Ultrathin Porous Carbon Research Articles

Ultrathin nitrogen-rich porous carbon nanosheets with fluorine doping for high-performance potassium storage

Potassium ion batteries (KIBs) are considered as a promising substitute for lithium ion batteries (LIBs) due to potassium abundant and low-cost. Nevertheless, serious volume expansion and sluggish kinetics caused by repeated insertion/extraction of K+ with larger radius frequently restrict the K+ storage performance. Herein, we explored ultrathin nitrogen-rich carbon nanosheets with fluorine doping (CPTHB-F) as the anode in KIBs by carbonizing a rigid polymer porous framework (PTHB) and polytetrafluoroethylene (PTFE). The CPTHB-F possesses short distance of potassium ion mobility, large interlayer spacing and more exposed active sites. As a result, KIBs with CPTHB-F anode exhibits a high specific capacity of 115.3 mA h g–1 at a high current density of 5.0 A g–1. Moreover, the long-term stability of CPTHB-F is excellent which shows a negligible capacity loss of 0.05% per cycle corresponding to a high capacity of 137.3 mA h g–1 after 690 cycles at the current density of 0.5 A g–1. This work provides a new strategy to construct carbon materials for the reversible potassium ion storage.

A bubble-assisted strategy to prepare porous ultrathin carbon nitride for highly-active photocatalytic hydrogen production

Porous and ultrathin polymetric carbon nitride has recently emerged as a promising photocatalyst. However, the complex synthesis strategy of porous ultrathin carbon nitride (PTCN) impedes its further application in photocatalytic water splitting. It is a challenge to find a facile and powerful synthesis strategy of porous ultrathin polymetric carbon nitride. In this work, we demonstrate a bubble-assisted strategy for porous ultrathin polymetric carbon nitride. The thermal polymerization process under the blowing effect of NH4Cl endows PTCN with the porous and ultrathin structure. The larger accessible specific surface area (SSA) provides abundant active edges and sites, decreasing the diffusion distance of reactants and carriers. Compared to the bulk carbon nitride (bulk CN), PTCN possesses higher SSA, a broader bandgap, and improved photogenerated carriers transfer efficiency. In addition, the calculation of Gibbs free energy manifests the improved hydrogen absorption ability. As a result, a remarkable hydrogen evolution rate at 22.0 mmol h−1 g−1 is achieved, which is 6 times higher than that of bulk carbon nitride.

Ultra-Thin Hierarchical Porous Carbon Coated Metal Phosphide Self-Assembled Efficient Tri-Functional Electrodes for Overall Water Splitting and Rechargeable Zinc-Air Batteries

Ultra-Thin Hierarchical Porous Carbon Coated Metal Phosphide Self-Assembled Efficient Tri-Functional Electrodes for Overall Water Splitting and Rechargeable Zinc-Air Batteries

Molten Salt Synthesis of Cofe Alloy Embedded in 2d Ultrathin N-Doped Porous Carbon Nanosheets for Efficient Cooperative Oxygen Electrocatalysis

Molten Salt Synthesis of Cofe Alloy Embedded in 2d Ultrathin N-Doped Porous Carbon Nanosheets for Efficient Cooperative Oxygen Electrocatalysis

Core-Shell Structured Fe-N-C Nanocatalyst Wrapped by Ultrathin Porous Carbon Shell as a Robust Electrocatalyst for Oxygen Reduction Reaction

Core-Shell Structured Fe-N-C Nanocatalyst Wrapped by Ultrathin Porous Carbon Shell as a Robust Electrocatalyst for Oxygen Reduction Reaction

Preparation of Ultra-Thin Porous Carbon Nitride and its Photocatalytic H2o2 Production and Photodegradation of Rhb

Preparation of Ultra-Thin Porous Carbon Nitride and its Photocatalytic H2o2 Production and Photodegradation of Rhb

A host–guest self-assembly strategy to enhance π-electron densities in ultrathin porous carbon nitride nanocages toward highly efficient hydrogen evolution

