Thermal conversion of core-shell metal-organic frameworks: a new method for selectively functionalized nanoporous hybrid carbon.

New Strategies for Novel MOF-Derived Carbon Materials Based on Nanoarchitectures

Nano-porous carbon (NPCs) materials exhibit great application potential in industry because of its abundant pore structures, large specific surface area and easy to design. The key points of the research usually focus on the achievement of better performance and lower preparation cost through adjusting its composition and structure. Metal organic frameworks (MOFs) as a new kind of porous crystal material, have the outstanding features of adjustable composition, multiple structure, adjustable controllable pore size, which has received the widespread attention in catalysis, energy storage and conversion, gas storage, environmental restoration, and so on. In particular, based on the structure and composition of MOFs, it can be used for the preparation of various forms of porous carbon materials or a novel multifunctional carbon composite material as the common precursor. Compared with the composite material assembled with single component, the MOFs derived porous carbon materials often shows superior features. In this paper, the design principles and strategies for the preparation of porous carbon materials through MOFs pyrolysis are reviewed in this paper and the future development prospects and challenges are presented for obtain high performance porous carbon and its composite materials. MOFs derived porous carbon can be obtain via a pyrolysis process, which inherit the structure features of MOF precursor to a large extent. Researchers can design the MOFs derived porous carbon from the particle and pore size, heteroatom doping, metal species anchoring, microtopography and composite structure, etc., for expanding the application scope and improving performance. For the morphology, not only the zero dimensional quantum dot, two dimensional nanosheet and three dimensional framework can be prepared, but also NPCs can grow on different substrate surface to form a composite structure. Moreover, block or cloth integral NPCs materials also be reported to enrich the application form. For the composition, heteroatom doping such as N, S, P is proved to be effective approach to enhance the NPCs electro-catalytic property and the addition of secondary carbon source containing these atoms is a facile method to prepare such materials. More importantly, the metal species are evenly distributed in the MOFs as crosslinking sites, so the metal-loading NPCs can be easily obtained by direct carbonation, and the form of metal nanoparticle can be adjusted by controlling the precursor composition, pyrolysis conditions and post treatment. Especially, it is an inspiring and effective method to prepare uniform and high-loading single atom-immobilized NPCs based on MOFs structure. In order to promote the industrial application process of MOFs derived porous carbon materials, adopting cheaper ligands and developing simple synthesis and control methods are still the direction of efforts. Furthermore, it should strengthen the research of the inner relationship between special morphology, composition and application performance, and pay more attention to understand the action mechanism for the characteristics and formation of activity sites in the MOFs derived NPCs affecting its related application performance. Only by combining theoretical research and experimental analysis to guide the design of MOFs derived porous carbon materials in the future can we fabricate applicable NPCs material with both merits of low cost and excellent performance.

In recent years, nanoporous materials have attracted much attention owing to their high specific surface areas and narrow pore-size distribution. These materials have been widely used in gas storage, gas separation, catalysis and electrochemistry. Nanoporous carbon materials (NPCs), a sub-family of nanoporous materials, have been one type of the most popular functional materials. Enormous efforts have been made in the preparation of NPCs with various pore structures. Although many new NPCs have been prepared, most of them have mesoporous/macroporous/disordered structures, which limit their performance as functional materials. Therefore, the development of convenient synthetic methods to NPCs with narrower pore size at a microporous level is still a significant challenge. More recently, a novel, efficient synthetic method, thermal decomposition of metal-organic frameworks (MOFs), has been developed to obtain well-defined ordered NPCs with narrow pore sizes. MOFs have emerged as a new class of porous materials that are assembled with metal ions and organic ligands. Owing to their ordered structures, high surface areas, and large pore volumes, MOFs have been widely utilized in a variety of fields such as heterogeneous catalysis, electrochemistry, gas adsorption, and sensors. Considering the low coordination bond energy between the ligands and metal ions of MOFs, the stability of MOFs is normally lower than the traditional porous materials. MOFs have been considered as alternative precursors for the preparation of new metal oxides or carbon nanomaterials by pyrolysis. This article briefly reviews the recent progress in the preparation of these novel MOF-derived nanoporous carbons. We describe two methods to synthesize MOF-derived nanoporous carbons. One is one-step direct pyrolysis of MOFs for synthesis of nanoporous carbons. The other is introduced carbon sources into the micropores of MOFs before calcination. Furfuryl alcohol (FA), glycerol, carbon tetrachloride and ethylenediamine, and phenolic resin have been successfully employed as the carbon sources. In this review, MOFs-derived materials are classified to three species based on calcination atmosphere and metal ions, i.e., nanoporous carbons, metal/metal oxide nanoparticles embedded in a carbon matrix, and metal/metal oxide nanoparticles. At the same time, we also elaborate the applications of the porous carbon materials that are derived from MOFs as the sacrifice templates systematically. Some promising applications in, such as energy and environment-related areas, and the outlook of such types of materials are also discussed.

