Hollow Mesoporous Carbon Spheres Research Articles

Engineering hollow metal ion-phenolic capsules and metal-doped hollow mesoporous carbon spheres with “full green” style

Hollow metal ion-phenolic capsules (HMPCs) were synthesized through the combination of chelation with multiple hydrogen bonding that derive from the interaction of tannic acid (TA) and Pluronic F127. In this strategy, TA, a renewable and natural polyphenol, plays main role in the whole reaction process: a) create the “TA/F127 emulsion” driven by the multiple hydrogen bonding; b) construct the skeleton of HMPCs via the coordination with CuⅡ. Furthermore, we expanded this advanced concept into the fabrication of metal-doped hollow mesoporous carbon spheres (MHMCSs) elegantly and obtained Cu-Fe co-doped hollow mesoporous carbon spheres with 3.9 nm pore size and high specific surface area (365 m2/g). Compared to existing technology, the redundant treatments (e.g. hydrothermal treatment, sacrificial template removal and quite long reaction time) and toxic raw materials (e.g. formaldehyde, resorcinol) have been abandoned. Full green concept throughout the whole synthesis process presents an elegant paradigm for the preparation of HMPCs and MHMCSs.

Pd–Cu Alloy Nanoparticles Confined within Mesoporous Hollow Carbon Spheres for the Hydrogenation of CO2 to Formate

It is intriguing yet challenging to synthesize high-performance heterogeneous catalysts for carbon dioxide (CO2) hydrogenation reactions. The excellent catalytic performance of heterogeneous cataly...

The extraction of four endocrine disrupters using hollow N-doped mesoporous carbon spheres with encapsulated magnetite (Fe3O4) nanoparticles coupled to HPLC-DAD determination

Magnetite/hollow core–shell N-doped mesoporous carbon sphere (Fe3O4/N-HCSCs) composites were prepared as a sorbent for ultrasound-assisted magnetic solid-phase extraction of four endocrine disrupter compounds (EDCs) from water samples prior to the EDCs determination by high-performance liquid chromatography with a diode array detector (HPLC-DAD) (analytical wavelength, 260 nm). The Fe3O4/N-HCSCs, which contained N-HCSCs with encapsulated magnetite nanoparticles, were also characterized. The extraction and elution conditions were optimized by a one-factor-at-a-time approach using prepared Fe3O4/N-HCSCs for the selected the EDCs (triclosan, triclocarban, bisphenol A, and tetrabromobisphenol A bis(allyl)ether). Under the optimum extraction/elution conditions, the previously mentioned procedure achieved low detection limits (0.05–0.1 μg·L−1), high recovery values (88.0%–97.0%), satisfactory preconcentration factors (115–136), and good reproducibility (relative standard deviations of less than 5.8%, n = 4). Kinetic and isotherm studies showed that the adsorption process followed pseudo-second-order kinetic and Freundlich equilibrium models. The Fe3O4/N-HCSCs had a good selectivity for the selected EDCs, mainly due to the large specific surface area of the sorbent, the presence of nitrogen species on the sorbent, and the hydrophobic interaction between the EDCs and sorbent. This work revealed the potential value of the method for rapidly screening EDCs in environmental water samples.

Insight into the performance and stability of N-doped Ordered Mesoporous Carbon Hollow Spheres for the ORR: Influence of the nitrogen species on their catalytic activity after ADT

