Mesoporous 3D Research Articles

A novel Z-scheme CeO2/g-C3N4 heterojunction photocatalyst for degradation of Bisphenol A and hydrogen evolution and insight of the photocatalysis mechanism

CeO2/g-C3N4 heterojunction photocatalyst had been successfully fabricated through a one-step in-situ pyrolysis formation of 3D hollow CeO2 mesoporous nanospheres and 2D g-C3N4 nanosheets together with simultaneous removal of carbon sphere templates after heat treatment. The sample shows high catalytic performances for photocatalytic hydrogen generation and photocatalytic oxidation of Bisphenol A (BPA) under visible light irradiation, and the catalytic degradation route of BPA was suggested by the degradation products determined by GC–MS. The enhancing catalytic activity was attributed to the effective interfacial charge migration and separation. Finally, it was proposed that the CeO2/g-C3N4 heterojunction photocatalyst could follow a more appropriate Z-scheme charge transfer mechanism, which was confirmed by the analysis of experiment and theoretical calculation results.

Mesoporous 3D titanium dioxide embed carbon nanofibers with superior polysulfide adsorption ability for high electrochemical performance Li-S batteries

The rechargeable lithium-sulfur batteries are promising candidate for the energy storage applications due to their low cost and high energy density. However, the lithium-sulfur batteries show poor electrochemical performance, caused by the polysulfide dissolution and low electrical conductivities of the sulfur cathode. Herein, we develop a new strategy to solving these two issues by designing titanium dioxide embed carbon nanofibers/S (CNFs@TO/S) hybrid composites. In this unique hybrid structure, the mesoporous 3D carbon nanofibers could provide fast electron conduction paths and structural stability. The titanium dioxide could act as polysulfide absorber via chemical bond between TiO2 and polysulfide. Owing to these synthetic effect, the as-prepared CNFs@TO/S cathodes exhibit advanced electrochemical performances.

Direct synthesis of hierarchical zeolites through mesoporous 3D wormhole framework using single-head quaternary ammonium salt as structure-directing agent

Hierarchical aluminosilicate zeolites with uniform mesoporosity were successfully synthesized by one-stage crystallization under constant temperature with a novel single-head quaternary ammonium salt ([C18H37–N+(CH3)2–C6H12–N(CH3)2]Br−) as mesoporogen and structure-directing agent (SDA). Through precisely controlling the molar ratio of Si/Al and synthetic time, the mesoporous 3D wormhole framework (MCM-48) and crystalline microporous MFI structure were simultaneously constructed, revealed by a series of in-depth characteristic studies. Combining the advantages of the significantly improved diffusion from the mesoporous MCM-48 and the strong framework acidity of the crystalline microporous MFI zeolite, the hierarchical aluminosilicate zeolites exhibited outstanding catalytic activity with good reusability towards bulky aldol condensation compared with the conventional meso- or microporous zeolites.

Micropores within N,S co-doped mesoporous 3D graphene-aerogel enhance the supercapacitive performance

Micropores within N,S co-doped mesoporous 3D graphene-aerogel enhances supercapacitive performance.

Nb2O5 as a radical modulator during oxidative dehydrogenation and as a Lewis acid promoter in CO2 assisted dehydrogenation of octane over confined 2D engineered NiO–Nb2O5–Al2O3

Ordered mesoporous 2D NiO–Nb2O5–Al2O3 nano-composites were used for CO2 assisted dehydrogenation of n-octane; and the close proximity of Ni and Nb2O5 in the optimised catalyst promoted CO2 dissociation and substantially prolonged alkane activation.

2D Mesoporous Covalent Organic Framework with High Iodine Capture Capability

2D Mesoporous Covalent Organic Framework with High Iodine Capture Capability

2D Mesoporous Nanomesh from N-Doped Carbon-Encapsulated V2O3 Nanowires as an Anode for Lithium-Ion Batteries

Vanadium (III) oxide nanomaterials have been investigated and considered as potential anode materials for Li-ion batteries (LIBs). Fabrication of two-dimensional (2D) mesoporous nanomeshes from car...

