Nitrogen-doped Hollow Mesoporous Carbon Research Articles

Nitrogen-doped hollow mesoporous carbon spheres for efficient oxygen reduction

Extensive investigations have been devoted to nitrogen-doped carbon materials as catalysts for the oxygen reduction reaction (ORR) in various conversion technologies. In this study, we introduce nitrogen-doped carbon materials with hollow spherical structures. These materials demonstrate significant potential in ORR activity within alkaline media, showing a half-wave potential of 0.87 V versus the reversible hydrogen electrode (RHE). Nitrogen-doped hollow carbon spheres (N-CHS) exhibit unique characteristics such as a thin carbon shell layer, hollow structure, large surface area, and distinct pore features. These features collectively create an optimal environment for facilitating the diffusion of reactants, thereby enhancing the exposure of active sites and improving catalytic performance. Building upon the promising qualities of N-CHS as a catalyst support, we employ heme chloride (1 wt%) as the source of iron for Fe doping. Through the carbonization process, Fe-N active sites are effectively formed, displaying a half-wave potential of 0.9 V versus RHE. Notably, when implemented as a cathode catalyst in zinc-air batteries, this catalyst exhibits an impressive power density of 162.6 mW cm−2.

2H-MoS 2 Modified Nitrogen-Doped Hollow Mesoporous Carbon Spheres as the Efficient Catalytic Cathode Catalyst for Aprotic Lithium-Oxygen Batteries

2H-MoS ₂ Modified Nitrogen-Doped Hollow Mesoporous Carbon Spheres as the Efficient Catalytic Cathode Catalyst for Aprotic Lithium-Oxygen Batteries

Nitrogen-doped 3D hollow carbon spheres for efficient selective oxidation of C–H bonds under mild conditions

Nitrogen-doped hollow mesoporous carbon spheres present excellent conversion and selectivity in the selective oxidation of ethylbenzene at 50 °C.

Highly efficient tungsten-doped hierarchical structural N-Enriched porous carbon counter electrode material for dye-sensitized solar cells

In this study, a novel hierarchical hybrid of tungsten species nanoparticles anchored on nitrogen-doped hollow mesoporous carbon (WC/N-HHMC) with high surface area and hierarchical porosity is synthesized and investigated as a noble metal-free counter electrode (CE) for dye-sensitized solar cells (DSSCs). The unique characteristics such as co-doping of graphitic nitrogen and tungsten species nanoparticles, high specific surface area, and interconnected hierarchical porosity render WC(0.7)/N-HHMC an alternative of Pt-based CE for DSSCs. The tungsten species serve as high electrocatalytic activity centers providing available active sites for regeneration of I−/I3− electrolyte, while N-HHMC endows a high-speed transport pathway to facilitate the electron transfer from carbon skeleton to active sites. Electrochemical investigations indicate that WC(0.7)/N-HHMC electrode displays excellent electrocatalytic activity for I3− reduction due to lower charge-transfer resistance (RCT) at CE/electrolyte interface. Benefiting from the above advantages, a DSSC based on WC(0.7)/N-HHMC CE shows an energy conversion efficiency of 8.0%, which is superior to that of cell assembled with platinized CE (7.8%). More remarkably, WC(0.7)/N-HHMC exhibits a good electrochemical stability toward I−/I3− redox reaction. The present study demonstrates the rationality for preparation of inexpensive WC(0.7)/N-HHMC electrocatalyst with special structures and its application as a great alternative to Pt-based CE for DSSCs.

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.

Confined-Space Pyrolysis of Polystyrene/Polyacrylonitrile for Nitrogen-Doped Hollow Mesoporous Carbon Spheres with High Supercapacitor Performance

Nitrogen-doped hollow mesoporous carbon spheres have drawn much attention in many applications, including adsorption, catalysis and energy storage, etc. because of their hollow structure, thin carb...

Nitrogen-Doped Hollow Mesoporous Carbon Spheres Modified g-C3N4/Bi2O3 Direct Dual Semiconductor Photocatalytic System with Enhanced Antibiotics Degradation under Visible Light

Herein, the nitrogen-doped hollow mesoporous carbon spheres (N-HMCs) modified g-C3N4/Bi2O3 direct dual semiconductor photocatalyst (g-C3N4/Bi2O3@N-HMCs) were synthesized by a facile thermal process. The morphology, structure, elements, and photoelectrochemical properties of the as-prepared samples were characterized by electron microscopy, N2 sorption–desorption, X-ray diffraction, X-ray photoelectron spectroscopy, diffuse-reflectance spectra, and photoluminescence spectroscopy, among other technologies. The photocatalytic efficiency was evaluated toward degradation of antibiotics tetracycline hydrochloride (TCH) and ciprofloxacin hydrochloride (CFH) under visible-light irradiation, and the results showed that the g-C3N4/Bi2O3@N-HMCs composite exhibited superior photocatalytic efficiency than other comparison samples, which could be attributed to the synergistic action of g-C3N4/Bi2O3 direct dual semiconductor photocatalytic system and the N-HMCs. The characterization techniques revealed that N-HMCs play ...

