Polydopamine and Its Derivative Materials: Synthesis and Promising Applications in Energy, Environmental, and Biomedical Fields

Metal–organic frameworks (MOFs), also known as porous coordination polymers (PCPs), synthesized by assembling metal ions with organic ligands have recently emerged as a new class of crystalline porous materials. The amenability to design as well as fine-tunable and uniform pore structures makes them promising materials for a variety of applications. Controllable integration of MOFs and functional materials is leading to the creation of new multifunctional composites/hybrids, which exhibit new properties that are superior to those of the individual components through the collective behavior of the functional units. This is a rapidly developing interdisciplinary research area. This review provides an overview of the significant advances in the development of diverse MOF composites reported till now with special emphases on the synergistic effects and applications of the composites. The most widely used and successful strategies for composite synthesis are also presented.

Metal–organic framework composites

Rapidly increasing atmospheric CO2 concentrations threaten human society, the natural environment, and the synergy between the two. In order to ameliorate the CO2 problem, carbon capture and conversion techniques have been proposed. Metal–organic framework (MOF)-based materials, a relatively new class of porous materials with unique structural features, high surface areas, chemical tunability and stability, have been extensively studied with respect to their applicability to such techniques. Recently, it has become apparent that the CO2 capture capabilities of MOF-based materials significantly boost their potential toward CO2 conversion. Furthermore, MOF-based materials’ well-defined structures greatly facilitate the understanding of structure–property relationships and their roles in CO2 capture and conversion. In this review, we provide a comprehensive account of significant progress in the design and synthesis of MOF-based materials, including MOFs, MOF composites and MOF derivatives, and their application to carbon capture and conversion. Special emphases on the relationships between CO2 capture capacities of MOF-based materials and their catalytic CO2 conversion performances are discussed.

Carbon capture and conversion using metal–organic frameworks and MOF-based materials

Hierarchically porous carbons (HPCs) with 1D to 3D network are attracting vast interest due to their potential technological application profile ranging from electrochemical capacitors, lithium ion batteries, solar cells, hydrogen storage systems, photonic material, fuel cells, sorbent for toxic gas separation and so on. Natural raw-materials such as biomass-biopolymer derived hierarchical nanostructured carbons are especially attractive for their uniform pore dimensions which can be adjustable over a wide range of length scales. Good electrical conductivity, high surface area, and excellent chemical stability are unique physicochemical properties which are responsible for micro/nanostructured porous carbon to be highly trusted candidate for emerging nanotechnologies. This review focuses on the ‘out-of-the-box’ synthetic techniques capable of deriving HPC with superior application profiles. The article presents the promising scope of accessing HPCs from (1) hard-templating, soft-templating, and non-templating routes, (2) biopolymers with a major focus on non-templating strategies. Subsequently, emerging strategies of hetero-atom doping in porous carbon nanostructures are discussed. The review will highlight the contribution of synergistic effect of macro–meso–micropores on a range of emerging applications such as CO2 capture, carbon photonic crystal sensors, Li–S batteries, and supercapacitor. Mechanism of ion transport and buffering, electrical double layer enhancement have been discussed in the context of pore structure and shapes. We will also show the differences of HPC and ordered mesoporous carbon (OMC) in terms of their synthesis strategies and choices of template for self-assembly. How the remarkable mechanical strength of the HPCs can be achieved by selecting self-assembling template, whereas collapse of mesostructure via decomposition of framework occurs due to poor thermal stability or high N-content of the carbon source will be discussed.

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Hierarchically porous carbon derived from polymers and biomass: effect of interconnected pores on energy applications

https://iopscience.iop.org/article/10.1088/1468-6996/16/2/023501/pdf

Recent progress on magnetic iron oxide nanoparticles: synthesis, surface functional strategies and biomedical applications.

Dopamine is an excellent and flexible agent for surface coating of inorganic nanoparticles and contains unusually high concentrations of amine groups. In this study, we demonstrate that through a controlled coating of a thin layer of polydopamine on the surface of α-Fe(2)O(3) in the dopamine aqueous solution, followed by subsequent carbonization, N-doped carbon-encapsulated magnetite has been synthesized and shows excellent electrochemical performance as anode material for lithium-ion batteries. Due to the strong binding affinity to iron oxide and excellent coating capability of this new carbon precursor, the conformal polydopamine derived carbon is continuous and uniform, and its thickness can be tailored. Moreover, due to the high percentage of nitrogen content in the precursor, the resulting carbon layer contains a moderate amount of N species, which can substantially improve the electrochemical performance. The composites synthesized by this facile method exhibit superior electrochemical performance, including remarkably high specific capacity (>800 mA h g(-1) at a current of 500 mA g(-1)), high rate capability (595 and 396 mA h g(-1) at a current of 1000 and 2000 mA g(-1), respectively) and excellent cycle performance (200 cycles with 99% capacity retention), which adds to the potential as promising anodes for the application in lithium-ion batteries.

Dopamine as the coating agent and carbon precursor for the fabrication of N-doped carbon coated Fe3O4 composites as superior lithium ion anodes

Novel multifunctional composites composed of highly dispersed nanosized Fe2O3 particles, a tubular mesoporous carbon host, and a conductive polypyrrole (PPy) sealing layer are hierarchically assembled via two facile processes, including bottom-up introduction of Fe2O3 nanoparticles in tubular mesoporous carbons, followed by in situ surface sealing with the PPy coating. Fe2O3 particles are well-dispersed within the carbon matrix and PPy is spatially and selectively coated onto the external surface and the pore entrances of the Fe2O3@C composite, thereby bridging the composite particles together into a larger unit. As an anode material for Li-ion batteries (LIBs), the PPy-coated Fe2O3@C composite exhibits stable cycle performance. Additionally, the PPy-coated Fe2O3@C composite also possesses fast electrode reaction kinetics, high Fe2O3 use efficiency, and large volumetric capacity. The excellent electrochemical performance is associated with a synergistic effect of the highly porous carbon matrix and the conducting PPy sealing layer. Such multifunctional configuration prevents the aggregation of NPs and maintains the structural integrity of active materials, in addition to effectively enhancing the electronic conductivity and warranting the stability of as-formed solid electrolyte interface (SEI) films. This nanoengineering strategy might open new avenues for the design of other multifunctional composite architectures as electrode materials in order to achieve high-performance LIBs.