Single metal-organic frameworks (MOFs), constructed from the coordination between one-fold metal ions and organic linkers, show limited functionalities when used as precursors for nanoporous carbon materials. Herein, we propose to merge the advantages of zinc and cobalt metals ions into one single MOF crystal (i.e., bimetallic MOFs). The organic linkers that coordinate with cobalt ions tend to yield graphitic carbons after carbonization, unlike those bridging with zinc ions, due to the controlled catalytic graphitization by the cobalt nanoparticles. In this work, we demonstrate a feasible method to achieve nanoporous carbon materials with tailored properties, including specific surface area, pore size distribution, degree of graphitization, and content of heteroatoms. The bimetallic-MOF-derived nanoporous carbon are systematically characterized, highlighting the importance of precisely controlling the properties of the carbon materials. This can be done by finely tuning the components in the bimetallic MOF precursors, and thus designing optimal carbon materials for specific applications.

High surface area and large pore volume carbon materials having hierarchical nanoporous structure are required in high performance supercapacitors. Such nanoporous carbon materials can be fabricated from organic precursors with high carbon content, such as synthetic biomass or agricultural wastes containing cellulose, hemicellulose, and lignin. Using recently developed unique concept of materials nanoarchitectonics, high performance porous carbons with controllable surface area, pore size distribution, and hierarchy in nanoporous structure can be fabricated. In this review, we will overview the recent trends and advancements on the synthetic methods for the production of hierarchical porous carbons with one- to three-dimensional network structure with superior performance in supercapacitors applications. We highlight the promising scope of accessing nanoporous graphitic carbon materials from: (i) direct conversion of single crystalline self-assembled fullerene nanomaterials and metal organic frameworks, (ii) hard- and soft-templating routes, and (iii) the direct carbonization and/or activation of biomass or agricultural wastes as non-templating routes. We discuss the appealing points of the different synthetic carbon sources and natural precursor raw−materials derived nanoporous carbon materials in supercapacitors applications.

A novel approach for facile synthesis of cost-optimal catalyst for high-performance lithium-air battery

Nanoporous non-siliceous materials such as carbons, nitrides, and phosphides have attracted much attention in the recent years due to their enormous applications in the fields of adsorption, catalysis, and fuel cells. However, the incorporation of hetero atoms such as boron and nitrogen in the non-siliceous materials can significantly change their electronic and semi-conducting properties. Firstly I will present some results about the discovery of the nanoporous carbon and nitride materials, and the basics and the mechanism behind the synthesis of various nanoporous nitride materials with different pore structure and textural parameters. Then, the preparation, characterization and the applications of one and three dimensional nanoporous carbon nitrides materials synthesized using various inorganic templates with the different pore structures (MCN-1 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">1,2</sup> and MCN-2 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sup> ) through a simple polymerization reaction between ethylenediamine (EDA) and carbon tetrachloride (CTC) will be presented. Moreover, the methods to control the textural parameters and the nitrogen content of the nanoporous carbon nitride materials, which have been solely developed in my group, will also be discussed. <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">4</sup> Not only the powder materials but also the different ways for the fabrication of nanoporous carbon nitride nanoparticles and films with hierarchical ordered structure and morphology will be demonstrated. In addition, I will show some of the results on the preparation of nanoporous boron nitride (MBN) and boron carbon nitride (MBCN) which have been prepared by novel elemental substitution technique <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">5</sup> using nanoporous carbon as the template at very high temperature. In the last part of the talk, I briefly discuss about the different ways of preparing nanoporous carbon materials with various structure types, especially "Carbon Nanocage and Carbon Nanocoops", and to tune the pore diameters and textural parameters. The applications of the materials including sensing of different molecules and biosensing will be discussed in detail. <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">6−12</sup>

Ultrahigh-content nitrogen-decorated nanoporous carbon derived from metal organic frameworks and its application in supercapacitors

