Porous Carbon Polyhedrons Research Articles

Nitrogen-doped hollow porous carbon polyhedrons embedded with highly dispersed Pt nanoparticles as a highly efficient and stable hydrogen evolution electrocatalyst

The hydrogen evolution reaction (HER) is a promising alternative method of producing clean and renewable hydrogen resources. Although Pt-based nanomaterials are the most efficient catalysts for HER, their poor stability and durability strongly impede their practical application. In this study, we report a new, efficient strategy to fabricate highly dispersed Pt nanoparticles within unique nitrogen-doped hollow porous carbon polyhedrons (Pt@NHPCP) derived from polymer coated metal-organic frameworks. Pt@NHPCP displays enhanced HER activity compared to commercial Pt/C. Most importantly, Pt@NHPCP exhibits excellent stability and durability, showing no nanostructure change and negligible activity decrease after 5000 potential cycles. The outstanding HER performance of Pt@NHPCP can be attributed to its unique structural features including highly dispersed Pt, nitrogen-doping, large surface area, hollow nanostructure and hierarchical pore system.

CdS nanoparticles immobilized on porous carbon polyhedrons derived from a metal-organic framework with enhanced visible light photocatalytic activity for antibiotic degradation

The CdS/MOF-derived porous carbon (MPC) composite as an efficient visible-light-driven photocatalyst was prepared through the pyrolysis of ZIF-8 and subsequent growth of CdS. The porous and functionalized MPC enables intimate and discrete growth of CdS nanoparticles. This unique structure not only reduces the bulk recombination owing to nano-size effect of CdS, but also suppresses the surface recombination due to the discrete growth of CdS nanoparticles on MPC polyhedrons, which facilitates electron transfer and charge separation. Moreover, such a composite material possessed good adsorption ability toward the antibiotic pollutants because of the amino-functionalized surface. As a result, the as-prepared CdS/MPC composites showed excellent photocatalytic performance for the antibiotic degradation, significantly improving the photoactivity of CdS. Importantly, the CdS/MPC composite with the CdS loading of 20wt% exhibited the highest photocatalytic efficiency of approximately 91% and apparent rate constant of 0.024min−1.

An advanced CoSe embedded within porous carbon polyhedra hybrid for high performance lithium-ion and sodium-ion batteries

A novel composite containing CoSe and porous carbon polyhedra (PCP), denoted as CoSe@PCP, was successfully synthesized using Co-based zeolitic imidazolate framework (ZIF-67) as precursor through a two-step method, including carbonization of ZIF-67 and subsequent selenization. The field-emission scanning electron microscopy and transmission electron microscopy characterizations confirm that CoSe nanoparticles are uniformly dispersed in PCP. When the CoSe@PCP was used as anode material for lithium-ion batteries, it exhibits superior performance with a high reversible capacity of 675mAhg−1 at 200mAg−1 after 100 cycles and 708.2mAhg−1 at 1Ag−1 after 500 cycles as well as excellent cycling stability. Additionally, the CoSe@PCP also demonstrates excellent performance as anode material for sodium-ion batteries. A reversible capacity of 341mAhg−1 can be obtained over 100 cycles at 100mAg−1 with high cycling stability. The excellent battery performance of CoSe@PCP should be attributed to the synergistic effect of nanostructured CoSe and PCP derived from ZIF-67, in which the nanostructured CoSe possesses high reactivity towards lithium and sodium ions and the PCP can provide a continuous conductive matrix to facilitate the charge transfer and an effective buffering to mitigate the structure variation of CoSe during cycling.

ZIF-derived graphene coated/Co9S8 nanoparticles embedded in nitrogen doped porous carbon polyhedrons as advanced catalysts for oxygen reduction reaction

Development of efficient electrocatalysts for the oxygen reduction reaction (ORR) is vitally important for the commercialization of metal–air batteries. In this work, we demonstrate a novel graphene coated/Co9S8 nanoparticles-embedded nitrogen doped porous carbon dodecahedron hybrid (Co9S8/NPCP@rGO) prepared by the pyrolysis and sulphuration of precursors composing of graphene oxide and zeolitic imidazolate-frameworks (ZIF). The Co9S8/NPCP@rGO hybrid is used as a highly efficient nonprecious metal electrocatalyst for oxygen reduction and exhibits more positive onset potential and half-wave potential, higher limiting current density, lower Tafel slope, and better durability and methanol tolerance in alkaline media in comparison to the commercial 20 wt.% Pt/C catalyst. The greatly improved electrocatalytic performance of Co9S8/NPCP@rGO can be attributed to the unique structure with Co9S8 nanoparticles dispersed uniformly inside nitrogen doped porous carbon matrix, and the synergistic effect between Co9S8/NPCP polyhedral hybrid and rGO.