Nitrogen-Doped Hollow Mesoporous Carbon Spheres for Efficient Water Desalination by Capacitive Deionization

Water desalination performance of capacitive deionization (CDI) largely depends on electrode materials properties. Rational design and regulation of the structure and composition of electrode materials to acquire high CDI performance is of great significance. Herein, nitrogen-doped hollow mesoporous carbon spheres (N-HMCSs) were investigated as electrode material for CDI application. To understand the effect of structure and composition on CDI performance, another two CDI electrode materials, i.e., hollow mesoporous carbon spheres (HMCSs) and solid mesoporous carbon spheres (SMCSs) were prepared for comparison. The obtained N-HMCSs possessed unique hollow cavity and excellent nitrogen doping property, resulting in fast ion diffusion, good charge transfers ability and fine wettability. Compared with HMCSs and SMCSs electrodes, N-HMCSs electrode exhibited an improved electrosorption capacity and rate, demonstrating the dependence of CDI performance on the synergistic effect of hollow structure and nitrogen ...

Silica-Assisted Assembly for Synthesis of Nitrogen-Doped Hollow Mesoporous Carbon Spheres as Supercapacitors

Nitrogen-doped hollow mesoporous carbon spheres (NHMCSs) are synthesized by a one-pot silica-assisted assembly process and applied in supercapacitors. SiO2 spheres act as interior cores, which is crucial to form the hollow structure. 3-Aminophenol/formaldehyde resin and tetraethylorthosilicate (TEOS) cross-link through hydroxyl groups, then together directly deposit and co-assemble with cetyltrimethylammonium bromide via electrostatic interactions leading to an outer carbon-silica shell surrounding the SiO2 spheres. In the preparing process, TEOS not only acts as silica-assisted material and assembles with 3-aminophenol/formaldehyde resin, but also creates more pores to improve the surface area. After carbonization and silica etching, the NHMCSs with spherical morphology, uniform mesoporous, hollow structure, high surface area and nitrogen content are obtained. The nitrogen-doped, hollow and mesoporous structure are conducive to improve the capacitance. As electrode materials, the NHMCSs exhibit a high capacitance (201 F g−1 at 1 A g−1) and a good cycling stability (83.3% after 5000 cycles). These results reveal that NHMCSs can be expected to be promising electrode materials for electrochemical capacitors.

Nitrogen-doped hollow mesoporous carbon spheres as a highly active and stable metal-free electrocatalyst for oxygen reduction

Nitrogen-doped hollow mesoporous carbon spheres (NHCSs) were successfully prepared via a simple, scalable hydrothermal method, followed by thermal treatment at 650 °C in ammonia atmosphere and subsequent high temperature annealing at 800–1000 °C in nitrogen, respectively. The resulting NHCSs with a particle diameter of ∼150 nm and a shell thickness of ∼20–25 nm have high specific surface areas (738–820 m2 g−1), large pore volume (0.50–0.56 cm3 g−1), bimodal pores system (3.9 and 51.6 nm) and adjustable N-doping levels (3.6–7.8 at.%) depending on the pyrolysis temperature. The unique structure of hollow spheres for NHCSs with uniform mesopores throughout the shells can both promote fast mass transfer and provide inner and outer surfaces with high density of N-related active sites, thus improving the reaction kinetics. The NHCS-1000 (annealed at 1000 °C) exhibited not only comparable ORR activity with a direct four-electron reaction pathway in terms of onset and half-wave potentials, and limiting current densities, but superior long-term durability and methanol-tolerance to commercial Pt/C catalyst, because it has the highest relative content of graphitic-N and pyridinic-N groups, indicating their crucial roles in ORR. The NHCS-1000 with excellent ORR performance is of potential to replace Pt/C catalyst for ORR in practical applications.

Controllable synthesis of nitrogen-doped hollow mesoporous carbon spheres using ionic liquids as template for supercapacitors

We have demonstrated a facile and controllable synthesis of monodispersed nitrogen-doped hollow mesoporous carbon spheres (N-HMCSs) using resorcinol/formaldehyde resin as a carbon precursor, tetraethyl orthosilicate as a structure-assistant agent, ionic liquids (ILs) as soft template, partial carbon sources, and nitrogen sources. The sizes and the architectures including hollow and yolk-shell of resultant carbon spheres can be efficiently controlled through the adjustment of the content of ILs. Alkyl chain length of the ILs also has an important effect on the formation of N-HMCSs. With proper alkyl chain length and content of ILs, the resultant N-HMCSs show monodispersed hollow spheres with high surface areas (up to 1158m2g−1), large pore volumes (up to 1.70cm3g−1), and uniform mesopore size (5.0nm). Combining the hollow mesoporous structure, high porosity, large surface area, and nitrogen functionality, the as-synthesized N-HMCSs have good supercapacitor performance with good capacitance (up to 159Fg−1) and favorable capacitance retention (88% capacitive retention after 5000 cycles).