Novel N-doped Ordered Mesoporous Carbon Hollow Spheres (N-OMCHS) were successfully synthetized using two different nitrogen sources: i) 2-pyridinecarboxaldehyde (labeled as N1-OMCHS), and ii) pyrrole (labeled as N2-OMCHS). The catalytic activity of the synthesized N-OMCHS was evaluated towards the Oxygen Reduction Reaction (ORR) in alkaline media. Likewise, the effect of Accelerated Degradation Test (ADT) on the stability of the N-OMCHS was discussed. N2-OMCHS showed the best performance for the ORR (Eonset = 0.88 V, E½ = 0.82 V, H2O2 yield = 3.8% and n = 3.92, all potentials vs. RHE). Surprisingly, after evaluating the stability of each electrocatalyst by ADT, it was observed that the performance of N1-OCMHS improved with respect to that evaluated before ADT. N1-OCMHS had a better stability compared to N2-OMCHS. X-ray photoelectron spectroscopy (XPS) results before and after ADT demonstrated the chemical modification of nitrogen species on the surface of the electrocatalysts, which influenced a better performance towards the ORR. Therefore, N-OMCHS were considered as potential non-platinum electrocatalysts for Anion Exchange Membrane Fuel Cells (AEMFC) cathode applications.

Synthesis of multiple Ag nanoparticles loaded hollow mesoporous carbon spheres for highly efficient and recyclable catalysis

Multiple Ag nanoparticles loaded hollow mesoporous carbon spheres ([email protected]) are successfully synthesized through a “soft-to-hard templating” approach. In this method, polyacrylic acid (PAA) colloids are used as stabilizers for Ag nanoparticles and serve as soft templates for a sol-gel process with tetraethyl orthosilicate and polymerization process of resorcinol-formaldehyde resin (RF resin) in one pot. [email protected] are obtained after carbonization of the RF resin layer and selectively etching the SiO2 component. [email protected] exhibit a spherical morphology with a mean size of approximately 140 nm and a high surface area of 239.67 m2 g−1, and the average size of encapsulated silver nanoparticles are about 10 nm without aggregation. The prepared [email protected] show excellent catalytic activity and stability for reduction of 4-nitrophenol, Congo red, and Rhodamine B. Therefore, this “soft-to-hard templating” approach represents a promising strategy for the preparation of high-performance carbon nanoparticle-supported catalysts.

Favorable anion adsorption/desorption of high rate NiSe2 nanosheets/hollow mesoporous carbon for battery-supercapacitor hybrid devices

High-rate battery-type cathode materials have attracted wide attention for advanced battery-supercapacitor hybrid (BSH) devices. Herein, a core-shell structure of the hollow mesoporous carbon spheres (HMCS) supported NiSe2 nanosheets (HMCS/NiSe2) is constructed through two-step reactions. The HMCS/NiSe2 shows a max specific capacity of 1,153.5 C·g−1 at the current density of 1 A·g−1, and can remain at 774.5 C·g−1 even at 40 A·g−1 (the retention rate as high as 67.1%) and then the HMCS/NiSe2 electrode can keep 80.5% specific capacity after 5,000 cycles at a current density of 10 A·g−1. Moreover, the density functional theory (DFT) calculation confirmed that the introduction HMCS into NiSe2 made adsorption/desorption of OH− easier, which can achieve higher rate capability. The HMCS/NiSe2//6 M KOH//HMCS hybrid device has energy density of 47.15 Wh·kg−1 and power density of 801.8 W·kg−1. This work provides a feasible electrode material with a high rate and its preparation method for high energy density and power density energy storage devices.

Surface Functionalization of Ordered Mesoporous Hollow Carbon Spheres with Ru Organometallic Compounds as Supports of Low-Pt Content Nanocatalysts for Alkaline Hydrogen and Oxygen Evolution Reactions

