Polysaccharide‐Derived Carbons for Polar Analyte Separations

Highly mesoporous (Brunauer–Emmett–Teller surface area, S_BET > 200 m² g^?1; mesopore volume > 1 cm³ g^?1) carbonaceous materials are prepared in a truly sustainable manner, from the naturally occurring polysaccharide alginic acid. This approach yields large mesoporous materials (pore diameter > 14 nm) significantly without the use of a template or carbonization catalyst. The direct thermal decomposition of mesoporous forms of the acidic polysaccharide allows for an extremely flexible material preparation strategy. Materials can be prepared at any desired carbonization temperature (e.g., 200–1000 °C), possessing similar textural properties, but progressively presenting more uniform surface functionality through this temperature range, from more oxygenated surfaces at low temperatures to increasingly aromatic/graphitic‐like surfaces. The high‐temperature material (i.e., 1000 °C), while predominantly amorphous, presents some short range (turbostratic) ordering, providing sufficiently polarizable surfaces on which to perform challenging liquid phase separations of polar sugar analytes.     

Synthesis and Application of Graphitic Carbon with High Surface Area

Nanostructured graphitic carbons have widespread applications. However, the synthesis of such materials with a high surface area is still a great challenge. In this study, we demonstrate a new approach for improving the surface area. Graphitic carbon nanocages (CNCs) are prepared by spray pyrolysis of ethanol with dissolved iron carbonyl at high temperature. Ammonium thiocyanate is added to form iron sulfide as a less active catalyst and a template with less carbon dissolution and precipitation than single‐phase Fe. This addition leads to an apparent reduction in cage size from 60 to 40 nm and wall thickness from 5–10 nm to 2–4 nm and a significant increase in surface area from 227 to 550 m² g^?1 at 800 °C. As an example of a potential application, the CNCs with a thin wall and high surface area are demonstrated to be a superb material for supporting the Pt catalyst used in low‐temperature fuel cells. It is suggested that the present approach may be integrated with previous methods for improving the surface area of graphitic carbons and their performance in many areas of interest.     

Porous Carbons: Structure‐Oriented Design and Versatile Applications

Porous carbon materials have demonstrated exceptional performance in a variety of energy‐ and environment‐related applications. Over the past decades, tremendous efforts have been made in the coordinated design and fabrication of porous carbon nanoarchitectures in terms of pore sizes, surface chemistry, and structure. Herein, structure‐oriented carbon design and applications are reviewed. The unique properties of porous carbon materials that offer them promising design opportunities and broad applicability in some representative fields, including water remediation, CO₂ capture, lithium‐ion batteries, lithium–sulfur batteries, lithium metal anodes, Na‐ion batteries, K‐ion batteries, supercapacitors, and the oxygen reduction reaction are highlighted. Then, the most up‐to‐date strategies for structural control and functionalization of porous carbons are summarized, toward tailoring microporous, mesoporous, macroporous, and hierarchically porous carbons with disordered or ordered, amorphous or graphitic structures. Meanwhile, the emerging features of these structures in various applications are introduced where applicable. Finally, insights into the challenges and perspectives for future development are provided.     

Direct Heating Amino Acids with Silica: A Universal Solvent‐Free Assembly Approach to Highly Nitrogen‐Doped Mesoporous Carbon Materials

A general solvent‐free assembly approach via directly heating amino acid and mesoporous silica mixtures is developed for the synthesis of a family of highly nitrogen‐doped mesoporous carbons. Amino acids have been used as the sole precursors for templating synthesis of a series of ordered mesoporous carbons. During heating, amino acids are melted and strongly interact with silica, leading to effective loading and improved carbon yields (up to ≈25 wt%), thus to successful structure replication and nitrogen‐doping. Unique solvent‐free structure assembly mechanisms are proposed and elucidated semi‐quantitatively by using two affinity scales. Significantly high nitrogen‐doping levels are achieved, up to 9.4 (16.0) wt% via carbonization at 900 (700) °C. The diverse types of amino acids, their variable interactions with silica and different pyrolytic behaviors lead to nitrogen‐doped mesoporous carbons with tunable surface areas (700–1400 m² g^?1), pore volumes (0.9–2.5 cm³ g^?1), pore sizes (4.3–10 nm), and particle sizes from a single template. As demonstrations, the typical nitrogen‐doped carbons show good performance in CO₂ capture with high CO₂/N₂ selectivities up to ≈48. Moreover, they show attractive performance for oxygen reduction reaction, with an onset and a half‐wave potential of ≈?0.06 and ?0.14 V (vs Ag/AgCl).     

