields of energy and catalysis, among which two-dimensional (2D) and three-dimensional (3D) MOFs are well-known. Here, we have synthesized a one-dimensional (1D) conductive metal-organic framework (MOF) in which hexacoordinated 1,5-Diamino-4,8-dihydroxy-9,10-anthraceneedione (DDA) ligands are connected by double Cu ions, resulting in nanoribbon layers with 1D π-d conjugated nanoribbon plane and out-of-plane π-π stacking, which facilitates charge transport along two dimensions. The DDA-Cu as a highly conductive n-type MOF has high crystalline quality with a conductivity of ~ 9.4 S·m-1, which is at least two orders of magnitude higher than that of conventional 1D MOFs. Its electrical band gap (Eg) and exciton binding energy (Eb) are approximately 0.49 eV and 0.3 eV, respectively. When utilized as electrode material in a supercapacitor, the DDA-Cu exhibits good charge storage capacity and cycle stability. Meanwhile, as thse active semiconductor layer, it successfully simulates the artificial visual perception system with excellent bending resistance and air stability as a MOF-based flexible optoelectronic synaptic case. The controllable preparation of high-quality 1D DDA-Cu MOF may enable new architectural designs and various applications in the future. 

/pdf/a-one-dimensional-conductive-metal-organic-framework-with-39vc0pq7.pdf

A one-dimensional conductive metal-organic framework with extended π-d conjugated nanoribbon layers

Tuning Fe-Spin State of Fen4 Structure by Axial Bonds as Efficient Catalyst in Li-S Batteries

Covalent organic frameworks (COFs) are at the forefront of porous material research due to their crystallinity and topological diversity. However, most COFs are connected by reversible chemical bonds, which limit their applications under harsh conditions. Herein, we develop a novel synthetic method to lock the imine bond using amino groups via a precursor-involved cascade reaction. We experimentally demonstrated that the nucleation process of COFs can be controlled by precursor hydrolysis. A family of crystalline two-dimensional tribenzimidazole-based COFs (2D BI-COFs) was prepared by the condensation of o-phenylenediamine derivative and aryl aldehydes. Their structures were confirmed by powder X-ray diffraction, Fourier-transform infrared spectroscopy, and solid-state 13C cross-polarization magic angle spinning nuclear magnetic resonance (CP/MAS NMR) spectroscopy. They showed high surface areas, good CO2 uptake capacities, excellent CO2/N2 selectivities, and high chemical stabilities. Of these materials, BI-COF-1 was an efficient photocatalyst for the visible-light-driven photocatalytic oxidation of sulfides, which displayed high conversion (∼100%) and excellent selectivity (>90%). We believe that our study can provide new insights into the synthesis of 2D chemical-stable COFs. 

Controlling the Nucleation Process to Prepare a Family of Crystalline Tribenzimidazole-Based Covalent Organic Frameworks

Two-dimensional materials (2DMs) with extraordinary electronic and optical properties have attracted great interest in optoelectronic applications. Due to their atomically thin feature, 2DM-based devices are generally sensitive to oxygen and moisture in ambient air, and thus, practical application of durable 2DM-based devices remains challenging. Here, we report a novel strategy to directly synthesize amorphous BN film on various 2DMs and field-effect transistor (FET) devices at low temperatures by conventional chemical vapor deposition. The wafer-scale BN film with controllable thickness serves as a passivation and heat dissipation layer, further improving the long-term stability, the resistance to laser irradiation, and the antioxidation performance of the underneath 2DMs. In particular, the BN capping layer could be deposited directly on a WSe2 FET at low temperature to achieve a clean and conformal interface. The high performance of the BN-capped WSe2 device is realized with suppressed current fluctuations and 10-fold enhanced carrier mobility. The transfer-free amorphous BN synthesis technique is simple and applicable to various 2DMs grown on arbitrary substrates, which shows great potential for applications in future two-dimensional electronics.

Low-Temperature Synthesis of Boron Nitride as a Large-Scale Passivation and Protection Layer for Two-Dimensional Materials and High-Performance Devices.

Jichen Dong

Papers

Two-dimensional covalent organic framework films prepared on various substrates through vapor induced conversion

A one-dimensional conductive metal-organic framework with extended π-d conjugated nanoribbon layers

Tuning Fe-Spin State of Fen4 Structure by Axial Bonds as Efficient Catalyst in Li-S Batteries

Controlling the Nucleation Process to Prepare a Family of Crystalline Tribenzimidazole-Based Covalent Organic Frameworks

Low-Temperature Synthesis of Boron Nitride as a Large-Scale Passivation and Protection Layer for Two-Dimensional Materials and High-Performance Devices.