AbstractHerein, we report a methodology that leads to the formation of Ru metallic sites, followed by the development and anchorage of Pt-Ru alloyed nanoparticles on the surface of Ordered Mesoporous Hollow Carbon Spheres (OMHCS). Along with the Ru sites, it is demonstrated that the functionalization promotes the formation of functional groups on the surface of the OMHCS. In a first stage, OMHCS are functionalized with the [(η6-C6H5OCH2CH2OH)RuCl2]2 (Ru-dim) and [(η6-C6H4CH(CH3)2CH3)RuCl2]2 (Ru-cym) organometallic compounds. Afterwards, Pt nanoparticles are dispersed by the microwave-assisted polyol method over the functionalized supports obtaining the low-metal content 5 wt. % Pt/OMHCSRu-dim and Pt/OMHCSRu-cym nanocatalysts. The degree of Ru alloyed is found to be around 35%. The low-Pt content Pt/OMHCSRu-cym and Pt/OMHCSRu-dim exhibit a higher catalytic activity for the Oxygen (OER) and the Hydrogen (HER) Evolution Reactions than the Pt/C benchmark and the Pt/OMHCS nanocatalysts. The overpotential for the OER at 10 mA cm-2 (ηOER) is 300 mV and 210 mV smaller at Pt/OMHCSRu-cym and Pt/OMHCSRu-dim compared to Pt/C, respectively. The corresponding values of the HER at -10 mA cm-2 (ηHER) are 14 and 18 mV smaller, respectively. The high catalytic activity of Pt/OMHCSRu-cym and Pt/OMHCSRu-dim has been attributed in part to the presence of Ru0 and RuO2 species from organometallic functionalization, and the modification of the d-valence band of Pt. Their high performance for the OER and the HER opens new lines of research for the design of nanocatalysts for alkaline electrochemical water splitting.

Preparation of hollow mesoporous carbon spheres by pyrolysis-deposition using surfactant as carbon precursor

Hollow mesoporous carbon spheres (HCS) are widely used in many fields, such as supercapacitors, adsorption, separation, batteries, etc., due to their large specific surface area, large cavity, thin mesoporous shell and good chemical stability. Herein, N-doped HCS was prepared using the pyrolysis-deposition method, with cetyltrimethylammonium bromide (CTAB) micelles derived from a hard template of solid silica core coated with mesoporous silica (SiO2@mSiO2), as the carbon and nitrogen precursor. This method realizes direct carbon formation from the decomposable surfactant CTAB, which avoids the need for other carbon precursors and simplifies the preparation process. The mesopores on the SiO2@mSiO2 template shell provide limited space and the transition metals provide active sites, which promotes the deposition of carbon derived from surfactants.The shell thickness of HCS can be adjusted by the thickness of the SiO2@mSiO2 template shell, which leads to a change in the morphology, i.e. from imperfect (macropore) hollow spheres to complete hollow spheres and transformation of the surface from rough to smooth. Ultimately, the resultant HCS completely replicates the morphology of the template and shows a uniform spherical shape with a mesoporous shell, a cavity, a high specific surface area and suitable N-doping content, which ensures good electrochemical performance as an active electrode material in supercapacitors.

Li+ storage properties of SiO2@C core-shell submicrosphere and its hollow counterpart synthesized by molecular self-assembly in wet-chemistry condition as anodes for LIBs

SiO2@C core-shell submicrospheres (SiO2@C) were fabricated via molecular self-assembly process in wet-chemistry condition and followed by post-calcination. SEM and TEM indicated the outer diameter of SiO2@C is ∼300–400 nm. The diameter of inner SiO2 core can be controlled from maximum size to zero by NaOH solution etching. XRD, TG-DSC, BET, Raman and XPS were adopted to reveal its microstructure and elemental composition. Systematic electrochemical tests manifested that the specific capacity of SiO2@C reduces at the beginning then increases with the decrease of SiO2 core diameter. The underlying Li+ storage mechanism is discussed and analyzed, which illustrates that the effective utilization of active sites is the key for electrochemical performance when SiO2@C used as anode material for LIBs. And the completely etched hollow mesoporous carbon sphere without SiO2 core (HMCS, SiO2@C-12 h) exhibited the highest capacity and rate capability (349.2 mA h/g at 100 mA/g after 200 cycles; 316.0 mA h/g at 400 mA/g), which is due to the effective Li+ active sites benefitted from its conductive and porous carbon network.