N‐Doped Polypyrrole‐Based Porous Carbons for CO2 Capture

Highly porous N‐doped carbons have been successfully prepared by using KOH as activating agent and polypyrrole (PPy) as carbon precursor. These materials were investigated as sorbents for CO₂ capture. The activation process was carried out under severe (KOH/PPy = 4) or mild (KOH/PPy = 2) activation conditions at different temperatures in the 600–800 °C range. Mildly activated carbons have two important characteristics: i) they contain a large number of nitrogen functional groups (up to 10.1 wt% N) identified as pyridonic‐N with a small proportion of pyridinic‐N groups, and ii) they exhibit, in relation to the carbons prepared with KOH/PPy = 4, narrower micropore sizes. The combination of both of these properties explains the large CO₂ adsorption capacities of mildly activated carbon. In particular, a very high CO₂ adsorption uptake of 6.2 mmol·g^?1 (0 °C) was achieved for porous carbons prepared with KOH/PPy = 2 and 600 °C (1700 m²·g^?1, pore size ≈ 1 nm and 10.1 wt% N). Furthermore, we observed that these porous carbons exhibit high CO₂ adsorption rates, a good selectivity for CO₂‐N₂ separation and it can be easily regenerated.     

Oxidation‐Resistant and Elastic Mesoporous Carbon with Single‐Layer Graphene Walls

An oxidation‐resistant and elastic mesoporous carbon, graphene mesosponge (GMS), is prepared. GMS has a sponge‐like mesoporous framework (mean pore size is 5.8 nm) consisting mostly of single‐layer graphene walls, which realizes a high electric conductivity and a large surface area (1940 m² g^?1). Moreover, the graphene‐based framework includes only a very small amount of edge sites, thereby achieving much higher stability against oxidation than conventional porous carbons such as carbon blacks and activated carbons. Thus, GMS can simultaneously possess seemingly incompatible properties; the advantages of graphitized carbon materials (high conductivity and high oxidation resistance) and porous carbons (large surface area). These unique features allow GMS to exhibit a sufficient capacitance (125 F g^?1), wide potential window (4 V), and good rate capability as an electrode material for electric double‐layer capacitors utilizing an organic electrolyte. Hence, GMS achieves a high energy density of 59.3 Wh kg^?1 (material mass base), which is more than twice that of commercial materials. Moreover, the continuous graphene framework makes GMS mechanically tough and extremely elastic, and its mean pore size (5.8 nm) can be reversibly compressed down to 0.7 nm by simply applying mechanical force. The sponge‐like elastic property enables an advanced force‐induced adsorption control.     

High‐Surface‐Area Nanoporous Boron Carbon Nitrides for Hydrogen Storage

Nano‐ and mesoporous boron carbon nitrides with very high surface areas up to 1560 m² g^?1 are obtained by pyrolysis of a graphitic carbon nitride mpg‐C₃N₄ infiltrated with a borane complex. This reactive hard‐templating approach provides easy composition and texture tuning by temperature adjustment between 800 and 1400 °C. The process yields B_xC_yN_zO_vH_w materials as direct copies of the initial template with controlled compositions of 0.15 ≤ x ≤ 0.36, 0.10 ≤ y ≤ 0.12, 0.14 ≤ z ≤ 0.32, and 0.11 ≤ v ≤ 0.28. The nano and mesoporosities can also be tuned in order to provide hierarchical materials with specific surface areas ranging from 610 to 1560 m² g^?1. Such high values, coupled with resistance against air oxidation up to 700 °C, suggest potential materials for gas storage and as catalyst supports. Indeed, it is demonstrated that these compounds exhibit high and tunable H₂ uptakes from 0.55 to 1.07 wt.% at 77 K and 1 bar, thus guiding further search of materials for hydrogen storage.     