Converting solar energy into renewable clean fuels of hydrogen via photocatalytic water splitting provides the most prospective strategy for tackling the energy and environmental issues. The performance of most photocatalysts is closely related to the intrinsic activity and active edge sites; however, simultaneously regulating them to realize synergic effects remains significant scientific and technological challenge. Here, we report an elaborate design and synthesis of porous carbon nitride nanocages (CN-C) with abundant π-electron densities by a novel host–guest supramolecular self-assembly strategy, overcoming one of the major challenges of traditional copolymeration method, i.e., the required highly matched chemical structure and physical properties of the π-electron-rich monomers to nitrogen-rich monomers. This strategy primarily depends on the cooperation of the host supramolecular precursor growth and the self-regulation of guest supermolecules to compensate the inherent shortage of each component. Interestingly, the structural topology and electron densities of CN-C are found to be easily modulated by only varying the amount of urea. Benefiting from the synergic effects of hierarchically porous structures with enriched active sites and excellent accessibility, increased abundant π-electron densities and improved visible-light absorption, the CN-C nanocages exhibit remarkable photocatalytic hydrogen evolution activity under visible light exposure with H2 generation rate of 1135 μmol h−1g−1, which is 19 times higher than that of pristine CN (59.8 μmol h−1g−1). This powerful strategy provides a profound molecular-level insight into the control of morphology and π-electron densities within carbon-based materials.

Enriching Atomic Cobalt in an Ultrathin Porous Carbon Shell for Enhanced Electrocatalysis.

Developing nonprecious electrocatalysts operating in acidic and alkaline media for an oxygen reduction reaction (ORR) is essential for sustainable energy technologies. Increasing the metal active site density is an effective strategy to enhance the activity, but it remains challenging because of metal sintering during pyrolysis. Here, we report a novel strategy of enriching atomically dispersed cobalt species in nitrogen-doped carbon for improving the electrocatalytic performance. A hollow carbon nanosphere with reduced shell thickness was obtained by taking advantage of the carbothermic reaction between carbon and ZnO template, and the resulting cobalt enrichment in the ultrathin carbon shell leads to an increase of the density of Co atoms. Together with advantageous microstructure features such as high surface area and multiscale porosity, the corresponding catalyst demonstrated promising oxygen reduction reaction performance in strong acidic and alkaline electrolytes and has two times higher kinetic current density than the nonenriched one. The present work provides an attractive and facile route to engineer active site in electrocatalysts.

Ultrathin 2D catalysts with N-coordinated single Co atom outside Co cluster for highly efficient Zn-air battery

• 1. Ultrathin electrocatalysts with Co active center were prepared from a new MOF nanosheet. • 2. Ultrathin Co@N-C700 displays superior ORR activity. • 3. A ZAB with Co@N-C700 air cathode delivers high power density. • 4. Synergetic effect contributes excellent activity. Zn-air battery (ZAB) has been considered as a kind of important mobile energy system. However, one of the major challenges is to improve the efficiency of involved oxygen reduction reaction (ORR), which requires stable and highly effective electrocatalysts that may work with air as O 2 supplier. Herein, we report the design and synthesis of a group of ultrathin 2D electrocatalysts (8.2 to 18.5 nm) from a new metal–organic framework (MOF) ([Co 2 (TCPP)(DABCO)], named NTU-70) that can be facilely prepared in large-scale. Compared with its block counterpart and other ultrathin electrocatalysts, Co@N-C700 exhibits superior ORR activity ( E 1/2 = 0.78 V) and outstanding durability, which originates from the synergistic effect of N-coordinated single Co atom outside Co cluster and ultrathin porous carbon support. Encouragingly, a rechargeable ZAB assembled with Co@N-C700 air cathode delivers a steady discharge voltage plateau of 1.22 V and a low discharge/charge polarization (0.80 V) within 240 h, outperforming Pt/C catalysts. The current strategy for finely design and synthesis of MOF-derived ultrathin electrocatalysts provides a prospect in developing metal-air batteries with a higher power density and may also pave the way for the feasible application of these ultrathin catalysts in energy conversion/storage devices.

