Multi-heteroatom doped porous carbon derived from insect feces for capacitance-enhanced sodium-ion storage

The large-scale application of sodium ion batteries(SIBs)is limited by economic and environmental factors.Here,we prepare multi-heteroatom self-doped hierarchical porous carbon(HHPC)with a honeycomb-like structure by one-step carbonization method using high-yield and low-cost biomass silkworm excrement as a precursor.As an anode for SIB,HHPC-1100 exhibits a capacity of 331.7 mA h g^(-1) at 20 mA g^(-1),while it also reveals remarkable rate performance and stable long cycle capability due to its abundant pore structure and proper amount of hetero atom doping.Moreover,the synergistic effect of O,N,S,P co-doping in carbon materials on sodium ion adsorption is verified by the first-principles study,which provide a theoretical basis for the prominent electrochemical performance of the material.

Heteroatom Doped Multi-Layered Graphene Material for Hydrogen Storage Application

A variety of distinctive techniques have been developed to produce graphene sheets and their functionalized subsidiaries or composites. The production of graphene sheets by oxidative exfoliation of graphite can be a suitable route for the preparation of high volumes of graphene derivatives. P-substituted graphene material is developed for its application in hydrogen sorption in room temperature. Phosphorous doped graphene material with multi-layers of graphene shows a nearly ~2.2 wt% hydrogen sorption capacity at 298 K and 100 bar. This value is higher than that for reduced graphene oxide (RGO without phosphorous).

Small but mighty:Empowering sodium/potassium-ion battery performance with S-doped SnO_(2) quantum dots embedded in N,S codoped carbon fiber network

SnO_(2) has been extensively investigated as an anode material for sodium-ion batteries(SIBs)and potassium-ion batteries(PIBs)due to its high Na/K storage capacity,high abundance,and low toxicity.However,the sluggish reaction kinetics,low electronic conductivity,and large volume changes during charge and discharge hinder the practical applications of SnO_(2)-based electrodes for SIBs and PIBs.Engineering rational structures with fast charge/ion transfer and robust stability is important to overcoming these challenges.Herein,S-doped SnO_(2)(S-SnO_(2))quantum dots(QDs)(≈3 nm)encapsulated in an N,S codoped carbon fiber networks(S-SnO_(2)-CFN)are rationally fabricated using a sequential freeze-drying,calcination,and S-doping strategy.Experimental analysis and density functional theory calculations reveal that the integration of S-SnO_(2) QDs with N,S codoped carbon fiber network remarkably decreases the adsorption energies of Na/K atoms in the interlayer of SnO_(2)-CFN,and the S doping can increase the conductivity of SnO_(2),thereby enhancing the ion transfer kinetics.The synergistic interaction between S-SnO_(2) QDs and N,S codoped carbon fiber network results in a composite with fast Na+/K+storage and extraordinary long-term cyclability.Specifically,the S-SnO_(2)-CFN delivers high rate capacities of 141.0 mAh g^(−1) at 20 A g^(−1) in SIBs and 102.8 mAh g^(−1) at 10 A g^(−1) in PIBs.Impressively,it delivers ultra-stable sodium storage up to 10,000 cycles at 5 A g^(−1) and potassium storage up to 5000 cycles at 2 A g^(−1).This study provides insights into constructing metal oxide-based carbon fiber network structures for high-performance electrochemical energy storage and conversion devices.

Heteroatom-doped porous carbon from methyl orange dye wastewater for oxygen reduction

Banana peel-derived porous carbon(BPPC) was prepared from banana peel and used as an adsorbent for methyl orange(MO) wastewater removal. BPPC-MO50 is a N,S-doped BPPC obtained via secondary carbonization. The BPPC-MO50 exhibited a high specific surface area of1774.3 m^2/g. Heteroatom-doped porous carbon(PC) was successfully synthesized from the BPPC absorbed MO at high temperature and used for oxygen reduction. The BPPC-MO50 displayed the highest ORR onset potential among all carbon-based electrocatalysts, i.e., 0.93 V vs.reversible hydrogen electrode(RHE). This is the first report to describe porous carbon-activated materials from agriculture and forestry waste that is used for adsorption of dyes from wastewater via an enhanced heteroatom(N,S) content. These results may contribute to the sustainable development of dye wastewater treatment by transforming saturated PC into an effective material and has potential applications in fuel cells or as energy sources.