Flexible and Binder-Free Hierarchical Porous Carbon Film for Supercapacitor Electrodes Derived from MOFs/CNT

Rational design of free-standing porous carbon materials with large specific surface area and high conductivity is a great need for ligh-weight suprecapacitors. Here, we report a flexible porous carbon film composed of metal-organic framework (MOF)-derived porous carbon polyhedrons and carbon nanotubes (CNTs) as binder-free supercapacitor electrode for the first time. Due to the synergistic combination of carbon polyhedrons and CNT, the obtained carbon electrode shows a specific capacitance of 381.2 F g-1 at 5 mV s-1 and 194.8 F g-1 at 2 A g-1 and outstanding cycling stability with a Coulombic effciency above 95% after 10000 cycles at 10 A g-1. The assembled aqueous symmetrical supercapacitor exhibits an energy density of 9.1 Wh kg-1 with a power density of 3500 W kg-1. The work opens a new way to design flexible MOF-based hierarchical porous carbon film as binder-free electrodes for high-performance energy storage devices.

Strings of Porous Carbon Polyhedrons as Self‐Standing Cathode Host for High‐Energy‐Density Lithium–Sulfur Batteries

AbstractRational design of cathode hosts with high electrical conductivity and strong sulfur confinement is a great need for high‐performance lithium–sulfur batteries. Herein, we report a self‐standing, hybrid‐nanostructured cathode host comprised of metal–organic framework (MOF)‐derived porous carbon polyhedrons and carbon nanotubes (CNTs) for the significant improvement of both the electrode cyclability and energy density. The strong coupling of the intertwined CNTs and strung porous carbon polyhedrons as a binder‐free thin film significantly enhances the long‐range electronic conductivity and provides abundant active interfaces as well as robust electrode integrity for sulfur electrochemistry. Attributed to the synergistic combination of the CNTs and carbon polyhedrons, the obtained sulfur electrodes exhibit outstanding cyclability, an excellent high‐rate response up to 10 C, and an ultra‐high volumetric capacity of 960 Ah L−1.

Strings of Porous Carbon Polyhedrons as Self-Standing Cathode Host for High-Energy-Density Lithium-Sulfur Batteries.

Rational design of cathode hosts with high electrical conductivity and strong sulfur confinement is a great need for high-performance lithium-sulfur batteries. Herein, we report a self-standing, hybrid-nanostructured cathode host comprised of metal-organic framework (MOF)-derived porous carbon polyhedrons and carbon nanotubes (CNTs) for the significant improvement of both the electrode cyclability and energy density. The strong coupling of the intertwined CNTs and strung porous carbon polyhedrons as a binder-free thin film significantly enhances the long-range electronic conductivity and provides abundant active interfaces as well as robust electrode integrity for sulfur electrochemistry. Attributed to the synergistic combination of the CNTs and carbon polyhedrons, the obtained sulfur electrodes exhibit outstanding cyclability, an excellent high-rate response up to 10 C, and an ultra-high volumetric capacity of 960 Ah L-1 .

Engineering metal organic framework derived 3D nanostructures for high performance hybrid supercapacitors

A high-performance hybrid Li-ion capacitor was fabricated based on a metal–organic framework derived 3D porous carbon polyhedron and MoS2–ZIF nanostructures.

Porous Carbon Polyhedrons with High-Level Nitrogen-Doping for High-Performance Sodium-Ion Battery Anodes

Porous Carbon Polyhedrons with High-Level Nitrogen-Doping for High-Performance Sodium-Ion Battery Anodes

Cobalt diselenide nanoparticles embedded within porous carbon polyhedra as advanced electrocatalyst for oxygen reduction reaction

Abstract Highly efficient and cost-effective electrocatalyst for the oxygen reduction reaction (ORR) is crucial for a variety of renewable energy applications. Herein, strongly coupled hybrid composites composed of cobalt diselenide (CoSe2) nanoparticles embedded within graphitic carbon polyhedra (GCP) as high-performance ORR catalyst have been rationally designed and synthesized. The catalyst is fabricated by a convenient method, which involves the simultaneous pyrolysis and selenization of preformed Co-based zeolitic imidazolate framework (ZIF-67). Benefiting from the unique structural features, the resulting CoSe2/GCP hybrid catalyst shows high stability and excellent electrocatalytic activity towards ORR (the onset and half-wave potentials are 0.935 and 0.806 V vs. RHE, respectively), which is superior to the state-of-the-art commercial Pt/C catalyst (0.912 and 0.781 V vs. RHE, respectively).

Reduced graphene oxide wrapped MOFs-derived cobalt-doped porous carbon polyhedrons as sulfur immobilizers as cathodes for high performance lithium sulfur batteries

Reduced graphene oxide (RGO) wrapped metal-organic frameworks (MOFs) derived cobalt doped porous carbon polyhedrons synthesized via a carbonization process, are for the first time used for sulfur immobilizers (RGO/C–Co-S) as cathodes for high performance lithium-sulfur (Li–S) batteries. The RGO/C–Co–S cathode exhibits greatly improved electrochemical performance, showing excellent specific capacity of 949mAh g−1 at 300th cycle at a current density 0.3Ag−1, displaying enhanced rate capability with specific capacity of 772, 704 and 606mAh g−1 at current density of 0.5, 1 and 2Ag−1, respectively. The synergetic effect of MOFs-derived porous carbon, homogeneously distributed Co nanoparticles and RGO nanosheets simultaneously contributes to the confinement of sulfur species. The presence of abundant mesopores and micropores is conducive to immobilize large amounts of S species. The homogenously inlaid ultrafine Co nanoparticles can further immobilize sulfur by chemical interactions between Co and S/polysulfides. The RGO nanosheets tightly wrapped on carbon hosts act as barrier layers to prevent polysulfides from diffusing out of the matrix, further suppressing shuttle effect. The porous structure and the RGO can effectively alleviate the volume changes resulted from charge–discharge process. This design strategy can be inspiring for MOF-derived materials in energy storage applications.