Three-dimensional porous ultrathin carbon networks reinforced PBAs-derived electrocatalysts for efficient oxygen evolution

Prussian blue analogues (PBAs), identified with a face-centered cubic (fcc) unit cell with transition-metal ions bridged by cyano ligands, can be used as precursors in nanomaterials for catalysis applications, but the performance is usually limited by the original large size of PBAs. We provide here a controllable thermal decomposition route for PBAs to obtain highly dispersed small-sized nanoparticles with high catalytic activity. CoFe PBA nanocubes as catalyst precursors are grown within three-dimensional porous ultrathin N-doped carbon networks (3DNC), which is constructed using mixed soluble salts as templates. The use of 3DNC as supporting matrix can not only increase the electrical conductivity and transport properties of reaction-relevant species within the catalyst material, but also supply huge specific surface and restrict the size of loaded nanoparticles. Followed by calcination in the reductive atmosphere, the PBA nanocubes are decomposed to form numerous small-sized CoFe/CoFeOx nanoparticles that are uniformly dispersed. It is interesting to find that this thermal decomposition process is assisted by 3DNC matrix because of its excellent thermal conductive property. Benefiting from the synergetic bimetal alloy/oxide composition, advantageous structural feature and favorable interfacial integration of the hybrid material, the CoFe/CoFeOx@3DNC exhibits remarkable electrocatalytic activity and stability for the oxygen evolution reaction (OER) in alkaline media. The decomposition of PBAs precursor to small-sized nanoparticles and the use of 3DNC as supporting matrix and thermal conductive agent are appealing. The integration of these two components provides an interesting hybrid catalyst system with controllable composition, delicate morphology and favorable interfacial property.

Bio-inspired construction of electrocatalyst decorated hierarchical porous carbon nanoreactors with enhanced mass transfer ability towards rapid polysulfide redox reactions

Li-S batteries are considered as a highly promising candidate for the next-generation energy storage system, attributing to their tremendous energy density. However, the two-dimensional island nucleation-growth process of lithium sulfide leads to a thick insulating film covering the electrode, inducing slow electrons transfer and mass-transfer of ions and liquid sulfur species in working Li-S cells. Here, we demonstrate a bio-inspired strategy of constructing ant-nest-like hierarchical porous ultrathin carbon nanosheet networks with the implants of metallic nanoparticles electrocatalysts (HPC-MEC) as efficient nanoreactors enabling rapid mass transfer, via a simple and green NaCl template. Such nanoreactors with a large active surface area could effectively anchor polysulfides for mitigating the shuttle effect, facilitating uniformly thin Li2S film, and promoting the mass transfer for fast sulfur species conversions. This helps contribute to a continuously high sulfur utilization in Li-S batteries with the HPC-MEC reactors. As a typical exhibition, cobalt embedded hierarchical porous carbon (HPC-Co) could realize to deliver a remarkably high specific capacity of 1,540.6 mAh·g−1, an excellent rate performance of 878.8 mAh·g−1 at 2 C, and high area capacity of 11.6 mAh·cm−2 at a high sulfur load of 10 mg·cm−2 and low electrolyte/sulfur ratio of 5 µL·mg−1.

Inside Back Cover: Ultrathin Porous Carbon Nitride Bundles with an Adjustable Energy Band Structure toward Simultaneous Solar Photocatalytic Water Splitting and Selective Phenylcarbinol Oxidation (Angew. Chem. Int. Ed. 9/2021)

Synchronous and efficient utilization of photogenerated electrons and holes is a challenging task in the field of photocatalysis. In their Research Article on page 4815, Baojiang Jiang, Honggang Fu, and co-workers describe the synthesis of ultrathin porous carbon nitride bundles for simultaneous solar photocatalytic water splitting and selective phenylcarbinol oxidation. The bundles have adjustable band gaps (2.25–2.75 eV) and hollow microtubes with ultrathin pore walls.