Atomically dispersed and nanoscaled Co species embedded in micro-/mesoporous carbon nanosheet/nanotube architecture with enhanced oxygen reduction and evolution bifunction for Zn-Air batteries

Developing active and stable non-precious metal bifunctional electrocatalysts towards the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) still remains a crucial challenge. Herein, we propose a simple strategy of integrating atomically dispersed and nanoscaled Co species embedded in micro-/mesoporous carbon nanosheet/nanotube architecture. Revealed by control and SCN- poisoning experiments, N species and atomically dispersed Co species are the main active centers for ORR; whereas the metal Co nanocrystals are the chief active species for OER. Additionally, the balanced micro/mesopore distribution offers fast mass diffusion, and carbon nanosheet/nanotube architecture supplies favorable 3D electrical conduct. As a result, the as-prepared CoNC (1:4) exhibits a positive half-wave potential of 0.87 V (vs RHE) for ORR, and a low potential of 1.55 V (vs RHE) at 10 mA cm−2 for the OER. Importantly, the flexible Zn-air battery using the catalyst exhibits a peak power density of 117 mW cm−2, a higher round-trip efficiency of 68% cycling at 2 mA/cm−2, and an excellent cycling stability with 3% decrease after 126 cycles test. This work provides a general strategy to design bifunctional catalysts by integrating atomically dispersed and nanoscaled transitional metal species together with N-doped micro-/mesoporous 3D carbon.

Induced symmetric 2D Mesoporous Graphitic Carbon Spinel Cobalt Ferrite (CoFe2O4/2D-C) with high porosity fabricated via a facile and swift sucrose templated microwave combustion route for an improved supercapacitive performance

Symmetric 2D Mesoporous Graphitic Carbon spinel cobalt ferrite (CoFe2O4/2D-C) with high porosity has been fabricated via a facile and swift sucrose template microwave combustion process followed by an additional annealing treatment. The CoFe2O4/2D-C composite comprises carbon coated spinel cobalt ferrite with densely connected porous layered structure facilitating fast electron and ion transport. Benefiting from such an inimitable structure, CoFe2O4/2D-C is employed as supercapacitors electrode material and exhibited a high specific capacitance (1318.1 Fg−1 at 2.5 A g−1 current density) and energy density (77.3 W h kg−1) with an excellent electrochemical capacity retention of 97.2 % after 4000 cycles. Power law which expresses the dependence of peak CV current on scan rate at fixed potential confirmed that, the charge storage mechanism for the electrode material (CoFe2O4/2D-C) is influenced congruently by both the capacitive and diffusive controlled process which promoted an efficient energy storage for CoFe2O4/2D-C. Accordingly, this outstanding performance put forward its application as an effective material for electrochemical capacitors.

Corn husk derived activated carbon with enhanced electrochemical performance for high-voltage supercapacitors

Porous carbons are considered as promising electrode materials for supercapacitors due to their excellent microstructural properties. Synthesizing porous carbon from a bio-waste material has received significant importance due to their natural abundance and low-cost. Here we report the synthesis of porous carbon from a bio-waste, sweet corn husk precursor. Influence of morphology and crystallinity of pre-activated carbon on the microstructural properties of the resultant activated carbons are studied. The chemical activation method results in carbon with turbostratic nature, high specific surface area (1370 m2 g-1) with large mesoporous volume fraction and 2D layered-like morphology. Similar specific surface area is observed for samples prepared with the variation in the amount of activating agent due to higher pre-carbonization temperature. The resultant activated carbon (ASCH-1:1) shows a specific capacitance of 127 F g−1 with low energy density (4.4 Wh kg−1) in 6 M KOH electrolyte. A high energy density of 20 Wh kg−1 is obtained in 1 M TEABF4/AN electrolyte with a high specific capacitance of 80 F g−1 at 1 A g−1. It shows good cyclic stability by retaining 90% of initial capacitance after 5000 cycles at 2 A g−1. Our results demonstrate that activated carbons reported here are promising materials for high operating voltage supercapacitors.

Multistage Self-Assembly Strategy: Designed Synthesis of N-doped Mesoporous Carbon with High and Controllable Pyridine N Content for Ultrahigh Surface-Area-Normalized Capacitance

Nitrogen doping could improve the performance of carbon materials in electrocatalysis, CO2 adsorption, and energy storage. [1]However, the control of the doping type and the amount of nitrogen (N)-...

RETRACTED: Ultra-fast one-step synthesis and surface engineering of mesoporous 3D α- Fe2O3 hollow nanospheres for high-performance and stable negative electrode for supercapacitors