Asymmetric supercapacitors based on carbon nanotubes@NiO ultrathin nanosheets core-shell composites and MOF-derived porous carbon polyhedrons with super-long cycle life

Aqueous electrolyte based asymmetric supercapacitors (ASCs) has recently attracted increasing interest by virtue of their operation voltage and high ionic conductivity. Herein, we developed a novel ASC based on carbon nanotubes@nickel oxide nanosheets (CNT@NiO) core–shell composites as positive electrode and porous carbon polyhedrons (PCPs) as negative electrode in aqueous KOH solution as electrolyte. The CNT@NiO core–shell hybrids were prepared through a facile chemical bath deposition method followed by thermal annealing, while PCPs were obtained by direct carbonization of Zn-based metal-organic frameworks (MOFs). Owing to their unique microstructures, outstanding electrochemical properties have been achieved in three-electrode configuration, e.g., 996 F g−1 at 1 A g−1, 500 at 20 A g−1 for the CNT@NiO electrode within 0–0.5 V window, and 245 F g−1 at 1 A g−1 for the PCPs electrode within −1–0 V window. Resulting from these merits, the as-fabricated CNT@NiO//PCPs ASC exhibits maximum energy density of 25.4 Wh kg−1 at a power density of 400 W kg−1 and even remains 9.8 Wh kg−1 at 16,000 W kg−1 (a full charge–discharge within 4.4 s) in the wide voltage region of 0–1.6 V. More importantly, the CNT@NiO//PCPs asymmetric supercapacitor shows ultralong cycling stability, with 93% capacitance retention after 10,000 cycles.

Hybrid Electrocatalysis: An Advanced Nitrogen‐Doped Graphene/Cobalt‐Embedded Porous Carbon Polyhedron Hybrid for Efficient Catalysis of Oxygen Reduction and Water Splitting (Adv. Funct. Mater. 6/2015)

Hybrid Electrocatalysis: An Advanced Nitrogen‐Doped Graphene/Cobalt‐Embedded Porous Carbon Polyhedron Hybrid for Efficient Catalysis of Oxygen Reduction and Water Splitting (Adv. Funct. Mater. 6/2015)

Metal-organic framework-derived porous carbon polyhedra for highly efficient capacitive deionization.

Porous carbon polyhedra (PCP) were prepared through direct carbonization of zeolitic imidazolate framework-8 and used as an electrode material for capacitive deionization. The results show that PCP treated at 1200 °C exhibit the highest electrosorption capacity of 13.86 mg g(-1) when the initial NaCl concentration is 500 mg l(-1), due to their high accessible surface area and low charge transfer resistance.

An Advanced Nitrogen‐Doped Graphene/Cobalt‐Embedded Porous Carbon Polyhedron Hybrid for Efficient Catalysis of Oxygen Reduction and Water Splitting

A novel hybrid electrocatalyst consisting of nitrogen‐doped graphene/cobalt‐embedded porous carbon polyhedron (N/Co‐doped PCP//NRGO) is prepared through simple pyrolysis of graphene oxide‐supported cobalt‐based zeolitic imidazolate‐frameworks. Remarkable features of the porous carbon structure, N/Co‐doping effect, introduction of NRGO, and good contact between N/Co‐doped PCP and NRGO result in a high catalytic efficiency. The hybrid shows excellent electrocatalytic activities and kinetics for oxygen reduction reaction in basic media, which compares favorably with those of the Pt/C catalyst, together with superior durability, a four‐electron pathway, and excellent methanol tolerance. The hybrid also exhibits superior performance for hydrogen evolution reaction, offering a low onset overpotential of 58 mV and a stable current density of 10 mA cm−2 at 229 mV in acid media, as well as good catalytic performance for oxygen evolution reaction (a small overpotential of 1.66 V for 10 mA cm−2 current density). The dual‐active‐site mechanism originating from synergic effects between N/Co‐doped PCP and NRGO is responsible for the excellent performance of the hybrid. This development offers an attractive catalyst material for large‐scale fuel cells and water splitting technologies.

Well-defined carbon polyhedrons prepared from nano metal–organic frameworks for oxygen reduction

Well-defined porous carbon polyhedrons are synthesized directly from MOF nanocrystals and show high oxygen reduction reaction (ORR) catalytic activity in acid media.