Ultrathin Porous Carbon Nitride Bundles with an Adjustable Energy Band Structure toward Simultaneous Solar Photocatalytic Water Splitting and Selective Phenylcarbinol Oxidation

AbstractActiniae‐like carbon nitride (ACN) bundles were synthesized by the pyrolysis of an asymmetric supramolecular precursor prepared from L‐arginine (L‐Arg) and melamine. ACN has adjustable band gaps (2.25 eV–2.75 eV) and hollow microtubes with ultrathin pore walls, which enrich reaction sites, improve visible‐light absorption and enhance charge separation. In the presence of phenylcarbinol, ACN exhibited excellent water‐splitting ability (95.3 μmol h−1) and in the meanwhile phenylcarbinol was selectively oxidized to benzaldehyde (conversion of 90.9 %, selectivity of 99.7 %) under solar irradiation. For the concurrent reactions, 2D isotope labeling, separation, and detection were conducted to confirm that the proton source of released hydrogen is water. The mechanism of water splitting and phenylcarbinol oxidation was also investigated.

Ultrathin Porous Carbon Nitride Bundles with an Adjustable Energy Band Structure toward Simultaneous Solar Photocatalytic Water Splitting and Selective Phenylcarbinol Oxidation.

Actiniae-like carbon nitride (ACN) bundles were synthesized by the pyrolysis of an asymmetric supramolecular precursor prepared from L-arginine (L-Arg) and melamine. ACN has adjustable band gaps (2.25 eV-2.75 eV) and hollow microtubes with ultrathin pore walls, which enrich reaction sites, improve visible-light absorption and enhance charge separation. In the presence of phenylcarbinol, ACN exhibited excellent water-splitting ability (95.3 μmol h-1 ) and in the meanwhile phenylcarbinol was selectively oxidized to benzaldehyde (conversion of 90.9 %, selectivity of 99.7 %) under solar irradiation. For the concurrent reactions, 2 D isotope labeling, separation, and detection were conducted to confirm that the proton source of released hydrogen is water. The mechanism of water splitting and phenylcarbinol oxidation was also investigated.

A multifunctional activation strategy of ultrathin carbon layers-intertwined carbon microspheres clusters towards markedly enhanced capacitance

Exploiting a facile and effective synthetic strategy integrated with pore-forming and nitrogen doping is highly desirable for developing superior electrode materials. Here, we proposed an ingenious multifunctional activation strategy to synthesize ultra-thin graphite-like carbon layers interwoven N-doped porous carbon microspheres clusters (donated by NCSC) by pyrolyzing self-polymered dopamine nanosphere precursors and g-C3N4, in which g-C3N4 simultaneously served as a pore-foaming agent, nitrogen source and a regulator of nitrogen configuration. The as-prepared NCSC exhibited three-dimensional interwoven porous structures with more favorable hydrophilic interface, high porosity with interconnected open pore structures, and pyrrole-N and pyridine-N dominated high nitrogen doping content (5.70 at.%). In the three-electrode test system, NCSC delivered significantly increased capacitance (235.4F g−1 at 1A g−1) compared to that of dopamine nanospheres derived carbon microspheres clusters(CSC) (124.7F g−1 in 1A g−1), and an excellent cycling durability (97% retention at 20A g−1 after 10,000 cycles). More impressively, the NCSC-based symmetrical supercapacitor with 1.0 M neutral Na2SO4 electrolyte can realize a wide voltage range of 1.8 V, rendering a specific energy density of 14.64 Wh kg−1 at 450 W kg−1. Such kind of integrated multi-functional activation strategy can provide new ideas for developing advanced materials to significantly boost capacitance performance.

Fabrication of porous ultrathin carbon nitride nanosheet catalysts with enhanced photocatalytic activity for N- and O-heterocyclic compound synthesis

A simple and efficient photocatalytic method for the synthesis of N- and O-heterocyclic compound via porous ultrathin carbon nitride nanosheets (p-CNNs) was demonstrated.

Sustainable development of ultrathin porous carbon nanosheets with highly accessible defects from biomass waste for high-performance capacitive desalination

Biomass-derived defective porous carbons with numerous superiorities have received widespread attention for capacitive deionization (CDI).

Template-Free Preparation of Hierarchical Porous Carbon Nanosheets for Lithium-Sulfur Battery.