Heteroatom-doped porous carbon-supported single-atom catalysts for electrocatalytic energy conversion

Electrocatalysts play a crucial role in the development of renewable energy conversion and storage nanotechnologies.The unique advantages of heteroatom-doped porous carbon-supported single-atom electrocatalysts(SAC-HDPCs)are clear.These SAC-HDPCs exhibit outstanding activity,selectivity and stability due to their distinct electronic structure,satisfactory conductivity,controllable porosity and heteroatomdoping effect.Rapid and significant developments involving the synthesis,characterization,and structure-property-function relationship of SAC-HDPCs have been made in recent years.In this review,we describe recent research efforts involving advanced(in situ)characterization techniques,innovative synthetic strategies,and electrochemical energy conversion examples of SAC-HDPCs.The electrocatalytic performance of SAC-HDPCs is further considered at an atomic level,and the mechanisms underlying this performance are also discussed in detail.We expect that these analyses and deductions will be useful for the design of new materials and may help to establish a foundation for the design of future SAC-HDPCs.

Constrained-volume assembly of organometal confined in polymer to fabricate multi-heteroatom doped carbon for oxygen reduction reaction

The design and preparation of non-precious metal and carbon-based nanocomposites are critical to the development of efficient catalysts for technologies ranging from water splitting to fuel cell. Here, we present a constrained-volume self-assembly process for the one-step continuous precipitation-induced formation of soft colloidal particles, in which hydrophobic organoferrous compound,（Ph3P）2Fe（CO）3, is encapsulated within poly（styrene-co-acrylonitrile） nanoparticles（NPs）. The protective and confining polymer matrix ensures uniform carbonization and dispersion of（Ph3P）2Fe（CO）3 within a carbon matrix after a pyrolysis process. The obtained carbon NPs are successfully co-doped with Fe, P and N with a relatively high surface area of-380 m^2 g^（-1）. The Fe-P-N-doped carbon catalyst exhibits high catalytic performance and stability toward oxygen reduction reaction in both alkaline and acidic electrolytes via a favorable four-electron pathway. Meanwhile, the catalytic capability of Fe-P-N-doped carbon can be tailored by the tunable nanostructures.

Heteroatom-Induced Accelerated Kinetics on Nickel Selenide for Highly Efficient Hydrazine-Assisted Water Splitting and Zn-Hydrazine Battery

Hydrazine-assisted water electrolysis is a promising energy conversion technology for highly efficient hydrogen production.Rational design of bifunctional electrocatalysts,which can simultaneously accelerate hydrogen evolution reaction(HER)/hydrazine oxidation reaction(HzOR)kinetics,is the key step.Herein,we demonstrate the development of ultrathin P/Fe co-doped NiSe_(2) nanosheets supported on modified Ni foam(P/Fe-NiSe_(2)) synthesized through a facile electrodeposition process and subsequent heat treatment.Based on electrochemical measurements,characterizations,and density functional theory calculations,a favorable“2+2”reaction mechanism with a two-step HER process and a two-step HzOR step was fully proved and the specific effect of P doping on HzOR kinetics was investigated.P/Fe-NiSe_(2) thus yields an impressive electrocatalytic performance,delivering a high current density of 100 mA cm^(−2) with potentials of−168 and 200 mV for HER and HzOR,respectively.Additionally,P/Fe-NiSe_(2) can work efficiently for hydrazine-assisted water electrolysis and Zn-Hydrazine(Zn-Hz)battery,making it promising for practical application.

A study of highly activated hydrogen evolution reaction performance in acidic media by 2D heterostructure of N and S doped graphene on MoO_(x)

Herein,a layer of molybdenum oxide(MoO_(x)),a transition metal oxide(TMO),which has outstanding catalytic properties in combination with a carbonbased thin film,is modified to improve the hydrogen production performance and protect the MoO_(x)in acidic media.A thin film of graphene is transferred onto the MoO_(x)layer,after which the graphene structure is doped with N and S atoms at room temperature using a plasma doping method to modify the electronic structure and intrinsic properties of the material.The oxygen functional groups in graphene increase the interfacial interactions and electrical contacts between graphene and MoO_(x).The appearance of surface defects such as oxygen vacancies can result in vacancies in MoO_(x).This improves the electrical conductivity and electrochemically accessible surface area.Increasing the number of defects in graphene by adding dopants can significantly affect the chemical reaction at the interfaces and improve the electrochemical performance.These defects in graphene play a crucial role in the adsorption of H^(+)ions on the graphene surface and their transport to the MoO_(x)layer underneath.This enables MoO_(x)to participate in the reaction with the doped graphene.N^(‐)and S^(‐)doped graphene(NSGr)on MoO_(x)is active in acidic media and performs well in terms of hydrogen production.The initial overpotential value of 359 mV for the current density of−10 mA/cm^(2)is lowered to 228 mV after activation.