“Brain‐Coral‐Like” Mesoporous Hollow CoS2@N‐Doped Graphitic Carbon Nanoshells as Efficient Sulfur Reservoirs for Lithium–Sulfur Batteries

Hollow carbon materials are considered promising sulfur reservoirs for lithium–sulfur batteries owing to their internal void space and porous conductive shell, providing high loading and utilization of sulfur. Since the pores in carbon materials play a critical role in the infusion of sulfur, access of the electrolyte, and the passage of lithium polysulfides (LPSs), the creation and tuning of hierarchical pore structures is strongly required to improve the electrochemical properties of sulfur/porous carbon composites, but remains a major challenge. Herein, a “brain‐coral‐like” mesoporous hollow carbon nanostructure consisting of an in situ‐grown N‐doped graphitic carbon nanoshell (NGCNs) matrix and embedded CoS₂ nanoparticles as an efficient sulfur host is presented. The rational synthetic design based on metal–organic framework chemistry furnishes unusual multiple porosity in a carbon scaffold with a macrohollow in the core and microhollows and mesopores in the shell, without the use of any surfactant or template. The CoS₂@NGCNs/S composite electrode facilitates high sulfur loading (75 wt%), strong adsorption of LPSs, efficient reaction kinetics, and stable cycle performance (903 mAh g^?1 at 0.1 C after 100 cycles), derived from the synergetic effects of the dual hollow features, chemically active CoS₂, and the conductive and mesoporous N‐doped carbon matrix.     

Sulfur‐Functionalized Mesoporous Carbon

A simple synthesis route to mesoporous carbons that contain heteroaromatic functionality is described. The sulfur‐functionalized mesoporous carbon (S‐FMC) materials that have been prepared show excellent thermal stability, as well as excellent hydrothermal stability, and stability over a wide range of pH values. These materials also show excellent mercury sorption performance over a broad range of pH, much broader than is possible with thiol‐based functionality or most silica‐based sorbents. The superior performance of these mesoporous heterocarbons as heavy‐metal sorbent material is demonstrated. These materials are shown to be stable at elevated temperatures and extreme pHs, making them ideally suited as a new class of absorbent material.     

Heteroatom (N or N‐S)‐Doping Induced Layered and Honeycomb Microstructures of Porous Carbons for CO2 Capture and Energy Applications

Increasing global challenges such as climate change, environmental pollution, and energy shortage have stimulated the worldwide explorations into novel and clean materials for their applications in the capture of carbon dioxide, a major greenhouse gas, and toxic pollutants, energy conversion, and storage. In this study, two microstructured carbons, namely N‐doped pillaring layered carbon (NC) and N, S codoped honeycomb carbon (NSC), have been fabricated through a one‐pot pyrolysis process of a mixture containing glucose, sodium bicarbonate, and urea or thiourea. The heteroatom doping is found to induce tailored microstructures featuring highly interconnected pore frameworks, high sp²‐C ratios, and high surface areas. The formation mechanism of the varying pore frameworks is believed to be hydrogen‐bond interactions. NSC displays a similar CO₂ adsorption capacity (4.7 mmol g^?1 at 0 °C), a better CO₂/N₂ selectivity, and higher activity in oxygen reduction reaction as compared with NC‐3 (the NC sample with the highest N content of 7.3%). NSC favors an efficient four‐electron reduction pathway and presents better methanol tolerance than Pt/C in alkaline media. The porous carbons also exhibit excellent rate performance as supercapacitors.     

Template‐Free Fabrication and Enhanced Photocatalytic Activity of Hierarchical Macro‐/Mesoporous Titania