Abstract Supercapacitors (SCs) have received considerable attention in portable digital devices because of their long life span and high power densities. However, low energy densities of SCs limited their practical applications due to the lack of high-performance negative electrode materials. This work demonstrates the surface engineering of α-Fe2O3 hollow nanospheres (α-Fe2O3-HNS) by controlled crystal growth through hollowing mechanism by the Ostwald ripening approach using facile one-step and low-cost hydrothermal method. The formation of α-Fe2O3-HNS was confirmed by scanning and transmission electron microscopy and further characterized by a variety of analytical methods. To investigate the electrochemical properties of α-Fe2O3-HNS, we systemically tested it in aqueous electrolyte under the extended potential window of −1.2–0.0 V versus Ag/AgCl. Among three samples of α-Fe2O3 nanospheres, the α-Fe2O3-HNS sample manifests a record high specific capacitance of 1041.18 F g−1 while partially hollow and solid α-Fe2O3 nanospheres displayed relatively low specific capacitances of 534.31 and 325.38 F g−1 at 1 A g−1, respectively. The α-Fe2O3-HNS sample demonstrates excellent cycling retention of 98.88% while other samples retained 94.23% and 88.25%, respectively after 10,000 cycles at a high current density of 15 A g−1. The surface engineering of α-Fe2O3-HNS offers not only the high surface area but also allows a large number of electroactive sites at electrode/electrolyte contact. Furthermore, we investigated the quantification of capacitive and diffusion controlled stored charge for high performance charge storage kinetics of as-prepared electrodes, by employing power’s law and impressively α-Fe2O3-HNS sample reveals high capacitive type charge storage of (85% at 10 mV/s). The obtainable results fully exhibit the unique advantage of a hollow structure to fabricate superior negative electrode materials for supercapacitors.

Defect engineered mesoporous 2D graphitic carbon nitride nanosheet photocatalyst for rhodamine B degradation under LED light illumination

In this work, a nitrogen vacancy induced 2D mesoporous graphitic carbon nitride (g-C3N4) nanosheet photocatalyst was successfully synthesized through a simple two-step thermal treatment method. The morphology of the nanosheet photocatalyst and the presence of nitrogen vacancy was explored through a wide range of characterization techniques. The as-prepared photocatalyst possess an improved visible light absorption efficiency as confirmed from the UV–vis diffuse reflectance spectroscopy (DRS). Moreover, the improved charge carrier separation efficiency of the nitrogen vacant material was demonstrated from the photoluminescence spectrum. Most importantly, the photocatalyst exhibited an excellent photodegradation efficiency towards rhodamine B (RhB) dye under the illumination of an 18 W LED light. The vacancy induced nanosheets demonstrated a degradation co-efficient of 0.074 min−1 in RhB degradation, which is 9.25 fold higher than that of the bulk g-C3N4. The nanosheets further exhibited an enhanced degradation efficiency toward tetracycline antibiotics. Furthermore, the photocatalyst displayed outstanding stability even after 5 cycles. A plausible photocatalytic mechanism has also been explained based on the results obtained from the radical scavenging experiments. This study would provide insight into the defect induction mechanism into the 2D g-C3N4 nanosheet and expected to help in rationally designing vacancy induced materials with cost-effective application in various environmental fields.

Boosting formate production at high current density from CO2 electroreduction on defect-rich hierarchical mesoporous Bi/Bi2O3 junction nanosheets

Electrocatalytic reduction of CO2 to formate is believed as one of the most technologically and economically viable strategies for valuable fuels and chemical productions. Defect-rich Bi/Bi2O3 nanosheets in situ grown on the carbon fiber papers (Bi/Bi2O3-CP) are directly used as an integrated cathode for CO2RR. Bi/Bi2O3-CP exhibits a high mass-normalized formate partial current density of 32.4 and 50.7 mA∙mg−1 cm−2 at −0.87 and −0.97 V, respectively, with high formate faradic efficiency of about 90 %. Incredibly, this cathode gives a record mass-normalized formate production rate of 1.12 mmol∙mg-1 cm-2 h-1 at −1.17 V, which exceeds drop-casted sample (0.41 mmol∙mg−1 cm−-2 h−1 at −1.17 V) and most state-of-the-art Bi based electrocatalysts. The boosted formation generation could be attributed to the unique mesoporous 3D hierarchical nanostructure with the integrated contributions of abundant defects and synergistic coordination of regionally disordered Bi/Bi2O3 metal/oxide junction.

Two-Dimensional Superstructures of Silica Cages.

Despite extensive studies on mesoporous silica since the early 1990s, the synthesis of two-dimensional (2D) silica nanostructures remains challenging. Here, mesoporous silica is synthesized at an interface between two immiscible solvents under conditions leading to the formation of 2D superstructures of silica cages, the thinnest mesoporous silica films synthesized to date. Orientational correlations between cage units increase with increasing layer number controlled via pH, while swelling with oil and mixed surfactants increase micelle size dispersity, leading to complex clathrate type structures in multilayer superstructures. The results suggest that a three-dimensional (3D) crystallographic registry within cage-like superstructures emerges as a result of the concerted 3D co-assembly of the organic and inorganic components. Mesoporous 2D superstructures can be fabricated over macroscopic film dimensions and stacked on top of each other. The realization of previously inaccessible mesoporous silica heterostructures with separation or catalytic properties unachievable via conventional bulk syntheses is envisioned.