The effect of the carbon components on the performance of carbonbased transition metal electrocatalysts for the hydrogen evolution reaction

The hydrogen evolution reaction(HER)is a promising way to produce hydrogen,and the use of non-precious metals with an excellent electrochemical performance is vital for this.Carbon-based transition metal catalysts have high activity and stability,which are important in reducing the cost of hydrogen production and promoting the development of the hydrogen production industry.However,there is a lack of discussion regarding the effect of carbon components on the performance of these electrocatalysts.This review of the literature discusses the choice of the carbon components in these catalysts and their impact on catalytic performance,including electronic structure control by heteroatom doping,morphology adjustment,and the influence of self-supporting materials.It not only analyzes the progress in HER,but also provides guidance for synthesizing high-performance carbon-based transition metal catalysts.

Electron-transporting boron-doped polycyclic aromatic hydrocarbons:Facile synthesis and heteroatom doping positions-modulated optoelectronic properties

While heteroatom doping serves as a powerful strategy for devising novel polycyclic aromatic hydrocarbons(PAHs), the further fine-tuning of optoelectronic properties via the precisely altering of doping patterns remains a challenge. Herein, by changing the doping positions of heteroatoms in a diindenopyrene skeleton, we report two isomeric boron, sulfur-embedded PAHs, named Anti-B_(2)S_(2) and Syn-B_(2)S_(2), as electron transporting semiconductors. Detailed structure-property relationship studies revealed that the varied heteroatom positions not only change their physicochemical properties, but also largely affect their solid-state packing modes and Lewis base-triggered photophysical responses. With their low-lying frontier molecular orbital levels, n-type characteristics with electron mobilities up to 1.5 × 10^(-3)cm^(2)V^(-1)s^(-1)were achieved in solution-processed organic field-effect transistors. Our work revealed the critical role of controlling heteroatom doping patterns for designing advanced PAHs.

Flame-assisted ultrafast synthesis of functionalized carbon nanosheets for high-performance sodium storage

The unique structural features of hard carbon(HC)make it a promising anode candidate for sodium-ion batteries(SIB).However,traditional methods of preparing HC require special equipment,long reaction times,and large energy consumption,resulting in low throughputs and efficiency.In our contribution,a novel synthesis method is proposed,involving the formation of HC nanosheets(NS-CNs)within minutes by creating an anoxic environment through flame combustion and further introducing sulfur and nitrogen sources to achieve heteroatom doping.The effect of heterogeneous element doping on the microstructure of HC is quantitatively analyzed by high-resolution transmission electron microscopy and image processing technology.Combined with density functional theory calculation,it is verified that the functionalized HC exhibits stronger Na^(+)adsorption ability,electron gain ability,and Na^(+) migration ability.As a result,NS-CNs as SIB anodes provide an ultrahigh reversible capacity of 542.7mAh g^(-1) at 0.1Ag^(-1),and excellent rate performance with a reversible capacity of 236.4mAh g^(-1) at 2Ag^(-1) after 1200 cycles.Furthermore,full cell assembled with NS-CNs as the can present 230mAh g^(-1) at 0.5Ag^(-1) after 150 cycles.Finally,in/ex situ techniques confirm that the excellent sodium storage properties of NS-CNs are due to the construction of abundant active sites based on the novel synthesis method for realizing the reversible adsorption of Na^(+).This work provides a novel strategy to develop novel carbons and gives deep insights for the further investigation of facile preparation methods to develop high-performance carbon anodes for alkali-ion batteries.

Hydrogen evolution reaction activity enhancement from active site turnover mechanism

Although heteroatom doping is an effective way to improve the catalytic activity of transition metal phosphides(TMPs),the mechanism of activity enhancement needs to be further refined.To this end,we synthesized a Co-doped Ni_(2)P catalyst as a research model and found that the introduction of heterogeneous Co reconstructed the charge distribution around the P site,which effectively enhanced the hydrogen evolution reaction(HER)activity of the pure Ni_(2)P.Based on in-situ Raman real-time monitoring technology,we monitored for the first time that Co doping triggered a switch of the active site(from the original Co-active site to the P-active site),which promoted the adsorption of H_(2)O to enhance the HER activity.The density functional theory(DFT)calculations indicated that the P site of Co-Ni_(2)P expressed the highest activity and the Ni site of pure Ni_(2)P expressed the highest activity,which further confirms the in-situ Raman monitoring results.The active site turnover mechanism discovered in this study will undoubtedly provide more rational and targeted ideas for future catalyst design.

