Organic electrode materials are of long‐standing interest for next‐generation sustainable lithium‐ion batteries (LIBs). As a promising cathode candidate, imide compounds have attracted extensive attention due to their low cost, high theoretical capacity, high working voltage, and fast redox reaction. However, the redox active site utilization of imide electrodes remains challenging for them to fulfill their potential applications. Herein, the synthesis of a highly stable, crystalline 2D polyarylimide (2D‐PAI) integrated with carbon nanotube (CNT) is demonstrated for the use as cathode material in LIBs. The synthesized polyarylimide hybrid (2D‐PAI@CNT) is featured with abundant π‐conjugated redox‐active naphthalene diimide units, a robust cyclic imide linkage, high surface area, and well‐defined accessible pores, which render the efficient utilization of redox active sites (82.9%), excellent structural stability, and fast ion diffusion. As a consequence, high rate capability and ultrastable cycle stability (100% capacity retention after 8000 cycles) are achieved in the 2D‐PAI@CNT cathode, which far exceeds the state‐of‐the‐art polyimide electrodes. This work may inspire the development of novel organic electrodes for sustainable and durable rechargeable batteries.

Despite the recent progress in the synthesis of crystalline boronate ester covalent organic frameworks (BECOFs) in powder and thin‐film through solvothermal method and on‐solid‐surface synthesis, respectively, their applications in electronics, remain less explored due to the challenges in thin‐film processability and device integration associated with the control of film thickness, layer orientation, stability and crystallinity. Moreover, although the crystalline domain sizes of the powder samples can reach micrometer scale (up to ≈1.5 μm), the reported thin‐film samples have so far rather small crystalline domains up to 100 nm. Here we demonstrate a general and efficient synthesis of crystalline two‐dimensional (2D) BECOF films composed of porphyrin macrocycles and phenyl or naphthyl linkers (named as 2D BECOF‐PP or 2D BECOF‐PN) by employing a surfactant‐monolayer‐assisted interfacial synthesis (SMAIS) on the water surface. The achieved 2D BECOF‐PP is featured as free‐standing thin film with large single‐crystalline domains up to ≈60 μm2 and tunable thickness from 6 to 16 nm. A hybrid memory device composed of 2D BECOF‐PP film on silicon nanowire‐based field‐effect transistor is demonstrated as a bio‐inspired system to mimic neuronal synapses, displaying a learning–erasing–forgetting memory process.

Covalent organic frameworks (COFs) have garnered immense scientific interest among porous materials because of their structural tunability and diverse properties. However,the response of such materials towardlaser-induced nonlinear optical (NLO) applications is hardly understood and demands prompt attention. Three novel regioregular porphyrin (Por)-based porous COFs-Por-COF-HH and its dual metalated congeners Por-COF-ZnCu and Por-COF-ZnNi-have been prepared and present excellent NLO properties.N otably,i ntensity-dependent NLO switching behavior was observed for these Por-COFs,w hichi sh ighly desirable for optical switching and optical limiting devices. Moreover,t he efficient p-conjugation and charge-transfer transition in ZnCu-Por-COF enabled ahigh nonlinear absorption coefficient (b = 4470 cm/GW) and figure of merit (FOM = s 1 /s o ,3565) value compared to other state-of-the-art materials, including molecular porphyrins (b % 100-400 cm/GW), metalorganic frameworks (MOFs; b % 0.3-0.5 cm/GW), and graphene (b = 900 cm/GW). Molecules/materialswithinherentnonlinearoptical(NLO)properties have profound importance in telecommunications, data storage,d isplay technologies,s ensors,a nd biomedical devices. [1] In this regard, molecular porphyrins have been widely studied because of their versatile optical and electrochemical properties,large and fast NLO responses,possibility of incorporating aw ide range of metals,a nd their good thermochemical stabilities for optical limiting and optical switching applications. [2] Nonetheless,t oenhance and tune optical nonlinearities of singular porphyrin moieties,b athochromic shifting of their absorption bands by large p-electron delocalization is crucial, which becomes possible through de novo design of integrated porphyrin units featuring extended p-conjugation. [3, 4] Along this line,w ep ropose ap orphyrin-linked covalent organic framework (COF) [5] as model system, wherein enhancement and switching of the NLO response can be studied by manipulation of the framework. Among the recognized crystalline materials, COFs are known for being mechanically robust and offering ahighly accessible surface area. Thestructural and electronic tunability of COFs have garnered particular interest in research areas such as adsorption/storage, [6] chemical sensors, [7] electronics, [8] and catalysis. [9] Despite such potential, COFs comprising porphyrin units have not been explored as NLO materials.F or this purpose,aregioregular ordering of multiple metal centers in ac rystalline 2D porphyrin framework-preferably without ap ost-synthetic modification-is desirable.T his challenging objective [10] has great potential in optoelectronics and photo/electrocatalysis applications.Herein, we present aconjugated imine-linked porphyrinhomopolymeric COF (Por-COF-HH; Figure 1a)prepared by Schiff base A4B4 condensation of 5,10,15,20-tetrakis(4-formylphenyl)-21H,23H-porphyrin (TFPP) and 5,10,15,20-tetrakis(4-aminophenyl)-21H,23H-porphyrin (TAPP). Adopting the same pathway,w ea lso synthesized regioregular...

