The practical utilization of covalent organic frameworks (COFs) with manipulation at the atomic and molecular scale often demands their assembly on the nano-, meso-, and macroscale with precise control. Consequently, synthetic approaches that establish the ability to control the nucleation and growth of COF crystallites and their self-assembly to desired COF nanomorphologies have drawn substantial attention from researchers. On the basis of the dimensionality of the COF morphologies, we can categorize them into zero- (0-D), one- (1-D), two- (2-D), and three-dimensional (3-D) nanomorphologies. In this perspective, we summarize the reported synthetic strategies that enable precise control of the COF nanomorphologies’ size, shape, and dimensionality and reveal the impact of the dimensionalities in their physicochemical properties and applications. The aim is to establish a synergistic optimization of the morphological dimensionality while keeping the micro- or mesoporosity, crystallinity, and chemical functionalities of the COFs in perspective. A detailed knowledge along the way should help us to enrich the performance of COFs in a variety of applications like catalysis, separation, sensing, drug delivery, energy storage, etc. We have discussed the interlinking between the COF nanomorphologies via the transmutation of the dimensionalities. Such dimensionality transmutation could lead to variation in their properties during the transition. Finally, the concept of constructing COF superstructures through the combination of two or more COF nanomorphologies has been explored, and it could bring up opportunities for developing next-generation innovative materials for multidisciplinary applications.

Synthesis of covalent organic framework (COF) thin films on different supports with high crystallinity and porosity is crucial for their potential applications. We have designed a new synchronized methodology, residual crystallization (RC), to synthesize sub 10 nm COF thin films. These residual crystallized COF thin films showcase high surface area, crystallinity, and conductivity at room temperature. We have used interfacial crystallization (IC) as a rate-controlling tool for simultaneous residual crystallization. We have also diversified the methodology of residual crystallization by utilizing two different crystallization pathways: fiber-to-film (F−F) and sphere-to-film (S−F). In both cases, we could obtain continuous COF thin films with high crystallinity and porosity grown on various substrates (the highest surface area of a TpAzo COF thin film being 2093 m 2 g −1 ). Precise control over the crystallization allows the synthesis of macroscopic defect-free sub 10 nm COF thin films with a minimum thickness of ∼1.8 nm. We have synthesized two COF thin films (TpAzo and TpDPP) using F−F and S−F pathways on different supports such as borosilicate glass, FTO, silicon, Cu, metal, and ITO. Also, we have investigated the mechanism of the growth of these thin films on various substrates with different wettability. Further, a hydrophilic support (glass) was used to grow the thin films in situ for four-probe system device fabrication. All residual crystallized COF thin films exhibit outstanding conductivity values. We could obtain a conductivity of 3.7 × 10 −2 mS cm −1 for the TpAzo film synthesized by S−F residual crystallization.

Peptide-based biomimetic catalysts are promising materials for efficient catalytic activity in various biochemical transformations. However, their lack of operational stability and fragile nature in non-aqueous media limit their practical applications. In this study, we have developed a cladding technique to stabilize biomimetic catalysts within porous covalent organic framework (COF) scaffolds. This methodology allows for the homogeneous distribution of peptide nanotubes inside the COF (TpAzo and TpDPP) backbone, creating strong noncovalent interactions that prevent leaching. We synthesized two different peptide-amphiphiles, C10FFVK and C10FFVR, with lysine (K) and arginine (R) at the C-termini, respectively, which formed nanotubular morphologies. The C10FFVK peptide-amphiphile nanotubes exhibit enzyme-like behavior and efficiently catalyze C–C bond cleavage in a buffer medium (pH 7.5). We produced nanotubular structures of TpAzo–C10FFVK and TpDPP–C10FFVK through COF cladding by using interfacial crystallization (IC). The peptide nanotubes encased in the COF catalyze C–C bond cleavage in a buffer medium as well as in different organic solvents (such as acetonitrile, acetone, and dichloromethane). The TpAzo–C10FFVK catalyst, being heterogeneous, is easily recoverable, enabling the reaction to be performed for multiple cycles. Additionally, the synthesis of TpAzo–C10FFVK thin films facilitates catalysis in flow. As control, we synthesized another peptide-amphiphile, C10FFVR, which also forms tubular assemblies. By depositing TpAzo COF crystallites on C10FFVR nanotubes through IC, we produced TpAzo–C10FFVR nanotubular structures that expectedly did not show catalysis, suggesting the critical role of the lysines in the TpAzo–C10FFVK.

Covalent organic frameworks (COFs) are ideal host matrices for biomolecule immobilization and biocatalysis due to their high porosity, various functionalities, and structural robustness. However, the porosity of COFs is limited...

The design and development of efficient and low-cost electrocatalysts for both anodic (oxygen evolution reaction (OER)/hydrazine oxidation reaction (HzOR)) and cathodic (hydrogen evolution reaction (HER)) reactions are the major challenges for cleaner hydrogen production. Especially, the fabrication of electrocatalysts with abundant electrochemically active sites through simple synthetic routes is of great interest to draw excellent catalytic efficiency. This report provides a strategy to prepare CoS2–MoS2 heterostructures and spheroid-like CoS2 through the sulfurization reaction from the common Co3O4 nanocube precursor in the presence and absence of the molybdenum precursor, respectively. The as-prepared CoS2–MoS2 (25) heterostructure (prepared with 25 mg of Co3O4) shows excellent HER activity in 1 M KOH by delivering a current density of 10 mA/cmgeo 2 at an overpotential of 92.5 ± 3.1 mV. The observed enhancement in the HER activity is attributed to the improved water dissociation kinetics at the abundant interfacial area shared between the two components of the heterostructure. Besides, spheroid-like CoS2 shows good OER and hydrazine oxidation reaction (HzOR) activity owing to the high electrochemically active surface area. In addition, the alkaline electrolyzer (HER//OER) constructed using the CoS2–MoS2 (25) heterostructure and spheroid-like CoS2 as the cathode and anode, respectively, delivers a current density of 10 mA/cmgeo 2 at a cell potential of 1.67 V. Furthermore, the hydrazine-assisted electrolyzer (HER//HzOR) displays a low cell potential of 0.53 V to attain the same current density along with excellent durability up to 30 h.

We report the development of iron-incorporated nickel sulfide (FeÀ Ni 3 S 4 /NiS 2 ) nanocomposite through sulfurization of iron incorporated nickel hydroxide precursor by using simple solvothermal method. The formation of Ni 3 S 4 / NiS 2 mixed-phase material was confirmed by PXRD analysis and the presence of multiple oxidation states of Ni (II and III) and incorporated Fe (III) was revealed by XPS studies. The electrochemical studies demonstrated that FeÀ Ni 3 S 4 /NiS 2 electrocatalyst has a high catalytic activity towards alkaline OER, as it requires only 280 mV overpotential to achieve the benchmark current density of 10 mA/cm 2 geo . The superiority of the catalyst was exhibited by low charge transfer resistance of about 6 Ohms, along with low Tafel slope of 43 mV dec À 1 . Further, the observed long-term stability for 72 h and remarkable Faradaic efficiency with 99% indicate good durability and excellent selectivity towards OER, respectively. The superior activity of FeÀ Ni 3 S 4 /NiS 2 is attributed to fast kinetics and low charge transfer resistance of the material facilitating the generation of active catalyst.

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