Synthesis of boron, nitrogen co-doped porous carbon from asphaltene for high-performance supercapacitors

Oxidized asphaltene （OA）, a thermosetting material with plenty of functional groups, is synthesized from asphaltene （A） using HNO3]HzSO4 as the oxidizing agent. Boron, nitrogen co-doped porous carbon （BNC-OA） is prepared by carbonization of the mixture of boric acid and OA at 1173 K in an argon atmosphere. X-ray photoelectron spectroscopy （XPS） characterization reveals that the BNC-OA has a nitrogen content of 3.26 at.% and a boron content of 1.31 at.%, while its oxidation-free counterpart （BNC-SA） has a nitrogen content of 1.61 at.% and a boron content of 3.02 at.%. The specific surface area and total pore volume of BNC-OA are 1103 m2·g^-1 and 0.921 cm3·g^-1, respectively. At a current density of 0.1 A·g^-1, the specific capacitance of BNC-OA is 335 F·g^-1 and the capacitance retention can still reach 83% at 1 A·g^-1. The analysis shows that the superior electrochemical performance of the BNC-OA is attributed to the pseudocapacitance behavior of surface heteroatom functional groups and an abundant pore-structure. Boron, nitrogen co-doped porous carbon is a promising electrode material for supercapacitors.

A carbon material doped with both porous FeO_(x) and N as an efficient catalyst for oxygen reduction reactions

To replace precious metal oxygen reduction reaction(ORR)electrocatalysts,many transition metals and N-doped car-bon composites have been proposed in the last decade resulting in their rapid development as promising non-precious metal catalysts.We used Ketjenblack carbon as the precursor and mixed it with a polymeric ionic liquid(PIL)of[Hvim]NO_(3) and Fe(NO_(3))_(3),which was thermally calcined at 900℃ to produce a porous FeO_(x),N co-doped carbon material denoted FeO_(x)-N/C.Because the PIL of[Hvim]NO_(3) strongly combines with and disperses Fe^(3+)ions,and NO_(3)−is thermally pyrolyzed to form the porous structure,the FeO_(x)-N/C catalyst has a high electrocatalytic activity for the ORR in both 0.1 mol L^(−1) KOH and 0.5 mol L^(−1) H_(2)SO_(4) electrolytes.It was used as the catalyst to assemble a zinc-air battery,which had a peak power density of 185 mW·cm^(−2).Its superior electrocatalytic activity,wide pH range,and easy preparation make FeO_(x)-N/C a promising electrocatalyst for fuel cells and metal-air batteries.

Inherent mass transfer engineering of a Co,N co-doped carbon material towards oxygen reduction reaction

Oxygen reduction reaction (ORR) is an important process for the conversion and utilization of a wide range of renewable energy sources, and is critical for the shape of future energy scenario [1–10]. However, ORR is a complex four-electron transfer process and is kinetically sluggish. It is urgent to develop high-efficient electrocatalysts to solve this problem [11–15]. Up to now, precious metal-based catalysts such as Pt-based electrocatalysts have been widely studied and found to be one of the most efficient electrocatalysts for ORR. However, the high price and the small reserves limit their large-scale commercialization [10,16–23]. Therefore, in order to fulfill needs for the practical applications, it is necessary to develop low-cost electrocatalysts, also with high activity and great stability [19,24–28].

Hierarchical porous nitrogen,oxygen,and phosphorus ternary doped hollow biomass carbon spheres for high-speed and long-life potassium storage

Limited lithium resources have promoted the exploration of new battery technologies.Among them,potassium-ion batteries are considered as promising alternatives.At present,commercial graphite and other carbon-based materials have shown good prospects as anodes for potassium-ion batteries.However,the volume expansion and structural collapse caused by periodic K+insertion/extraction have severely restricted further development and application of potassium-ion batteries.A hollow biomass carbon ball(NOP-PB)ternarily doped with N,O,and P was synthesized and used as the negative electrode of a potassium-ion battery.X-ray photoelectron spectroscopy,Fourier‐transform infrared spectroscopy,and transmission electron microscopy confirmed that the hollow biomass carbon spheres were successfully doped with N,O,and P.Further analysis proved that N,O,and P ternary doping expands the interlayer distance of the graphite surface and introduces more defect sites.DFT calculations simultaneously proved that the K adsorption energy of the doped structure is greatly improved.The solid hollow hierarchical porous structure buffers the volume expansion of the potassium insertion process,maintains the original structure after a long cycle and promotes the transfer of potassium ions and electrons.Therefore,the NOP‐PB negative electrode shows extremely enhanced electrochemical performance,including high specific capacity,excellent long‐term stability,and good rate stability.