Cyano‐substituted polyphenylene vinylenes (PPVs) have been the focus of research for several decades owing to their interesting optoelectronic properties and potential applications in organic electronics. With the advent of organic two‐dimensional (2D) crystals, the question arose as to how the chemical and optoelectronic advantages of PPVs evolve in 2D compared with their linear counterparts. In this work, we present the efficient synthesis of two novel 2D fully sp2‐carbon‐linked crystalline PPVs and investigate the essentiality of inorganic bases for their catalytic formation. Notably, among all bases screened, cesium carbonate (Cs2CO3) plays a crucial role and enables reversibility in the first step with subsequent structure locking by formation of a C=C double bond to maintain crystallinity, which is supported by density functional theory (DFT) calculations. A quantifiable energy diagram of a “quasi‐reversible reaction” is proposed, which allows the identification of further suitable C−C bond formation reactions for 2D polymerizations. Moreover, the narrowing of the HOMO–LUMO gap is delineated by expanding the conjugation into two dimensions. To enable environmentally benign processing, the post‐modification of 2D PPVs is further performed, which renders stable dispersions in the aqueous phase.

The interest in (micro)porous systems is greater than ever before with microporous polymers finding application in areas such as gas storage/separation and catalysis. In contrast to the vast majority of publications on microporous polymers seeking ever higher values for surface area or uptake capacity for a particular gas, this work presents a means to render a microporous system responsive to electromagnetic stimuli. The incorporation of a diarylethene (DAE) derivative in the backbone of a polymer of intrinsic microporosity (PIM) produces a microporous system that exhibits photochromism as proven by UV−vis absorption and NMR studies. In the resulting DAE-PIM, surface area is not a fixed unalterable property but can be influenced by the external and nondestructive stimulus light in a reversible manner. Furthermore, in combination with Matrimid, free-standing membranes can be produced that display light-switchable diffusivity and permeability for carbon dioxide and oxygen. In this way, material scientists are offered the potential to employ only one system that can assume several states with different properties for each.

Despite the recent progress in the synthesis of crystalline boronate ester covalent organic frameworks (BECOFs) in powder and thin‐film through solvothermal method and on‐solid‐surface synthesis, respectively, their applications in electronics, remain less explored due to the challenges in thin‐film processability and device integration associated with the control of film thickness, layer orientation, stability and crystallinity. Moreover, although the crystalline domain sizes of the powder samples can reach micrometer scale (up to ≈1.5 μm), the reported thin‐film samples have so far rather small crystalline domains up to 100 nm. Here we demonstrate a general and efficient synthesis of crystalline two‐dimensional (2D) BECOF films composed of porphyrin macrocycles and phenyl or naphthyl linkers (named as 2D BECOF‐PP or 2D BECOF‐PN) by employing a surfactant‐monolayer‐assisted interfacial synthesis (SMAIS) on the water surface. The achieved 2D BECOF‐PP is featured as free‐standing thin film with large single‐crystalline domains up to ≈60 μm2 and tunable thickness from 6 to 16 nm. A hybrid memory device composed of 2D BECOF‐PP film on silicon nanowire‐based field‐effect transistor is demonstrated as a bio‐inspired system to mimic neuronal synapses, displaying a learning–erasing–forgetting memory process.

