Reactive Template-Induced Self-Assembly to Ordered Mesoporous Polymeric and Carbonaceous Materials

As an important method for preparing ordered mesoporous polymeric and carbonaceous materials, the organic template directed self-assembly is facing challenges because of the weak noncovalent interactions between the organic templates and the building blocks. Herein we develop a novel reactive template-induced self-assembly procedure for fabrication of ordered mesoporous polymer and carbon materials. In our approach, the aldehyde end-group of reactive F127 template can react with the resol building block to <i>in-situ</i> form a stable covalent bond during the self-assembly process. This is essential for an enhanced interaction between the resol and the template, thus leading to the formation of an ordered body-centered cubic mesostructure. We also show that the ordered mesoporous carbon product exhibits superior capacitive performance, presenting an attractive potential candidate for high performance supercapacitor electrodes

Preparation of Polymeric Nanoscale Networks from Cylindrical Molecular Bottlebrushes

The design and control of polymeric nanoscale network structures at the molecular level remains a challenging issue. Here we construct a novel type of polymeric nanoscale networks with a unique microporous nanofiber unit employing the intra/interbrush carbonyl cross-linking of polystyrene side chains for well-defined cylindrical polystyrene molecular bottlebrushes. The size of the side chains plays a vital role in the tuning of nanostructure of networks at the molecular level. We also show that the as-prepared polymeric nanoscale networks exhibit high specific adsorption capacity per unit surface area because of the synergistic effect of their unique hierarchical porous structures. Our strategy represents a new avenue for the network unit topology and provides a new application for molecular bottlebrushes in nanotechnology

Teflon: A Decisive Additive in Directly Fabricating Hierarchical Porous Carbon with Network Structure from Natural Leaf

Hierarchically porous carbons are of increasing importance due to their special physicochemical properties. The state-of-the-art approaches for synthesizing hierarchical porous carbon with network structure normally suffer from specific chemistries, rigid reaction conditions, high cost, and multiple tedious steps that limit their large scale production. Herein, we present an interesting insight into the important role of Teflon additive in fabrication of hierarchical porous carbon derived from biomass and, thus, use natural Indicalamus leaves for the first time to successfully synthesize hierarchical porous carbon with a three-dimensional morphology of interconnected nanoparticle units by using a facile and post-treatment-free carbonization technique. It is surprisingly found that the addition of Teflon not only reduces the synthesis procedure by combining post-removal of silica and carbonization in a single step but also plays a decisive role in generating the hierarchical carbonaceous network structure with a specific surface area as high as 1609 m²/g without any extra activation procedures. Benefiting from the combination of well-developed porosity and valuable hierarchical porous morphology, this type of hierarchical porous carbon has demonstrated attractive liquid-phase adsorption properties toward organic molecules

Facile Synthesis of Highly Porous Carbon from Rice Husk

Highly porous carbon materials have attracted great interest for a wide range of important applications. Many examples for their synthesis exist, but these synthetic processes can be quite complex and also very time-consuming. There is still a major challenge to develop a facile yet versatile conceptual approach to produce them. Here, we present an efficient, activation-free, post-treatment-free strategy for the synthesis of highly porous carbon by a simple carbonization of a mixture of rice husk and polytetrafluoroethylene (PTFE) powder. PTFE employed here can <i>in situ</i> generate HF to etch out natural silica during the carbonization treatment of rice husk. This strategy not only reduces the synthesis procedure by combining carbonization and post-removal of silica into a single step but also eliminates completely the usage of hazardous HF or corrosive NaOH or KOH. The as-synthesized carbon materials exhibit a BET surface area as high as 2051 m²/g without any activation treatment, which is about 20 times enhanced in porosity compared to that of the traditional carbon material from rice husk. With the combination of the high porosity and the valuable hierarchical porous structure, the as-prepared porous carbon materials serve well as electrodes for supercapacitive energy storage, including a large capacitance of 317 F/g, good rate performance, and high capacitances per surface area. These findings could provide a new avenue for the facile production of high-performance porous carbon materials with promising applications in various areas

Water-Dispersible, Responsive, and Carbonizable Hairy Microporous Polymeric Nanospheres