Electrocatalytic Reduction Catalysts: Hollow Mesoporous Carbon Sphere Loaded Ni–N4 Single‐Atom: Support Structure Study for CO2 Electrocatalytic Reduction Catalyst (Small 41/2020)

Electrocatalytic Reduction Catalysts: Hollow Mesoporous Carbon Sphere Loaded Ni–N₄ Single‐Atom: Support Structure Study for CO₂ Electrocatalytic Reduction Catalyst (Small 41/2020)

Space‐Confined Yolk‐Shell Construction of Fe3O4 Nanoparticles Inside N‐Doped Hollow Mesoporous Carbon Spheres as Bifunctional Electrocatalysts for Long‐Term Rechargeable Zinc–Air Batteries

AbstractDevelopment of efficient, durable and inexpensive oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) electrocatalysts with accelerated kinetics and high‐performance remain a grand challenge in the context of reversible metal–air batteries. Herein, the Fe3O4 nanoparticles inside N‐doped hollow mesoporous carbon spheres (N/HCSs) yolk‐shell structure (Fex@N/HCSs) is constructed as an excellent bifunctional electrocatalyst for ORR and OER via an innovative approach. The N/HCSs effectively control and confine in situ growth of Fe3O4 nanoparticles using the melting‐diffusion strategy via capillary force and significantly improve the conductivity and structural stability of the hybrid material. The constructed yolk‐shell structured Fe20@N/HCSs ecosystem with Fe–Nx active sites exhibits excellent ORR and OER activity and stability, which even surpass commercial grade Pt/C, RuO2, IrO2 and many reported catalysts. Moreover, the zinc–air battery assembled with Fe20@N/HCSs as a cathode achieves high open circuit voltage (1.57 V), large power density (140.8 mW cm−2), and excellent long‐term cycling performance (over 300 h), revealing superior performance compared to commercial Pt/C + RuO2. This work provides a new avenue for the design and optimization of other high‐performance yolk‐shell materials with nanoscale confinement structures.

Ni2P nanosheets modified N-doped hollow carbon spheres towards enhanced supercapacitor performance

Carbon materials have been attracted attention because of high supercapacitor activity. In this work, N-doped mesoporous hollow carbon spheres coated with Ni2P nanosheets are prepared by hydrothermal and calcination processes using a SiO2 template. N element doping changes the structure of hollow carbon spheres. Ni2P nanosheets are grown uniformly on the surface of the N-doped carbon spheres (N-CS). Due to the unique atomic arrangement of N-CS, the hollow mesoporous structure, and coupling with the unique composition of Ni2P nanosheets, N–C@Ni2P composites exhibit excellent electrochemical performance as supercapacitor electrodes with high specific capacitance and cycle stability under high current density. When the current density is 10 A g−1, the specific capacitance is 1320.4 F g−1. The capacitance retention rate after 1500 cycles is 76%. In the case of a current density of 20 A g−1, the specific capacitance is still up to 1062 F g−1. This method provides a fine strategy for designing high-performance supercapacitors based on carbon materials.

Hollow Mesoporous Carbon Sphere Loaded Ni-N4 Single-Atom: Support Structure Study for CO2 Electrocatalytic Reduction Catalyst.

Single-atom catalysts have become a hot spot because of the high atom utilization efficiency and excellent activity. However, the effect of the support structure in the single-atom catalyst is often unnoticed in the catalytic process. Herein, a series of carbon spheres supported Ni-N4 single-atom catalysts with different support structures are successfully synthesized by the fine adjustment of synthetic conditions. The hollow mesoporous carbon spheres supported Ni-N4 catalyst (Ni/HMCS-3-800) exhibits superior catalytic activity toward the electrocatalytic CO2 reduction reaction (CO2 RR). The Faradaic efficiency toward CO is high to 95% at the potential range from -0.7 to -1.1V versus reversible hydrogen electrode and the turnover frequency value is high up to 15 608 h-1 . More importantly, the effect of the geometrical structures of carbon support on the CO2 RR performance is studied intensively. The shell thickness and compactness of carbon spheres regulate the chemical environment of the doped-N species in the carbon skeleton effectively and promote CO2 molecule activation. Additionally, the optimized mesopore size is beneficial to improve diffusion and overflow of the substance, which enhances the CO2 adsorption capacity greatly. This work provides a new consideration for promoting the catalytic performance of single-atom catalysts.