Hierarchical macro‐/mesoporous titania is prepared without the addition of templates or auxiliary additives at room temperature by the simple dropwise addition of tetrabutyl titanate to pure water, and then calcined at various temperatures. The products are characterized by X‐ray diffraction, N₂‐adsorption–desorption analysis, scanning electron microscopy, and the corresponding photocatalytic activity is evaluated by measuring the photocatalytic oxidation of acetone in air. The results reveal that hierarchical macro‐/mesoporous structures of titania can spontaneously form by self‐assembly in alkoxide–water solutions in the absence of organic templates or auxiliary additives. The calcination temperature has a strong effect on the structures and photocatalytic activity of the prepared titania. At 300 °C, the calcined sample shows the highest photocatalytic activity. At 400 and 500 °C, the photocatalytic activity slightly decreases. When the calcination temperature is higher than 500 °C, the photocatalytic activity greatly decreases because of the destruction of the hierarchical macro‐/mesoporous structure of the titania and the drastic decrease of specific surface area. The hierarchically macro‐/mesostructured titania network with open and accessible pores is well‐preserved after calcination at 500 °C, indicating especially high thermal stability. The macroporous channel structures are even preserved after calcination at 800 °C. This hierarchical macro‐/mesostructured titania is significant because of its potential applications in photocatalysis, catalysis, solar‐cell, separation, and purification processes.     

Block‐Copolymer‐Templated Synthesis of Electroactive RuO2‐Based Mesoporous Thin Films

RuO₂‐based mesoporous thin films of optical quality are synthesized from ruthenium‐peroxo‐based sols using micelle templates made of amphiphilic polystyrene‐polyethylene oxide block copolymers. The mesoporous structure and physical properties of the RuO₂ films (mesoporous volume: 30%; pore diameter: ～30 nm) can be controlled by the careful tuning of both the precursor solution and thermal treatment (150–350 °C). The optimal temperature that allows control of both mesoporosity and nanocristallinity is strongly dependent on the substrate (silicon or fluorine‐doped tin oxide). The structure of the resulting mesoporous films are investigated using X‐ray diffraction, X‐ray photoelectron spectroscopy, and atomic force microscopy. Mesoporous layers are additionally characterized by transmission and scanning electron microscopy and ellipsometry while their electrochemical properties are analyzed via cyclic voltammetry. Thick mesoporous films of ruthenium oxide hydrates, RuO₂ · xH₂O, obtained using a thermal treatment at 280 °C, exhibit capacitances as high as 1000 ± 100 F g^?1 at a scan rate of 10 mV s^?1, indicating their potential application as electrode materials.     

Block‐Copolymer‐Assisted One‐Pot Synthesis of Ordered Mesoporous WO3−x/Carbon Nanocomposites as High‐Rate‐Performance Electrodes for Pseudocapacitors

An ordered mesoporous tungsten‐oxide/carbon (denoted as m‐WO_3?x‐C‐s) nanocomposite is synthesized using a simple one‐pot method using polystyrene‐block‐poly(ethylene oxide) (PS‐b‐PEO) as a structure‐directing agent. The hydrophilic PEO block interacts with the carbon and tungsten precursors (resol polymer and WCl₆), and the PS block is converted to pores after heating at 700 °C under a nitrogen flow. The m‐WO_3?x‐C‐s nanocomposite has a high Brunauer–Emmett–Teller (BET) surface area and hexagonally ordered pores. Because of its mesoporous structure and high intrinsic density of tungsten oxide, this material exhibits a high average volumetric capacitance and gravimetric capacitance as a pseudocapacitor electrode. In comparison with reduced mesoporous tungsten oxide (denoted as m‐WO_3?x‐h), which is synthesized by a tedious hard template approach and further reduction in a H₂/N₂ atmosphere, m‐WO_3?x‐C‐s shows a high capacitance and enhanced rate performance, as confirmed by cyclic voltammetry, galvanostatic charge/discharge measurements, and electrochemical impedance spectroscopy. The good performance of m‐WO_3?x‐C‐s is attributed to the high surface area arising from the mesoporous structure, the large interconnected mesopores, and the low internal resistance from the well‐dispersed reduced tungsten oxide and amorphous carbon composite structure. Here, the amorphous carbon acts as an electrical pathway for effective pseudocapacitor behavior of WO_3‐x.     