Sulphur-doped ordered mesoporous carbon with enhanced electrocatalytic activity for the oxygen reduction reaction

Metal-free, heteroatom functionalized carbon-based catalysts have made remarkable progress in recent years in a wide range of applications related to energy storage and energy generation. In this study, high surface area mesoporous ordered sulphur doped carbon materials are obtained via one-pot hydrothermal synthesis of carbon/SBA-15 composite after removal of in-situ synthesized hard template SiO2. 2-thiophenecarboxy acid as sulphur source gives rise to sulphur doping level of 5.5 wt%. Comparing with pristine carbon, the sulphur doped mesoporous ordered carbon demonstrates improved electro-catalytic activity in the oxygen reduction reaction in alkaline solution. (C) 2016 Science Press and Dalian Institute of Chemical Physics, Chinese Academy of Sciences. Published by Elsevier B.V. and Science Press. All rights reserved.

Review on Heteroatom Doping Carbonaceous Materials Toward Electrocatalytic Carbon Dioxide Reduction

Carbon dioxide(CO_(2))reduction into chemicals or fuels by electrocatalysis can eff ectively reduce greenhouse gas emissions and alleviate the energy crisis.Currently,CO_(2)electrocatalytic reduction(CO_(2)RR)has been considered as an ideal way to achieve“carbon neutrality.”In CO_(2)RR,the characteristics and properties of catalysts directly determine the reaction activity and selectivity of the catalytic process.Much attention has been paid to carbon-based catalysts because of their diversity,low cost,high availability,and high throughput.However,electrically neutral carbon atoms have no catalytic activity.Incorpo-rating heteroatoms has become an eff ective strategy to control the catalytic activity of carbon-based materials.The doped carbon-based catalysts reported at present show excellent catalytic performance and application potential in CO_(2)RR.Based on the type and quantity of heteroatoms doped into carbon-based catalysts,this review summarizes the performances and catalytic mechanisms of carbon-based materials doped with a single atom(including metal and without metal)and multi atoms(including metal and without metal)in CO_(2)RR and reveals prospects for developing CO_(2)electroreduction in the future.

Nitrogen and fluorine co-doped TiO_(2)/carbon microspheres for advanced anodes in sodium-ion batteries: High volumetric capacity, superior power density and large areal capacity

Fast charging and high volumetric capacity are two of the critical demands for sodium-ion batteries(SIBs).Although nanostructured materials achieve outstanding rate performance,they suffer from low tap density and small volumetric capacity.Therefore,how to realize large volumetric capacity and high tap density simultaneously is very challenging.Here,N/F co-doped TiO_(2)/carbon microspheres(NF- TiO_(2)/C)are synthesized to achieve both of them.Theoretical calculations reveal that N and F co-doping increases the contents of oxygen vacancies and narrows the bandgaps of TiO_(2) and C,improving the electronic conductivity of NF- TiO_(2)/C.Furthermore,NF- TiO_(2)/C exhibits the high binding energy and low diffusion energy barrier of Na+,significantly facilitating Na+storage and Na+diffusion.Therefore,NF- TiO_(2)/C offers a high tap density(1.51 g cm^(-3)),an outstanding rate performance(125.9 mAh g^(-1) at 100 C),a large volumetric capacity(190 mAh cm^(-3) at 100 C),a high areal capacity(4.8 mAh cm^(-2))and an ultra-long cycling performance(80.2%after 10,000 cycles at 10 C)simultaneously.In addition,NF- TiO_(2)/C||Na_(3)V_(2)(PO_(4))_(3) full cells achieve an ultrahigh power density of 25.2 kW kg^(-1).These results indicate the great promise of NF- TiO_(2)/C as a high-volumetric-capacity and high-power-density anode material of SIBs.

Free-standing phosphorous-doped molybdenum nitride in 3D carbon nanosheet towards hydrogen evolution at all pH values

Highly efficient electrocatalysts towards hydrogen evolution reaction(HER) with large current density at all-pH values are critical for the sustainable hydrogen production. Herein, we report a free-standing HER electrode, phosphorous-doped molybdenum nitride nanoparticles embedded in 3-dimentional carbon nanosheet matrix(P-Mo2N-CNS) fabricated via one-step carbonization and in-situ formation. The asprepared catalyst shows free-standing architecture with interconnected porous microstructure. P-doped Mo2N nanoparticles with an average diameter of 4.4 nm are well embedded in the 3-dimentional vertical carbon nanosheets matrix. Remarkable electrocatalytic HER performance is observed in alkaline, neutral and acidic media at large current densities. The overpotential of P-Mo2N-CNS to drive a current density of 100 mA cm-2 in 0.5 M H2SO4 and 1.0 M PBS is only 181 and 221 mV, respectively. In particular, the current density reaches up to 1000 mA cm-2 at a low overpotential of 256 mV in 1.0 M KOH, much better than that of the commercial Pt/C catalyst. Density functional theory calculations suggest the optimized H sorption kinetics on Mo2N after P doping, elucidating the superior activity.