Ultrasmall SnO2 nanocrystals with adjustable density embedded in N-doped hollow mesoporous carbon spheres as anode for Li+/Na+ batteries

SnO2 has been widely studied in lithium-ion batteries (LIBs) because of its high theoretical specific capacity and reversible alloying reaction. Herein, we reported a novel strategy of confinement growth to implant nano-sized SnO2 crystals into N-doped hollow mesoporous carbon spheres (NHMCS) to form SnO2@NHMCS composite with unique nanoscale voids. The nanocrystals (~ 5 nm) decrease the required activation energy for redox reactions, and the carbon shell of NHMCS improves the conductivity and structural stability. It is worth noting that this method can effectively control the filling degree of ultrasmall nanocrystals in NHMCS and adjust the nanosize of voids between nanocrystals and NHMCS. When SnO2@NHMCS is evaluated as an anode material for LIBs, it is proved to exhibit high reversible capacity and stable cycling performance, which is attributted to the appropriate content of active components and the ample buffer space for conversion reaction of SnO2 and alloying reaction of Sn. It also shows excellent electrochemical property as anode material for sodium-ion batteries.

Mesoporous Carbon Hollow Spheres as Efficient Electrocatalysts for Oxygen Reduction to Hydrogen Peroxide in Neutral Electrolytes

Hydrogen peroxide is a widely used and important chemical in industry. A two-electron electrochemical oxygen reduction reaction (2e– ORR) is a clean and on-site method for H2O2 production. Here, we...

Stable yolk-structured catalysts towards aqueous levulinic acid hydrogenation within a single Ru nanoparticle anchored inside the mesoporous shell of hollow carbon spheres

To well address the problem of low stability for Ru-based catalysts against sintering and leaching during synthesis and aqueous levulinic acid (LA) hydrogenation to γ-valerolactone (GVL), herein we demonstrate an “inside-to-outside” synthetic strategy for robust yolk-structured nanospheres within a single Ru nanoparticle (NP, 4.2 nm) anchored inside the mesoporous shell (pore size, 4.0 nm), denoted as YS Ru@HMCS (yolk-structured Ru encapsulated into hollow mesoporous carbon sphere). Such a shell-supported-core configuration combines the merits of conventional yolk-structured and supported types, in which the active core is not only fully exposed, but also strongly anchored on the shell, based on the optimized interaction between oxidized Ru NP and N-doped mesoporous carbon shell. As a consequence, the resultant YS Ru@HMCS, delivers a high LA conversion (99.4%), a large selectivity to GVL (99.9%), and prolonged cycling life (up to 9 cycles) under water towards the LA hydrogenation, that exceeds conventional yolk-structured and supported analogues. Sintering-resistant, a single Ru NP is successfully encapsulated, and its leaching-resistant property is enhanced based on the improved metal-support contact, thus affording a highly stable Ru catalyst. Moreover, such a synthetic concept can be extended to the stabilization of other supported catalysts, providing a general approach to enhancing both the thermal and chemical stability of supported nanocatalysts.

Rational design of MoS2 nanosheets decorated on mesoporous hollow carbon spheres as a dual-functional accelerator in sulfur cathode for advanced pouch-type Li–S batteries