Preparation of Highly Ordered Nitrogen‐Containing Mesoporous Carbon from a Gelatin Biomolecule and its Excellent Sensing of Acetic Acid

Novel nitrogen‐containing mesoporous carbon with well‐ordered pores (NMC‐G) and high basicity is synthesized using a low‐cost single‐molecule precursor, gelatin biomolecule, and SBA‐15 as a template via nanocasting method. The obtained materials are thoroughly characterized. It is found that the prepared materials have excellent textural properties such as high specific surface areas, huge pore volumes, and large pore diameters. The pore diameter of the materials can also be controlled with a simple adjustment of the pore diameter of the hard templates. The C/N ratio of the samples is calculated to be ≈6.01, which is slightly higher than that observed for mesoporous carbon nitride samples. X‐ray photoelectron spectroscopy (XPS) reveals the presence of sp² hybridized carbon in aromatic ring structure attached to amino groups. The materials could adsorb a huge quantity of CO₂. The sensing capability of the materials with different pore diameters for different adsorbates including ethanol, acetic acid, aniline, toluene, and ammonia is also investigated. Among the materials with different pore diameters studied, the material with the highest basicity and the largest pore diameter (NMC‐G‐150) showed excellent sensing performance with a high selectivity of adsorption for acetic acid molecule.     

Bottom‐Up Preparation of Fully sp2‐Bonded Porous Carbons with High Photoactivities

Porous carbons, possessing exceptional stability, high surface area, and electric conductivity, are broadly used as superior adsorbent, supporter, or electrode material for environmental protection, industrial catalysis, and energy storage and conversion. The construction of such kinds of materials with designable structures and properties will extremely extend their potential applications, but remains a huge synthetic challenge. Herein, a bottom‐up approach is presented to synthesize one type of fully sp² carbon–bonded frameworks by transition metal–catalyzed cross‐coupling of different polyphenylenes with electron‐withdrawing 9,9′‐bifluorenylidene (9,9′‐BF) through its 2,7‐position. The resulting porous polymeric carbons exhibit substantial semiconducting properties, such as strong light‐harvesting capabilities in the visible light region, likely due to their π‐extended backbones with donor–acceptor characters. Their electronic and porous structures can be finely tuned via the polyphenylene spacers. The intriguing properties allow these porous carbons to efficiently catalyze dye degradation under visible light or even natural sunlight with high reusability. Meanwhile, associated with their intrinsic structures, these porous carbons also exhibit highly selective degradation activities toward different dyes. In particular, the photodegradation mechanism involving oxygen and electron is elucidated for the first time for such kinds of materials, related to the presence of specific 9,9′‐BF units in their π‐conjugated skeletons.     

Unprecedentedly Tough,Folding‐Endurance,and Multifunctional Graphene‐Based Artificial Nacre with Predesigned 3D Nanofiber Network as Matrix

Mimicking the hierarchical brick‐and‐mortar architecture of natural nacre provides great opportunities for the design and synthesis of multifunctional artificial materials. The crucial challenge to push nacre‐mimetic functional materials toward practical applications is to achieve ample ductility, toughness, and folding endurance with simultaneously maintaining high‐level functional properties. In this study, the microstructure of nacre‐mimetics is reformed through predesigning a 3D nanofiber network to replace conventional polymer matrices. A unique sol–gel–film transformation approach is developed to fabricate a graphene‐based artificial nacre containing a preforming 3D, interconnective, inhomogeneous poly(p‐phenylene benzobisoxazole) nanofiber network. The fabulous coupling of the extensive sliding of graphene nanoplatelets and intensive stretching of the 3D nanofiber network over a large scale enables the artificial nacre to display natural nacre‐like deformation behavior, achieving ultralarge strain‐to‐failure (close to 35%), unprecedented toughness (close to 50 MJ m^?3), and fold endurance (no decrease in tensile properties after folding for 10 000 times or folding at increasing stress). The new levels of ductility, toughness, and folding endurance are integrated with outstanding thermal properties, including thermal conductivity (≈130 W m^?1 K^?1), thermal stability (520 °C) and nonflammability, rendering the lightweight nacre‐mimetics promising in flexible electronic devices, particularly for aerospace electronics.     