Nb 2 O 5 has been explored as a promising anode material for use as lithium-ion batteries (LIBs), but depending on the crystal structure, the specific capacity was always reported to be usually around or below 200 mAh/g. For the first time, we present coarse-grained Nb 2 O 5 materials that significantly overcome this capacity limitation with the promise of enabling high power applications. Our work introduces coarse-grained carbidederived Nb 2 O 5 phases obtained either by a one-step or a two-step bulk conversion process. By in situ production of chlorine gas from metal chloride salt at ambient pressure, we obtain in just one step directly orthorhombic Nb 2 O 5 alongside carbide-derived carbon (o-Nb 2 O 5 /CDC). In situ formation of chlorine gas from metal chloride salt under vacuum conditions yields CDC covering the remaining carbide core, which can be transformed into metal oxides covered by a carbon shell upon thermal treatment in CO 2 gas. The two-step process yielded a mixed-phase tetragonal and monoclinic Nb 2 O 5 with CDC (m-Nb 2 O 5 /CDC). Our combined diffraction and spectroscopic data confirm that carbide-derived Nb 2 O 5 materials show disordering of the crystallographic planes caused by oxygen deficiency in the structural units and, in the case of m-Nb 2 O 5 /CDC, severe stacking faults. This defect engineering allows access to a very high specific capacity exceeding the two-electron transfer process of conventional Nb 2 O 5 . The charge storage capacities of the resulting m-Nb 2 O 5 /CDC and o-Nb 2 O 5 /CDC are, in both cases, around 300 mAh/g at a specific current of 10 mA/g, thereby, the values are significantly higher than that of the state-of-the-art for Nb 2 O 5 as a LIB anode. Carbide-derived Nb 2 O 5 materials also show robust cycling stability over 500 cycles with capacity fading only 24% for the sample m-Nb 2 O 5 /CDC and 28% for o-Nb 2 O 5 /CDC, suggesting low degree of expansion/compaction during lithiation and delithiation.

Covalent organic frameworks (COFs) have garnered immense scientific interest among porous materials because of their structural tunability and diverse properties. However,the response of such materials towardlaser-induced nonlinear optical (NLO) applications is hardly understood and demands prompt attention. Three novel regioregular porphyrin (Por)-based porous COFs-Por-COF-HH and its dual metalated congeners Por-COF-ZnCu and Por-COF-ZnNi-have been prepared and present excellent NLO properties.N otably,i ntensity-dependent NLO switching behavior was observed for these Por-COFs,w hichi sh ighly desirable for optical switching and optical limiting devices. Moreover,t he efficient p-conjugation and charge-transfer transition in ZnCu-Por-COF enabled ahigh nonlinear absorption coefficient (b = 4470 cm/GW) and figure of merit (FOM = s 1 /s o ,3565) value compared to other state-of-the-art materials, including molecular porphyrins (b % 100-400 cm/GW), metalorganic frameworks (MOFs; b % 0.3-0.5 cm/GW), and graphene (b = 900 cm/GW). Molecules/materialswithinherentnonlinearoptical(NLO)properties have profound importance in telecommunications, data storage,d isplay technologies,s ensors,a nd biomedical devices. [1] In this regard, molecular porphyrins have been widely studied because of their versatile optical and electrochemical properties,large and fast NLO responses,possibility of incorporating aw ide range of metals,a nd their good thermochemical stabilities for optical limiting and optical switching applications. [2] Nonetheless,t oenhance and tune optical nonlinearities of singular porphyrin moieties,b athochromic shifting of their absorption bands by large p-electron delocalization is crucial, which becomes possible through de novo design of integrated porphyrin units featuring extended p-conjugation. [3, 4] Along this line,w ep ropose ap orphyrin-linked covalent organic framework (COF) [5] as model system, wherein enhancement and switching of the NLO response can be studied by manipulation of the framework. Among the recognized crystalline materials, COFs are known for being mechanically robust and offering ahighly accessible surface area. Thestructural and electronic tunability of COFs have garnered particular interest in research areas such as adsorption/storage, [6] chemical sensors, [7] electronics, [8] and catalysis. [9] Despite such potential, COFs comprising porphyrin units have not been explored as NLO materials.F or this purpose,aregioregular ordering of multiple metal centers in ac rystalline 2D porphyrin framework-preferably without ap ost-synthetic modification-is desirable.T his challenging objective [10] has great potential in optoelectronics and photo/electrocatalysis applications.Herein, we present aconjugated imine-linked porphyrinhomopolymeric COF (Por-COF-HH; Figure 1a)prepared by Schiff base A4B4 condensation of 5,10,15,20-tetrakis(4-formylphenyl)-21H,23H-porphyrin (TFPP) and 5,10,15,20-tetrakis(4-aminophenyl)-21H,23H-porphyrin (TAPP). Adopting the same pathway,w ea lso synthesized regioregular...