Nanoengineered Polypyrrole‐Coated Fe2O3@C Multifunctional Composites with an Improved Cycle Stability as Lithium‐Ion Anodes

Fe3O4 is a promising high-capacity anode material for lithium ion batteries, but challenges including short cycle life and low rate capability hinder its widespread implementation. In this work, a well-defined tubular structure constructed by carbon-coated Fe3O4 has been successfully fabricated with hierarchically porous structure, high surface area, and suitable thickness of carbon layer. Such purposely designed hybrid nanostructures have an enhanced electronic/ionic conductivity, stable electrode/electrolyte interface, and physical buffering effect arising from the nanoscale combination of carbon with Fe3O4, as well as the hollow, aligned and hierarchically porous architectures. When used as an anode material for a lithium-ion half cell, the carbon-coated hierarchical Fe3O4 nanotubes showed excellent cycling performance with a specific capacity of 1,020 mAh center dot g(-1) at 200 mA center dot g(-1) after 150 cycles, a capacity retention of ca. 103%. Even at a higher current density of 1,000 mA center dot g(-1), a capacity of 840 mAh center dot g(-1) is retained after 300 cycles with no capacity loss. In particular, a superior rate capability can be obtained with a stable capacity of 355 mAh center dot g(-1) at 8,000 mA center dot g(-1). The encouraging results indicate that hierarchically tubular hybrid nanostructures can have important implications for the development of high-rate electrodes for future rechargeable lithium ion batteries (LIBs).

http://www.thenanoresearch.com/upload/justPDF/0531.pdf

Rationally designed carbon-coated Fe3O4 coaxial nanotubes with hierarchical porosity as high-rate anodes for lithium ion batteries

This work aims to optimize the structural features of hierarchical porous carbon monolith (HCM) by incorporating the advantages of metal–organic frameworks (MOFs) (Cu3(BTC)2) to maximize the volumetric based CO2 capture capability (CO2 capacity in cm3 per cm3 adsorbent), which is seriously required for the practical application of CO2 capture. The monolithic HCM was used as a matrix, in which Cu3(BTC)2 was in situ synthesized, to form HCM-Cu3(BTC)2 composites by a step-by-step impregnation and crystallization method. The resulted HCM-Cu3(BTC)2 composites, which retain the monolithic shape and exhibit unique hybrid structure features of both HCM and Cu3(BTC)2, show high CO2 uptake of 22.7 cm3 cm–3 on a volumetric basis. This value is nearly as twice as the uptake of original HCM. The dynamic gas separation measurement of HCM-Cu3(BTC)2, using 16% (v/v) CO2 in N2 as feedstock, illustrates that CO2 can be easily separated from N2 under the ambient conditions and achieves a high separation factor for CO2 over ...

Synthesis of Hierarchical Porous Carbon Monoliths with Incorporated Metal–Organic Frameworks for Enhancing Volumetric Based CO2 Capture Capability

A new synthetic approach for the fabrication of microporous carbon materials (HCMs) by using discrete chelating zinc species as dynamic molecular porogens to create extra micropores that enhance their CO2-adsorption capacity and selectivity is reported. During the carbonization process, the evaporation of the in situ-formed Zn species would create additional nanochannels that contribute to the additional micropore volume for CO2 adsorption. The resultant HCMs show an increased number of micropores, with sizes in the range 0.7–1.0 nm and a high CO2-adsorption capacity of 5.4 mmol g � 1 (23.8 wt %) at 273 K and 3.8 mmol g � 1 (16.7 wt %) at 298 K and 1 bar, which are superior to those of most carbon-based adsorbents with Ndoping or high specific surface areas. Dynamic gas-separation measurements, by using 16 % CO2 in N2 (v/v) as a feedstock, demonstrated that CO2 could be effectively separated from N2 under ambient conditions and shows a high separation factor (SCO2/N2 = 110) for CO2 over N2, thereby reflecting a strongly competitive CO2-adsorption capacity. If the feedstock contained water vapor, the dynamic capacity of CO2 was almost identical to that measured under dry conditions, thus indicating that the carbon material had excellent tolerance to humidity. Easy CO2 release could be realized by purging an argon flow through the fixed-bed adsorber at 298 K, thus indicating good regeneration ability.

Cheng Lei

Papers

Dopamine as the coating agent and carbon precursor for the fabrication of N-doped carbon coated Fe3O4 composites as superior lithium ion anodes

Nanoengineered Polypyrrole‐Coated Fe2O3@C Multifunctional Composites with an Improved Cycle Stability as Lithium‐Ion Anodes

Rationally designed carbon-coated Fe3O4 coaxial nanotubes with hierarchical porosity as high-rate anodes for lithium ion batteries

Synthesis of Hierarchical Porous Carbon Monoliths with Incorporated Metal–Organic Frameworks for Enhancing Volumetric Based CO2 Capture Capability

A method for creating microporous carbon materials with excellent CO2-adsorption capacity and selectivity.