Multifunctionalization of microporous polymers is highly desirable but remains a significant challenge, considering that the current microporous polymers are generally hydrophobic and nonresponsive to different environmental stimuli and difficult to be carbonized without damage of their well-defined nanomorphology. Herein, we demonstrate a facile and versatile method to fabricate water-dispersible, pH/temperature responsive and readily carbonizable hairy microporous polymeric nanospheres based on combination of the hyper-cross-linking chemistry with the surface-initiated atom transfer radical polymerization (SI-ATRP). The hyper-cross-linking creates a highly microporous core, whereas the SI-ATRP provides diverse functionalities by surface grafting of hairy functional blocks. The as-prepared materials present multifunctional properties, including sensitive response to pH/temperature, high adsorption capacity toward adsorbates from aqueous solution, and valuable transformation into well-defined microporous carbon nanospheres because of hybrid of carbonizable core and thermo-decomposable protection shell. We hope this strategy could promote the development of both functional microporous polymers and advanced hairy nanoparticles for multipurpose applications

Exfoliating Waste Biomass into Porous Carbon with Multi-Structural Levels for Dual Energy Storage

Waste biomass-derived carbon materials are attracting widespread attention in energy devices due to their renewable environmental protection and heteroatom-rich functionalization. In this work, we propose the preparation of N/O self-doping 3D cage-like porous structures and 2D porous carbon nanosheets by one-step carbonization of activated peanut oil residues with non-toxic K2CO3 at different temperatures (PKs). The fabricated porous carbon materials own a higher specific surface area (1657–2920 m2 g–1), higher nitrogen (1.38–4.41 at. %) and oxygen doping (2.48–4.98 at. %), and higher degree of graphitization. The as-resulted PK-800 possesses a 3D cage-like porous structure, and the electrode at high loads of 12.5 mg cm–2 can achieve an excellent area specific capacitance of 4400 mF cm–2 at 0.5 A g–1. The symmetric components of PK-800 have an ultra-high energy density of 60.31 W h kg–1 at 372 W kg–1 in 1 M TEMATFB/PC. Besides, when applied to the Li-ion battery anode, the prepared highly graphitized 2D porous carbon nanosheets of PK-900 have a high reversible capacity of 580 mA h g–1 at 0.1 A g–1 after 200 cycles. This study proposes a feasible method to activate waste biomass by carbonization in one step and exploit it layer by layer into the desired carbon material for energy storage

Facile Synthesis of Three-Dimensional Heteroatom-Doped and Hierarchical Egg-Box-Like Carbons Derived from Moringa oleifera Branches for High-Performance Supercapacitors

In this paper, we demonstrate that Moringa oleifera branches, a renewable biomass waste with abundant protein content, can be employed as novel precursor to synthesize three-dimensional heteroatom-doped and hierarchical egg-box-like carbons (HEBLCs) by a facile room-temperature pretreatment and direct pyrolysis process. The as-prepared HEBLCs possess unique egg-box-like frameworks, high surface area, and interconnected porosity as well as the doping of heteroatoms (oxygen and nitrogen), endowing its excellent electrochemical performances (superior capacity, high rate capability, and outstanding cycling stability). Therefore, the resultant HEBLC manifests a maximum specific capacitance of 355 F g^–1 at current density of 0.5 A g^–1 and remarkable rate performance. Moreover, 95% of capacitance retention of HEBLCs can be also achieved after 20 000 charge–discharge cycles at an extremely high current density (20 A g^–1), indicating a prominent cycling stability. Furthermore, the as-assembled HEBLC//HEBLC symmetric supercapacitor displays a superior energy density of 20 Wh kg^–1 in aqueous electrolyte and remarkable capacitance retention (95.6%) after 10 000 charge–discharge cycles. This work provides an environmentally friendly and reliable method to produce higher-valued carbon nanomaterials from renewable biomass wastes for energy storage applications

Mechanochemistry: A Green, Activation-Free and Top-Down Strategy to High-Surface-Area Carbon Materials

Renewable resources (e.g., agricultural byproducts) are widely used in the production of commercial activated carbon, but the activation procedures still have serious drawbacks. Here we develop a green, activation-free, top-down method to prepare high-surface-area carbon materials from agricultural wastes through mechanochemistry. The facile mechanochemical process can smash the monolithic agricultural wastes into tiny microparticles with abundant surfaces and bulk defects, which leads to the generation of well-developed hierarchical porous structures after direct carbonization. The as-obtained carbon materials simultaneously present high surface areas (1771 m² g^–1) and large pore volumes (1.88 cm³ g^–1), and thus demonstrate excellent electrochemical performances as the interlayer for lithium–sulfur batteries and much superior creatinine adsorption capabilities to the medicinal charcoal tablets. These results provide a new direction for fabricating high-surface-area porous materials without any toxic reagents or complicated activation procedures, and can spur promising electrochemical and medical applications