Nanoporous carbon and nanoporous cobalt oxide (Co3O4) materials have been selectively prepared from a single metal-organic framework (MOF) (zeolitic imidazolate framework, ZIF-67) by optimizing the annealing conditions. The resulting ZIF-derived carbon possesses highly graphitic walls and a high specific surface area of 350 m(2)·g(-1), while the resulting ZIF-derived nanoporous Co3O4 possesses a high specific surface area of 148 m(2)·g(-1) with much less carbon content (1.7 at%). When nanoporous carbon and nanoporous Co3O4 were tested as electrode materials for supercapacitor application, they showed high capacitance values (272 and 504 F·g(-1), respectively, at a scan rate of 5 mV·s(-1)). To further demonstrate the advantages of our ZIF-derived nanoporous materials, symmetric (SSCs) and asymmetric supercapacitors (ASCs) were also fabricated using nanoporous carbon and nanoporous Co3O4 electrodes. Improved capacitance performance was successfully realized for the ASC (Co3O4//carbon), better than those of the SSCs based on nanoporous carbon and nanoporous Co3O4 materials (i.e., carbon//carbon and Co3O4//Co3O4). The developed ASC with an optimal mass loading can be operated within a wide potential window of 0.0-1.6 V, which leads to a high specific energy of 36 W·h·kg(-1). More interestingly, this ASC also exhibits excellent rate capability (with the highest specific power of 8000 W·kg(-1) at a specific energy of 15 W·h·kg(-1)) combined with long-term stability up to 2000 cycles.

2H-MoS ₂ Modified Nitrogen-Doped Hollow Mesoporous Carbon Spheres as the Efficient Catalytic Cathode Catalyst for Aprotic Lithium-Oxygen Batteries

Nanoporous carbon materials are highly important materials for a wide array of applications. Here we show that nanoporous carbon can act as highly active materials for electrochemical sensing. We observed that nanoporous carbon material exhibits a faster heterogeneous electron transfer than graphite and pure carbon nanotubes. Nanoporous carbon exhibits a superior electrochemical performance for sensing of important biomarkers such as dopamine, ascorbic acid, uric acid, NADH, DNA bases, and forensic-related compounds such as nitroaromatic explosives.

A simple Mg(OH)2-assisted template carbonization method to N-doped nanoporous carbon material from phenidone and the capacitive improvement with the addition of azobisformamide

Here we demonstrate a facile approach to grow uniform and large area single layer graphene directly over polycrystalline metal foil from nanoporous carbon (NC) material. The NC is synthesized by using the adamantane (C10H16) flame method. The flame-annealing of adamantane resulted in the conversion of adamantane to NC. The size of NC is ∼80 to 100 nm. The prepared sandwich structures (Mo–NC–Ni–dielectric–Mo) were annealed at 850 to 950 °C, where NC was used as a carbon source material. The NC material was successfully transformed into single layer graphene. We have explored the possibility of using our approach to grow graphene in low vacuum (1 × 10−10 Pa) air instead of inert Ar atmosphere. The generated pressure on sandwich structures has enhanced the density/scalability as well as the quality of graphene. We observed the sheet resistance of graphene was ∼929 Ω per sq at 91.8% transparency. Our work expands the possibility of synthesizing single-layer graphene from various carbon source materials. Moreover, the synthesized graphene films can be applied for future electronics applications.

Nanoporous activated carbon materials derived from agro-wastes could be suitable low-cost electrode materials for high-rate performance electrochemical supercapacitors. Here we report high surface area nanoporous carbon materials derived from Lapsi seed agro-waste prepared by zinc chloride (ZnCl2) activation at 700 °C. Powder X-ray diffraction (pXRD) and Raman scattering confirmed the amorphous structure of the resulting carboniferous materials, which also incorporate oxygen-containing functional groups as confirmed by Fourier transform infrared (FTIR) spectroscopy. Scanning and transmission electron microscopy (SEM and TEM) analyses revealed the granular, nanoporous structures of the materials. High-resolution TEM (HR-TEM) confirmed a graphitic carbon structure containing interconnected mesopores. Surface areas and pore volumes of the materials were found, respectively, in the ranges from 931 to 2272 m2 g−1 and 0.998 to 2.845 cm3 g−1, and are thus superior to commercially available activated carbons. High surface areas, large pore volumes and interconnected mesopore structures of these Lapsi seed-derived nanoporous carbon materials lead to their excellent electrochemical supercapacitance performance in aqueous electrolyte (1 M H2SO4) with a maximum specific capacitance of 284 F g−1 at a current density of 1 A g−1. Furthermore, the electrodes showed high-rate capability sustaining 67.7% capacity retention even at high current density of 20 A g−1 with excellent cycle stability achieving 99% capacitance retention even after 10,000 charge–discharge cycles demonstrating the potential of Lapsi seed derived nanoporous carbons as suitable electrode materials in high-performance supercapacitor devices.

Nanoporous carbons derived from metal-conjugated phosphoprotein/silica: Efficient electrocatalysts for oxygen reduction and hydrazine oxidation reactions