Abstract Developing sulfur cathodes with high catalytic activity on accelerating the sluggish redox kinetics of lithium polysulfides (LiPSs) and unveiling their mechanisms are pivotal for advanced lithium–sulfur (Li–S) batteries. Herein, MoS2 is verified to reduce the Gibbs free energy for rate-limiting step of sulfur reduction and the dissociation energy of lithium sulfide (Li2S) for the first time employing theoretical calculations. The MoS2 nanosheets coated on mesoporous hollow carbon spheres (MHCS) are then reasonably designed as a sulfur host for high-capacity and long-life Li–S battery, in which MHCS can guarantee the high sulfur loading and fast electron/ion transfer. It is revealed that the shuttle effect is efficiently inhibited because of the boosted conversion of LiPSs. As a result, the coin cell based on the MHCS@MoS2-S cathode exhibits stable cycling performance maintaining 735.7 mAh g−1 after 500 cycles at 1.0 C. More importantly, the pouch cell employing the MHCS@MoS2-S cathodes achieves high specific capacity of 1353.2 mAh g−1 and prominent cycle stability that remaining 960.0 mAh g−1 with extraordinary capacity retention of 79.8% at 0.1 C after 170 cycles. Therefore, this work paves a new avenue for developing practical high specific energy and long-life pouch-type Li–S batteries.

Modulating the Void Space of Nitrogen‐Doped Hollow Mesoporous Carbon Spheres for Lithium‐Sulfur Batteries

AbstractHollow carbon materials have been extensively investigated as sulfur hosts for lithium‐sulfur batteries. Herein, we report a designed synthesis of nitrogen‐doped mesoporous hollow carbon spheres with tunable void spaces through an ethylenediamine‐assisted cooperative self‐assembly strategy between 3‐aminophenol/formaldehyde resin and silica. Nitrogen‐doped hollow mesoporous carbon spheres (NHMCS) with an optimised inside/outside radius ratio of 0.52 have induced improved electrochemical performances compared to other NHMCS, demonstrating a fine material design strategy for electrochemical energy storage systems with improved performance.

Fluorescent hollow mesoporous carbon spheres for drug loading and tumor treatment through 980-nm laser and microwave co-irradiation

Hollow mesoporous particles for drug delivery and cancer therapy have attracted significant attention over recent decades. Here, we develop a simple and highly efficient strategy for preparing fluorescent hollow mesoporous carbon spheres (HMCSs). Compared with typical carbon materials such as fullerene C60, carbon nanotubes, reduced graphene oxide, and carbon nanohorns; HMCSs showed fewer effects on cell cycle distribution and lower toxicity to cells. Ten different drugs were incorporated into the HMCSs, and the maximum loading efficiency reached 42.79 ± 2.7%. Importantly, microwaves were found to improve the photothermal effect generated by HMCSs when combined with 980-nm laser irradiation. The cell killing and tumor growth inhibition efficiencies of HMCSs and drug-loaded HMCSs under co-irradiation with laser and microwaves were significantly improved compared with those under laser irradiation alone. After local administration HMCSs were only distributed in tissue at the injection site. HMCSs showed almost no toxicity in mice after local injection and could be completely removed from the injection site.

A new graphitic carbon nitride-coated dual Core–Shell sulfur cathode for highly stable lithium–sulfur cells

Lithium-sulfur (Li–S) batteries have promise to deliver energy density two to three times higher than that of currently used lithium-ion batteries. The commercialization of Li–S batteries is primarily hindered due to the polysulfide shuttle (PSS) effect, which not only leads to the loss of active materials from the cathode, but also causes serious irreversible reactions between the polysulfide intermediates and the lithium metal anode, resulting in low coulombic efficiency, high self-discharge and short cycle life. In this paper, we report the design and synthesis of a new graphitic carbon nitride-coated dual core–shell structured sulfur cathode (S@HCS@g-C3N4) to address these issues, leading to superior capacity retention properties in Li–S cells. This structural design allows confinement of polysulfide intermediates within a dual-core electrically conductive structure consisting of a hollow mesoporous carbon sphere (HCS) core, and a peripheral graphitic carbon nitride (g-C3N4) layer, which is known to suppress the PSS effect by enhanced chemical interactions with polysulfide intermediates. Indeed, the S@HCS@g-C3N4 cathode displayed excellent electrochemical performance in terms of high initial specific capacity (1446 mA h g−1 at 0.2C) and very good long-term cycling performance (capacity decay rate of 0.049% per cycle after 500 cycles at 1C).