Extreme‐Performance Rubber Nanocomposites for Probing and Excavating Deep Oil Resources Using Multi‐Walled Carbon Nanotubes

The scarcity of oil resources is going to become one of the main factors threatening the stability of the global economy. To avoid an energy crisis in the future, it is essential to increase oil extraction in much deeper wells, experiencing higher temperatures and pressures. Exploring these deeper areas will demand novel and robust materials. Rubber sealants, or O‐rings, are especially key components in enabling the probing and production of oil in deeper wells, so that higher temperature and pressure reservoirs are reached. In this account, it is demonstrated that carbon nanotubes homogeneously and randomly dispersed in rubber matrices, are able to generate durable sealants that operate satisfactorily at extremely high temperatures and pressures (e.g., 260 °C and 239 MPa). The key issues in these novel composites are: i) the nanotube surface‐control and reactivity, ii) the used of multi‐walled carbon nanotubes (MWNTs)‐embedded in fluorinated rubber, and iii) the formation of a cellulation structure. This rubber nanocomposite with a cellulation structure and having extreme performance leads to a balanced pressure resistance, sealing ability, thermal resistance, and durability, which can contribute to doubling the current average global oil recovery efficiency.     

A Controllable Synthesis of Rich Nitrogen‐Doped Ordered Mesoporous Carbon for CO2 Capture and Supercapacitors

A controllable one‐pot method to synthesize N‐doped ordered mesoporous carbons (NMC) with a high N content by using dicyandiamide as a nitrogen source via an evaporation‐induced self‐assembly process is reported. In this synthesis, resol molecules can bridge the Pluronic F127 template and dicyandiamide via hydrogen bonding and electrostatic interactions. During thermosetting at 100 °C for formation of rigid phenolic resin and subsequent pyrolysis at 600 °C for carbonization, dicyandiamide provides closed N species while resol can form a stable framework, thus ensuring the successful synthesis of ordered N‐doped mesoporous carbon. The obtained N‐doped ordered mesoporous carbons possess tunable mesostructures (p6m and Im m symmetry) and pore size (3.1–17.6 nm), high surface area (494–586 m² g^?1), and high N content (up to 13.1 wt%). Ascribed to the unique feature of large surface area and high N contents, NMC materials show high CO₂ capture of 2.8–3.2 mmol g^?1 at 298 K and 1.0 bar, and exhibit good performance as the supercapacitor electrode with specific capacitances of 262 F g^?1 (in 1 M H₂SO₄) and 227 F g^?1 (in 6 M KOH) at a current density of 0.2 A g^?1.     

Lithium‐Catalyzed Dehydrogenation of Ammonia Borane within Mesoporous Carbon Framework for Chemical Hydrogen Storage

Ammonia borane (AB) has attracted tremendous interest for on‐board hydrogen storage due to its low molecular weight and high gravimetric hydrogen capacity below a moderate temperature. However, the slow kinetics, irreversibility, and formation of volatile materials (trace borazine and ammonia) limit its practical application. In this paper, a new catalytic strategy involved lithium (Li) catalysis and nanostructure confinement in mesoporous carbon (CMK‐3) for the thermal decomposition of AB is developed. AB loaded on the 5% Li/CMK‐3 framework releases ～7 wt % of hydrogen at a very low temperature (around 60 °C) and entirely suppresses borazine and ammonia emissions that are harmful for proton exchange membrane fuel cells. The possible mechanism for enhanced hydrogen release via catalyzed thermal decomposition of AB is discussed.     

Tuning Carbon Materials for Supercapacitors by Direct Pyrolysis of Seaweeds

The sea provides a large variety of seaweeds that, because of their chemical composition, are fantastic precursors of nanotextured carbons. The carbons are obtained by the simple pyrolysis of the seaweeds under a nitrogen atmosphere between 600 and 900 °C, followed by rinsing the product in slightly acidic water. Depending on the origin of the seaweed and on the pyrolysis conditions, the synthesis may be oriented to give an oxygen‐enriched carbon or to give a tuned micro/mesoporous carbon. The samples with a rich oxygenated surface functionality are excellent as supercapacitor electrodes in an aqueous medium whereas the perfectly tuned porous carbons are directly applicable for organic media. In both cases, the specific surface area of the attained carbons does not exceed 1300 m² g⁻¹, which results in high‐density materials. As a consequence, the volumetric capacitance is very high, making these materials more interesting than activated carbons from the point of view of developing small and compact electric power sources. Such versatile carbons, obtained by a simple, ecological, and cheap process, could be well used for environment remediation such as water and air treatment.