Nitrogen-doped hollow carbon spheres for supercapacitors application

Highly monodispersed nitrogen-doped hollow mesoporous carbon spheres (N-HMCSs) are prepared through a “silica-assisted” synthetic strategy with cetyltrimethylammonium bromide as cationic surfactant, 3-aminophenol/formaldehyde as carbon and nitrogen sources, tetraethyl orthosilicate as the structure-assistant agent. The particle sizes and shell thicknesses of the N-HMCSs can be easily tuned in the range of 130–290 nm and 17–42 nm, respectively, by simply modifying the ethanol-water volume ratio. The obtained N-HMCSs have high surface areas (750–1006 m2 g−1), large pore volumes (1.01–1.41 cm3 g−1), uniform mesoporous size of ∼3 nm, and high nitrogen loading content of 6.86 wt%. Due to these characteristics, the N-HMCSs exhibit a specific capacitance of 170 F g−1 at a current density of 1.0 A g−1 in 6 M KOH aqueous electrolyte. Besides, the capacitance still remains 94% after 5000 charge/discharge cycle, suggesting excellent cycling stability. The N-HMCSs may show promising prospects as electrode materials for electrochemical capacitors.

“Dissolution-Capture” Strategy to Form Monodispersed Nitrogen-Doped Hollow Mesoporous Carbon Spheres

Monodispersed nitrogen-doped hollow mesoporous carbon spheres (N-HMCSs) have been successfully synthesized using a novel “dissolution-capture” method. The mesoporous silica is uniformly coated on the surface of the polystyrene/polyacrylonitrile composite nanospheres (PS@PAN) core by using a modified Stöber method. Then a hollow cavity is formed through the dissolution of the PS@PAN in organic solvent. The dissolved PS@PAN as the carbon and nitrogen precursor is captured in the mesochannels of the silica shell. The obtained N-HMCSs have high specific surface area of 807 m2 g−1, uniform mesopore size of 4.1 nm, and nitrogen content of 3.6 at.%. In addition, the N-HMCSs show a high specific capacitance of 212 F g−1 at a current density of 1 A g−1 in 6 M KOH electrolyte and capacitance retention of 93.9% after 10000 charge/discharge cycles at 5 A g−1. The “dissolution-capture” method can give a useful enlightenment for the design of electrode materials for supercapacitors.

Spherical nitrogen-doped hollow mesoporous carbon as an efficient bifunctional electrocatalyst for Zn-air batteries.

Materials based upon porous carbon have gained considerable attention due to their high surface area, electric conductivity, thermal and chemical stability, low density, and availability. These superior properties make them ideal for diverse applications. Doping these carbon nanostructures holds promise of designing the properties of these structures and opening the door to practical applications. Herein, we report the preparation of hollow N-doped mesoporous carbon (HMC) spheres fabricated via polymerization and carbonization of dopamine on a sacrificial spherical SiO(2) template that is removed upon hydrofluoric acid etching. The morphology and structural features of these HMCs were evaluated using scanning electron microscopy and transmission electron microscopy and the N-doping (7.1 at%) was confirmed by X-ray photoelectron spectroscopy (XPS). The oxygen reduction/evolution reaction (ORR/OER) performance of N-doped HMC was evaluated using rotating disk electrode (RDE) voltammetry in an alkaline electrolyte. N-doped HMC demonstrated a high ORR onset potential of -0.055 V (vs. Hg/HgO) and excellent stability. The outstanding bifunctional activity was implemented in a practical Zn-air battery (ZAB), which exhibited a small charge-discharge voltage polarization of 0.89 V and high stability over repeated cycling.

Metal free nitrogen doped hollow mesoporous graphene-analogous spheres as effective electrocatalyst for oxygen reduction reaction

Nitrogen-doped hollow mesoporous carbon spheres has been synthesized from mesoporous silica spheres using glycine as carbon and nitrogen precursor. The wall of the spheres is composed by broken graphene. The metal free nitrogen-doped hollow mesoporous carbon spheres are proven to be active electrocatalyst for the oxygen reduction reaction in alkaline solution. A unique advantage of the nitrogen-doped hollow mesoporous carbon sphere is its methanol-tolerant property because of the absence of active metal. The catalytic activity is ascribed to the pyridinic-nitrogen formed during pyrolysis and the graphene-like structure. To the best of our knowledge this is the first report on the nitrogen-doped hollow mesoporous carbon sphere as a metal-free electrocatalyst for the oxygen reduction reaction which is an important reaction in fuel cell. The prepared mesoporous carbon material can also be used as catalyst support and find application both in the anode and cathode of fuel cell.