Cobalt-nitrogen co-doped porous carbon sphere as highly efficient catalyst for liquid-phase cyclohexane oxidation with molecular oxygen and the active sites investigation

The selective oxidation of cyclohexane to cyclohexanone and cyclohexanol(KA oil)is a challenging issue in the chemical industry.At present the industrial conversion of cyclohexane to cyclohexanone and cyclohexanol is normally controlled at less than 5%selectivity.Thus,the development of highly active and stable catalysts for the aerobic oxidation of cyclohexane is necessary to overcome this low-efficiency process.Therefore,we have developed a cobalt-nitrogen co-doped porous sphere catalyst,Co-NC-x(x is the Zn/Co molar ratio,where x=0,0.5,1,2,and 4)by pyrolyzing resorcinol-formaldehyde resin microspheres.It achieved 88.28%cyclohexanone and cyclohexanol selectivity and a cyclohexane conversion of 8.88%under Co-NC-2.The results showed that the introduction of zinc effectively alleviated the aggregation of Co nanoparticles and optimized the structural properties of the material.In addition,Co0 and pyridinic-N are proposed to be the possible active species,and their proportion efficiently increased in the presence of Zn^(2+)species.In this study,we developed a novel strategy to design highly active catalysts for cyclohexane oxidation.

N,P co-doped 3D porous carbon with self-assembled morphological control via template-free method for potassiumion battery anodes

The larger ionic radius of potassium ions than that of lithium ions significantly limits the accomplishment of rapid diffusion kinetics in graphite electrodes for potassium-ion batteries(PIBs),resulting in comparatively poor rate performance and cycle stability.Herein,we report a high-rate performance and cycling stability amorphous carbon electrode achieved through nitrogen and phosphorous co-doping.The as-prepared N,P co-doped carbon electrodes have distinct 3D structures with large surface areas,hierarchical pore architectures,and increased interlayer spaces resulting from the direct pyrolysis of supramolecular self-assembled aggregates without templates.The obtained electrode N3P1 exhibits a reversible specific capacity of 258 m Ah·g^(-1)at a current density of 0.1A·g^(-1)and a good long-term cycle performance(96.1%capacity retention after 800 cycles at 0.5 A·g^(-1)).Kinetic investigations show that the N3P1 electrode with the welldeveloped porous structure and large number of surface defects exhibits capacitive-driven behavior at all scan rates,which may be attributed by N and P co-doping.Ex-situ transmission electron microscopy analyses in the fully discharged and charged states demonstrate structural stability and reversibility owing to the expanded interlayer space.The suggested synthesis approach is simple and effective for producing heteroatom-doped carbon materials for PIBs and other advanced electrochemical energy storage materials.

Fabrication of N,S co-doped porous carbon nanofibers as anode material for sodium-ion batteries with high performance

The N,S co-doped porous carbon nanofibers were fabricated by the carbonization of[Zn_(2)(tdc)_(2)(MA)]n MOFs/polyacrylonitrile nanofibers composite,which was produced by the electrospinning technology.The electrochemical results show that the N,S co-doped porous carbon nanofibers can achieve capacity of 201.2 mAh·g^(-1)at the current density of 0.05 A·g^(-1).Furthermore,the reversible capacity still has 161.3 mAh·g^(-1)even at a high current density of 1 A·g^(-1)after 600 cycles.The superior electrochemical performance shows that the N,S co-doped porous carbon nanofibers electrode material can be used as an ideal anode material for sodium-ion batteries.