A Molecular Foaming and Activation Strategy to Porous N-Doped Carbon Foams for Supercapacitors and CO2 Capture

HighlightsAn in situ molecular foaming and activation strategy is designed and investigated for the synthesis of hierarchically porous N-doped carbon foams (HPNCFs).The prepared HPNCFs possess 3D macropores, uniform micropores and mesopores, ultrahigh surface areas and high N contents and show high performances in supercapacitors and CO2 capture.

Mesoporous Metal-Metalloid Amorphous Alloys: The First Synthesis of Open 3D Mesoporous Ni-B Amorphous Alloy Spheres via a Dual Chemical Reduction Method.

Selective hydrogenation of nitriles is an industrially relevant synthetic route for the preparation of primary amines. Amorphous metal-boron alloys have a tunable, glass-like structure that generates a high concentration of unsaturated metal surface atoms that serve as active sites in hydrogenation reactions. Here, a method to create nanoparticles composed of mesoporous 3D networks of amorphous nickel-boron (Ni-B) alloy is reported. The hydrogenation of benzyl cyanide to β-phenylethylamine is used as a model reaction to assess catalytic performance. The mesoporous Ni-B alloy spheres have a turnover frequency value of 11.6 h-1 , which outperforms non-porous Ni-B spheres with the same composition. The bottom-up synthesis of mesoporous transition metal-metalloid alloys expands the possible reactions that these metal architectures can perform while simultaneously incorporating more Earth-abundant catalysts.

2D Mesoporous Channels of PMO; a Platform for Cluster-Like Pt Synthesis and Catalytic Activity in Nitrophenol Reduction

Thiourea-bridged organosiloxane is used to synthesize a periodic mesoporous organosilica (PMO). Since this PMO has an S-enriched surface, owing to thiourea functional groups, it exhibits strong coordination toward Pt ions, and it shows a high tunability in the Pt nanoparticles size. This hybrid mesoporous material is employed as a catalyst in the efficient reduction reaction of 4-nitrophenol to 4-aminophenol at room temperature in an aqueous media.

AgCoO2−Co3O4/CMC Cloudy Architecture as High Performance Electrodes for Asymmetric Supercapacitors

AbstractThis work represents the design of superior supercapacitor electrode that comprised of 3D cloud like silver cobalt oxide/cobalt oxide (AgCoO2−Co3O4) and carbon architecture. AgCoO2−Co3O4/C architecture can be fabricated from Co−Ag nitrate precursors with the addition of carboxymethyl cellulose followed by annealing. Mesoporous 3D cloudy architecture provides higher specific capacitance (575 F g−1 at a scan rate of 2 mV s−1) and rate performance (666 F g−1 at a current density of 1 A g−1). The combined effect of AgCoO2 embedded Co3O4 and carboxymethyl cellulose (carbon) highly favors for outstanding cycle life (around 1 % capacitance degradation even after 5000 cycles). Presence of such porous 3D architecture with carbon backbone delivers admirable energy/power density. Also, an advanced asymmetric supercapacitor with an operating range of 1.2 V is designed by utilizing this porous 3D cloudy architecture as positive electrode and activated carbon as negative electrode. The fabricated design shows a robust energy density of 17 W h kg−1 with a high power density of 166 W kg−1 at a current density of 1 A g−1. The findings of the current study underline the potential of AgCoO2−Co3O4/C electrodes for supercapacitor applications.

Exfoliated Mesoporous 2D Covalent Organic Frameworks for High-Rate Electrochemical Double-Layer Capacitors.

The electrochemical double-layer capacitors (EDLCs) are highly demanded electrical energy storage devices due to their high power density with thousands of cycle life compared with pseudocapacitors and batteries. Herein, a series of capacitor cells composed of exfoliated mesoporous 2D covalent organic frameworks (e-COFs) that are able to perform excellent double-layer charge storage is reported. The selected mesoporous 2D COFs possess eclipsed AA layer-stacking mode with 3.4 nm square-like open channels, favorable BET surface areas (up to 1170 m2 g-1 ), and high thermal and chemical stabilities. The COFs via the facile, scalable, and mild chemical exfoliation method are further exfoliated to produce thin-layer structure with average thickness of about 22 nm. The e-COF-based capacitor cells achieve high areal capacitance (5.46 mF cm-2 at 1,000 mV s-1 ), high gravimetric power (55 kW kg-1 ), and relatively low τ0 value (121 ms). More importantly, they perform nearly an ideal DL charge storage at high charge-discharge rate (up to 30 000 mV s-1 ) and maintain almost 100% capacitance stability even after 10 000 cycles. This study thus provides insights into the potential utilization of COF materials for EDLCs.