One of the key challenges in two-dimensional (2D) materials is to go beyond graphene, a prototype 2D polymer (2DP), and to synthesize its organic analogues with structural control at the atomic- or molecular-level. Here we show the successful preparation of porphyrin-containing monolayer and multilayer 2DPs through Schiff-base polycondensation reaction at an air–water and liquid–liquid interface, respectively. Both the monolayer and multilayer 2DPs have crystalline structures as indicated by selected area electron diffraction. The monolayer 2DP has a thickness of∼0.7 nm with a lateral size of 4-inch wafer, and it has a Young's modulus of 267±30 GPa. Notably, the monolayer 2DP functions as an active semiconducting layer in a thin film transistor, while the multilayer 2DP from cobalt-porphyrin monomer efficiently catalyses hydrogen generation from water. This work presents an advance in the synthesis of novel 2D materials for electronics and energy-related applications.

Despite rapid progress in recent years, it has remained challenging to prepare crystalline twodimensional polymers. Here, we report the controlled synthesis of few-layer 2D polyimide crystals on the water surface, through reaction between amine and anhydride monomers, assisted by surfactant monolayers. We obtained 2D polymers with high crystallinity, a thickness of approximately 2 nm, and an average crystal domain size of around 3.5 μm 2. The molecular structure of the materials, their grain boundaries, and their edge structures were characterized using X-ray scattering and transmission electron microscopy techniques, and supported by computations. The formation of crystalline polymers is attributed to the preorganization of monomers at the water-surfactant interface. Depending on its polar head, the surfactant promoted the arrangement of the monomers-and in turn their polymerizationeither horizontally or vertically with respect to the water surface. The latter was observed with a surfactant bearing a carboxylic acid group, which anchored amine monomers vertically through a condensation reaction. In both instances, micrometre-sized 2D polyamide crystals were grown.

Engineering conducting polymer thin films with morphological homogeneity and long-range molecular ordering is intriguing to achieve high-performance organic electronics. Polyaniline (PANI) has attracted considerable interest due to its appealing electrical conductivity and diverse chemistry. However, the synthesis of large-area PANI thin film and the control of its crystallinity and thickness remain challenging because of the complex intermolecular interactions of aniline oligomers. Here we report a facile route combining air-water interface and surfactant monolayer as templates to synthesize crystalline quasi-two-dimensional (q2D) PANI with lateral size ~50 cm2 and tunable thickness (2.6–30 nm). The achieved q2D PANI exhibits anisotropic charge transport and a lateral conductivity up to 160 S cm−1 doped by hydrogen chloride (HCl). Moreover, the q2D PANI displays superior chemiresistive sensing toward ammonia (30 ppb), and volatile organic compounds (10 ppm). Our work highlights the q2D PANI as promising electroactive materials for thin-film organic electronics.

Nanoporous graphene and related atomically thin layered materials are promising candidates in reverse electrodialysis research owing to their remarkable ionic conductivity and high permselectivity. The synthesis of atomically thin nanoporous membranes with a narrow pore size distribution, however, remains challenging. Here, we report the fabrication of nanoporous carbon membranes via the thermal crosslinking of core-rim structured monomers, that is, polycyclic aromatic hydrocarbons. The mechanically robust, centimetre-sized membrane has a pore size of 3.6 ± 1.8 nm and a thickness of 2.0 ± 0.5 nm. When applied to reverse electrodialysis, the nanoporous carbon membrane offers a high short-circuit current with an output power density of 67 W m −2 , which is about two orders of magnitude beyond that of the classic ion-exchange membranes and current prototype nanoporous membranes reported in the literature. Crosslinked and atomically thin porous polycyclic aromatic hydrocarbon membranes therefore represent new scaffolds that will revolutionize the rapidly developing fields of sustainable energy and membrane technology.

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.

Two-dimensional conjugated metal-organic frameworks (2D c-MOFs) have recently emerged for potential applications in (opto-)electronics, chemiresistive sensing, and energy storage and conversion, due to their excellent electrical conductivity, abundant active sites, and intrinsic porous structures. However, developing ultrathin 2D c-MOF nanosheets (NSs) for facile solution processing and integration into devices remains a great challenge, mostly due to unscalable synthesis, low yield, limited lateral size and low crystallinity.Here, we report a surfactant-assisted solution synthesis toward ultrathin 2D c-MOF NSs, including HHB- Cu(HHB ¼ hexahydroxybenzene), HHB-Ni and HHTP-Cu (HHTP ¼ 2,3,6,7,10,11hexahydroxytriphenylene). For the first time, we achieve single-crystalline HHB-Cu(Ni) NSs featured with a thickness of 4-5 nm ($8-10 layers) and a lateral size of 0.25-0.65 mm 2 , as well as single-crystalline HHTP-Cu NSs with a thickness of $5.1 AE 2.6 nm ($10 layers) and a lateral size of 0.002-0.02 mm 2 . Benefiting from the ultrathin feature, the synthetic NSs allow fast ion diffusion and high utilization of active sites. As a proof of concept, when serving as a cathode material for Li-ion storage, HHB-Cu NSs deliver a remarkable rate capability (charge within 3 min) and long-term cycling stability (90% capacity retention after 1000 cycles), superior to the corresponding bulk materials and other reported MOF cathodes.

Single‐layer and multi‐layer 2D polyimine films have been achieved through interfacial synthesis methods. However, it remains a great challenge to achieve the maximum degree of crystallinity in the 2D polyimines, which largely limits the long‐range transport properties. Here we employ a surfactant‐monolayer‐assisted interfacial synthesis (SMAIS) method for the successful preparation of porphyrin and triazine containing polyimine‐based 2D polymer (PI‐2DP) films with square and hexagonal lattices, respectively. The synthetic PI‐2DP films are featured with polycrystalline multilayers with tunable thickness from 6 to 200 nm and large crystalline domains (100–150 nm in size). Intrigued by high crystallinity and the presence of electroactive porphyrin moieties, the optoelectronic properties of PI‐2DP are investigated by time‐resolved terahertz spectroscopy. Typically, the porphyrin‐based PI‐2DP 1 film exhibits a p‐type semiconductor behavior with a band gap of 1.38 eV and hole mobility as high as 0.01 cm2 V−1 s−1, superior to the previously reported polyimine based materials.

Insufficient catalytic activity and stability and high cost are the barriers for Pt‐based electrocatalysts in wide practical applications. Herein, a hierarchically porous PtNi nanoframe/N‐doped graphene aerogel (PtNiNF‐NGA) electrocatalyst with outstanding performance toward methanol oxidation reaction (MOR) in acid electrolyte has been developed via facile tert‐butanol‐assisted structure reconfiguration. The ensemble of high‐alloying‐degree‐modulated electronic structure and correspondingly the optimum MOR reaction pathway, the structure superiorities of hierarchical porosity, thin edges, Pt‐rich corners, and the anchoring effect of the NGA, endow the PtNiNF‐NGA with both prominent electrocatalytic activity and stability. The mass and specific activity (1647 mA mgPt−1, 3.8 mA cm−2) of the PtNiNF‐NGA are 5.8 and 7.8 times higher than those of commercial Pt/C. It exhibits exceptional stability under a 5‐hour chronoamperometry test and 2200‐cycle cyclic voltammetry scanning.