Fe/N co-doped nano-TiO_(2)wrapped mesoporous carbon spheres for synergetically enhanced adsorption and photocatalysis

Carbon-based adsorption and TiO_(2)-based photocatalysis are both safe and low-cost ways of pollutant pu-rification.Constructing C-TiO_(2)architectures can effectively improve removal efficiency.However,most of those carbon frames only acted as supporting substrates,exhibiting rather limited synergistic action from TiO_(2)and carbon.Herein,Fe/N co-doped nano-TiO_(2)wrapped on mesoporous carbon spheres with a core-shell structure was designed.The Fe,N co-doped carbon sphere with a hierarchical structure im-proved the synergy of adsorption and transfer during the photocatalytic process.Without extra dopant,the Fe and N partly exposed on the surface realized the in-situ migrating into the TiO_(2)shell to en-hance the interface effect,which significantly promoted the photocatalytic efficiency of the composite.Furthermore,the photocatalytic efficiency of the composite was investigated through two typical pollu-tants under visible-light irradiation.The degradation efficiencies for rhodamine B and paraxylene were 96.2%in 60 min and 94.1%in 20 min,respectively,with the apparent rate constant of 0.045 min^(-1)and 0.049 min^(-1),8.3 and 11.4 times of that for bare TiO_(2).The composite is likely advantageous for treating diverse environmental pollutants.

Highly N/O co-doped ultramicroporous carbons derived from nonporous metal-organic framework for high performance supercapacitors

A new nonporous Zn-based metal-organic framework(NPMOF) synthesized from a high nitrogencontaining rigid ligand was converted into porous carbon materials by direct carbonization without adding additional carbon sources.A series of NPMOF-derived porous carbons with very high N/O contents(24.1% for NPMOF-700,20.2% for NPMOF-800,15.1% for NPMOF-900) were prepared by adjusting the pyrolysis temperatures.The NPMOF-800 fabrica ted electrode exhibits a high capacitance of220 F/g and extremely large surface area normalized capacitance of 57.7 μF/cm~2 compared to other reported MOF-derived porous carbon electrodes,which could be attributed to the abundant ultramicroporosity and high N/O co-doping.More importantly,symmetric supercapacitor assembled with the MOF-derived carbon manifests prominent stability,i.e.,99.1 % capacitance retention after 10,000 cycles at 1.0 A/g.This simple preparation of MOF-derived porous carbon materials not only finds an application direction for a variety of porous or even nonporous MOFs,but also opens a way for the production of porous carbon materials for superior energy storage.

Nitrogen-oxygen co-doped corrugation-like porous carbon for high performance supercapacitor

Nitrogen-oxygen co-doped corrugation-like porous carbon （NO-PC） has been developed by direct pyrolysis of formaldehyde-melamine polymer containing manganese nitrate. The melamine, formaldehyde and manganese nitrate act as nitrogen, oxygen source and pore-foaming agent, respectively. NO-PC exhibits favorable porous architecture for efficient ion transfer and moderate heteroatom doping for additional pseudocapacitance, which synergistically enhances the electrochemical performance of the NO-PC-based supercapacitor. The electrode delivers specific capacitance of 240 Fig at 0.3 A/g when tested in 6 mol/L KOH electrolyte, good rate capability （capacitance retention of 83.3% at 5 A/g） as well as stable cycling performance （capacitance remains -96% after 10000 cycles at 3 A/g）. The facile synthesis with unique architecture and chemistry modification offers a promising candidate for electrode material of energy storage devices.

Self-sacrificial template synthesis of Fe, N co-doped porous carbon as efficient oxygen reduction electrocatalysts towards Zn-air battery application

Designing highly efficient non-precious based electrocatalysts for oxygen reduction reaction(ORR) is of significance for the rapid development of metal-air batteries.Herein,a hydrothermal-pyrolysis method is employed to fabricate Fe,N co-doped porous carbon materials as effective ORR electrocatalyst through adopting graphitic carbon nitride(g-C_(3)N_(4)) as both the self-sacrificial templates and N sources.The gC_(3)N_(4)provides a high concentration of unsaturated pyridine-type N to coordinate with iron to form Fe-N active sites.Through adjusting the Fe doping amounts,it is proved that appropriate Fe doping content is conducive to the construction of abundant defects and active sites of Fe-N.The as-prepared catalyst exhibits superior electrocatalytic ORR performance in alkaline media with half-wave potential(E_(1/2)=0.82 V) and onset potential(E_(onset)=0.95 V),equivalent to the commercial Pt/C catalyst.Moreover,there is almost no activity loss after 10 k continuous cyclic voltammetry cycles and methanol tolerance,indicating the excellent durability and superior methanol tolerance.Remarkably,when assembled as the cathode in a Zn-air battery,the device displays a power density of 99 mW/cm^(2),an open-circuit potential of 1.48 V and long-term discharge-charge cycling stability,indicating the promising potential to substitute the Pt catalyst for practical application.