Porous carbon nanosheets have the advantages of longitudinal continuity, transverse ultrathin, high specific surface area, and surface atomic activity, as well as the synergistic effect of micro and nanoproperties, so the research on their preparation, structure, and properties has attracted wide attention. A series of ultrathin hierarchical porous carbon nanosheets (HPCNs) is fabricated through carbonization of precursors obtained through the Friedel-Crafts reaction-assisted loading of polystyrene on graphene oxide. Hierarchical pore structures consist of three parts: (1) the micropores (1.3 nm), which were provided by porous polystyrene through the Friedel-Crafts reaction; (2) the mesopores (3.8 nm), which were provided by slab pores from the stack of carbon nanosheets; and (3) the pores (>5 nm) formed from the random stack of carbon nanosheets. Controlling the carbonization time and temperature adds to a prominent increase in specific surface area from 405.8 to 1420 m2 g-1. It was found that excessive carbonization would destroy the hierarchical pore structure. These porous carbon materials were used as cathode materials for lithium-sulfur battery and showed good performance. HPCN/sulfur cathode has good rate performance and cycle performance, and the capacity retention rate is 87% after the current density rises from 1 to 3 C and 91% after 200 cycles.

Metallic Ni-Fe-Co Nanoparticles Doped with Ultrathin Carbon Nanosheets: A Highly Efficient Electrocatalyst for Overall Water Splitting

Consistent design and cost-effective multifunctional electrocatalyst that comprises of highly abundant earth elements are greatly need for sustainable energy conversion applications. The present study reports a facile single-step strategy for in-situ growth of NiFeCo nanoparticles doped-ultrathin carbon nanosheets (NFC@CNSs) with hierarchical like structure by pyrolysis method. NFC@CNSs catalyst at optimum condition exhibits an outstanding activity with a low overpotential 124 and 256 mV to achieve a current density of 10 mA cm-2 with a small tafel slope 119.22 and 67.83 mV dec-1 for hydrogen and oxygen evolution reactions, respectively, in 1.0 M KOH. Furthermore, NFC@CNSs exhibits the large electrochemical active surface area of 21.30 mF cm-2, highly specific SBET surface area 145.39 m² g-1, low charge transfer resistance 46.87 ohms which forms the superior catalytic performance. The two-electrode system constructed as anode and cathode in an alkaline electrolyzer can achieve a current density of 10 mA cm-2 by a fairly low applied cell-voltage of 1.566 V under the real water splitting condition. The result revealed that, the strong coupling between NiFeCo alloy nanoparticles and carbon nanosheets might have been responsible for formulating such a remarkable electrochemical performances, electronic structure, and robust stability toward overall water splitting. Additionally, ultrathin porous carbon nanosheets structure does not only provides substantial active sites, but also facilitates the charge transfer process during diffusion and saturation of electrolytes which ultimately boost-up catalytic performances. This work provides a facile single-pot approach to construct metal-doped nanostructured materials with earth-abundant elements for sustainable industrial applications.

Photocatalytic conversion of biomass-based monosaccharides to lactic acid by ultrathin porous oxygen doped carbon nitride

Application of photocatalysis to biorefinery conforms to the requirement of sustainable development of the society. It is of great significance, yet limited success has been achieved. Here, we report oxygen atom doped on the ultrathin porous carbon nitride (Ut-OCN) as an efficient photocatalyst for lactic acid production. The Ut-OCN photocatalyst represents an increase in the absorption range of visible-light via tunable band structure. Remarkably, the photocatalyst exhibited effective activity with lactic acid yield above 89.7 %, and this system is universal for the synthesis of lactic acid from biomass-based monosaccharides. Catalytic poisoning and recycling experiments revealed that the selectivity of ·O2− is superior to ·OH, 1O2, h+ in proper order. The photocatalyst is highly stable and recyclable. Moreover, the yield of lactic acid of one-thousand-fold scale-up experiment irradiated by sunlight retained 98.4 % of one-time experiment. It is believed that this work paves a way for the lactic acid production via photocatalysis.