Edge-enriched N, S co-doped hierarchical porous carbon for oxygen reduction reaction

The development of carbon materials with high electrochemical performance for next-generation energy device is emerging, especially N, S co-doped carbon materials have sparked intensive attention. However,the exploration of N, S co-doped carbon with well-defined active sites and hierarchical porous structures are still limited. In this study, we prepared a series of edge-enriched N, S co-doped carbon materials through pyrolysis of thiourea(TU) encapsulated in zeolitic imidazolate frameworks(TU@ZIF) composites,which delivered very good oxygen reduction reaction(ORR) performance in alkaline medium with onset potential of 0.94 V vs. reversible hydrogen electrode(RHE), good stability and methanol tolerance. Density functional theory(DFT) calculations suggested that carbon atoms adjacent to N and S are probable active sites for ORR intermediates in edge-enriched N, S co-doped carbon materials because higher electron density can enhance O_(2)adsorption, lower formation barriers of intermediates, improving the ORR performance comparing to intact N, S co-doped carbon materials. This study might provide a new pathway for improving ORR activity by the integration engineering of edge sites, and electronic structure of heteroatom doped carbon electrocatalysts.

Boron and nitrogen co-doped porous carbon derived from sodium alginate enhanced capacitive deionization for water purification

Capacitive deionization can alleviate water shortage and water environmental pollution, but performances are greatly determined by the electrochemical and desalination properties of its electrode materials. In this work, B and N co-doped porous carbon with micro-mesoporous structures is derived from sodium alginate by a carbonization, activation, and hydrothermal doping process, which exhibits large specific surface area (2587 m^(2)·g^(‒1)) and high specific capacitance (190.7 F·g^(‒1)) for adsorption of salt ions and heavy metal ions. Furthermore, the materials provide a desalination capacity of 26.9 mg·g−1 at 1.2 V in 500 mg·L^(‒1) NaCl solution as well as a high removal capacity (239.6 mg·g^(‒1)) and adsorption rate (7.99 mg·g^(‒1)·min^(‒1)) for Pb2+ with an excellent cycle stability. This work can pave the way to design low-cost porous carbon with high-performances for removal of salt ions and heavy metal ions.

N,O co-doped porous carbon with rich pseudocapacitive groups exhibiting superior energy density in an acidic 2.4 V Li_(2)SO_(4)electrolyte

Designing a carbon material with a unique composition and surface functional groups for offering high specific capacity in a wide voltage window is of great significance to improve the energy density for the supercapacitor in a cheap and eco-friendly aqueous electrolyte.Herein,we develop an efficient strategy to synthesize a N,O co-doped hierarchically porous carbon(NODPC-1.0)with moderate specific surface area and pore volume as well as rich heteroatoms using a deep eutectic solvent(DES)as an activator.It is found that NODPC-1.0 with a large proportion of pseudocapacitive functional groups(pyrrole-N,pyridineN and carbonyl-quinone)can work stable in an acidic 2 mol/L Li_(2)SO_(4)(pH 2.5)electrolyte,exhibiting specific capacities of 375 and 186 F/g at the current densities of 1.0 and 100 A/g,respectively.Also,the assembled symmetric capacitor using the NODPC-1.0 as the active material and 2 mol/L acidic Li_(2)SO_(4)(pH 2.5)as the electrolyte shows an outstanding energy density of 74.4 Wh/kg at a high power density of 1.44 k W/kg under a broad voltage window(2.4 V).Relevant comparative experiments indicate that H+of the acidic aqueous electrolyte plays a crucial part in enhancement the specific capacity,and the abundant pseudocapacitive functional groups on the surface of the NODPC-1.0 sample play the key role in the improvement of electrochemical cycle stability under a broad voltage window.

A high-performance potassium-ion capacitor based on a porous carbon cathode originated from the Aldol reaction product

Potassium-ion capacitors(KICs) emerge as a promising substitute for the well-developed lithium-ion capacitors(LICs),however,the energy density of KICs is below expectations because of lacking a suitable electrical double-layer positive electrode.Using chemical activation of the Aldol reaction product of acetone with KOH,we synthesized a porous ca rbon with a Brunauer-Emmett-Teller surface area of up to 2947 m2/g and a narrow pore size distribution ranging from 1 nm to 3 nm.Half-cell(versus potassium metal) test demonstrates that this porous carbon has high capacitive performance in K+ based organic electrolytes.Furthermore,a novel KIC fabricated by this porous carbon as the cathode,yields high values of energy density and power density.The processes used to make this porous carbon are readily low-cost to fabricate metal-ion capacitors.

Binary doping of nitrogen and phosphorus into porous carbon: A novel di-functional material for enhancing CO_(2) capture and super-capacitance

Designing of hetero-atomic doped carbon-based systems through pyrolysis of abundant element organic precursors is a novel approach to construct rational porous carbon materials.Herein,a highly-cross-linked triazine polymer is employed to fabricate N,P co-doped porous carbon(A-TDP-12)with tunable active nitrogen in the carbon framework for simultaneous enhancement of CO_(2) capture capability and Supercapacitance(SC).The synthesized A-TDP-12 possesses a typical hierarchically porous framework(micro-pores and meso-pores)with a large surface area(1332 m^(2) g^(-1))and a rich content of N(7.89 at.%)and P(0.74 at.%).It delivers a CO_(2) adsorption capacity of 1.52 and 5.68 mmol g^(-1) at 1 and 5 bar,respectively,with almost no decay after successive 8 recycles.In 6 M KOH aqueous electrolyte,A-TDP-12 exhibits a superior specific capacitance of 172.7 F g^(-1) at a current density of 1 A g^(-1).Even at a high current density of 10 A g^(-1),80%of its initial capacity still remains.This work not only offers a novel strategy for fabricating promising adsorbents and electrodes for CO_(2) uptake and SCs,but also provides new insights into design of porous carbon material for related applications.

Regeneration of photovoltaic industry silicon waste toward high-performance lithium-ion battery anode

The diamond-wire sawing silicon waste(DWSSW)from the photovoltaic industry has been widely considered as a low-cost raw material for lithium-ion battery silicon-based electrode,but the effect mechanism of impurities presents in DWSSW on lithium storage performance is still not well understood;meanwhile,it is urgent to develop a strategy for changing DWSSW particles into high-performance electrode materials.In this work,the occurrence state of impurities presents in DWSSW was carefully analyzed using in situ Ar ion etching technology Then,the novel Si@C@SiO_(x)@PAl-NDC composite was designed through in situ encapsulation strategy.The obtained Si@C@SiO_(x)@PAl-NDC electrode shows a high first capacity of 2343.4 mAh·g^(-1)with an initial Coulombic efficiency(ICE)of 84.4%under current density of 1.0 A·g^(-1),and can deliver an impressive capacity of 984.9 mAh·g^(-1)after 200 cycles.Combined numerical simulation modeling calculations,the increase in proportion of Si^(4+)/Si^(0)and Si^(3+)/Si^(0)valence states in SiO_(x)layer leads to a decrease in von Mises stress,which ultimately improves the cycling structural stability.Meanwhile,the porous 2D-3D aluminum/nitrogen(Al/N)co-doped carbon layer and nanowires on SiO_(x)layer can provide abundant active sites for lithium storage due to its developed hierarchical pores structure,which facilitates ion transport What is more,the performance of Si@C@SiO_(x)@PAl-NDC//LiFePO_(4)full cell shows its great potential in practical application.

The synergistic catalysis on Co nanoparticles and CoNx sites of aniline-modified ZIF derived Co@NCs for oxidative esterification of HMF

An efficient sustainable and scalable strategy for the synthesis of porous cobalt/nitrogen co-doped carbons(Co@NCs) via pyrolysis of aniline-modified ZIFs,has been demonstrated.Aniline can coordinate and absorb on the surface of ZIF(ZIF-CoZn3-PhA),accelerate the precipitation of ZIFs,thus resulting in smaller ZIF particle size.Meanwhile,the aniline on the surface of ZIF-CoZn3-PhA promotes the formation of the protective carbon shell and smaller Co nanoparticles,and increases nitrogen content of the catalyst.Because of these prope rties of Co@NC-PhA-3,the oxidative esterification of 5-hydroxymethylfurfural can be carried out under ambient conditions.According to our experimental and computational results,a synergistic catalytic effect between CoNx sites and Co nanoparticles has been established,in which both Co nanoparticles and CoNx can activate O2 while Co nanoparticles bind and oxidize HMF.Moreover,the formation and release of active oxygen species in CoNx sites are reinfo rced by the electronic interaction between Co nanoparticles and CoNx.