Confinement of sulfur-doped NiO nanoparticles into N-doped carbon nanotube/nanofiber-coupled hierarchical branched superstructures:Electronic modulation by anion doping boosts oxygen evolution electrocatalysis

The search for non-precious and efficient electrocatalysts towards the oxygen evolution reaction(OER)is of vital importance for the future advancement of multifarious renewable energy conversion/storage technologies.Electronic modulation via heteroatom doping is recognized as one of the most forceful leverages to enhance the electrocatalytic activity.Herein,we demonstrate a delicate strategy for the in-situ confinement of S-doped Ni O nanoparticles into N-doped carbon nanotube/nanofiber-coupled hierarchical branched superstructures(labeled as S-Ni O@N-C NT/NFs).The developed strategy simultaneously combines enhanced thermodynamics via electronic regulation with accelerated kinetics via nanoarchitectonics.The S-doping into Ni O lattice and the 1 D/1 D-integrated hierarchical branched carbon substrate confer the resultant S-Ni O@N-C NT/NFs with regulated electronic configuration,enriched oxygen vacancies,convenient mass diffusion pathways and superior architectural robustness.Thereby,the SNi O@N-C NT/NFs display outstanding OER properties with an overpotential of 277 m V at 10 m A cm^(-2)and impressive long-term durability in KOH medium.Density functional theory(DFT)calculations further corroborate that introducing S-dopant significantly enhances the interaction with key oxygenate intermediates and narrow the band gap.More encouragingly,a rechargeable Zn-air battery using an air-cathode of Pt/C+S-Ni O@N-C NT/NFs exhibits a lower charge voltage and preferable cycling stability in comparison with the commercial Pt/C+Ru O_(2)counterpart.This study highlighting the concurrent consideration of electronic regulation,architectural design and nanocarbon hybridization may shed light on the future exploration of economical and efficient electrocatalysts.

Oxygen vacancies and V co-doped Co_(3)O_(4) prepared by ion implantation boosts oxygen evolution catalysis

Introducing heteroatoms and defects is a significant strategy to improve oxygen evolution reaction(OER)performance of electrocatalysts.However,the synergistic interaction of the heteroatom and defect still needs further investigations.Herein,we demonstrated an oxygen vacancy-rich vanadium-doped Co_(3)O_(4)(V-Ov-Co_(3)O_(4)),fabricated by V-ion implantation,could be used for high-efficient OER catalysis.X-ray photoelectron spectra(XPS)and density functional theory(DFT)calculations show that the charge density of Co atom increased,and the reaction barrier of reaction pathway from O∗to HOO∗decreased.V-Ov-Co_(3)O_(4) catalyst shows a low overpotential of 329 mV to maintain current density of 10 mA·cm^(−2),and a small Tafel slope of 74.5 mV·dec^(−1).This modification provides us with valuable perception for future design of heteroatom-doped and defect-based electrocatalysts.

Heteroatom doping regulates the catalytic performance of singleatom catalyst supported on graphene for ORR

Replacing fossil fuels with fuel cells is a feasible way to reduce global energy shortages and environmental pollution.However,the oxygen reduction reaction(ORR)at the cathode has sluggish kinetics,which limits the development of fuel cells.It is significant to develop catalysts with high catalytic activity of ORR.The single-atom catalysts(SACs)of Pt supported on heteroatom-doped graphene are potential candidates for ORR.Here we studied the SACs of Pt with different heteroatoms doping and screened out Pt-C_(4) and Pt-C_(3)O_(1) structures with only 0.13 V overpotential for ORR.Meanwhile,it is found that B atoms doping could weaken the adsorption capacity of Pt,while N or O atoms doping could enhance it.This regularity was verified on Fe SACs.Through the electronic interaction analysis between Pt and adsorbate,we explained the mechanism of this regularity and further proposed a new descriptor named corrected d-band center(ε_(d-corr))to describe it.This descriptor is an appropriate reflection of the number of free electrons of the SACs,which could evaluate its adsorption capacity.Our work provides a purposeful regulatory strategy for the design of ORR catalysts.

Micropore engineering on hollow nanospheres for ultra-stable sodium-selenium batteries

Attracted by high energy density and considerable conductivity of selenium(Se),Na-Se batteries have been deemed promising energy-storage systems.But,it still suffers from sluggish kinetic behaviors and similar“shuttling effect”to S-electrodes.Herein,utilizing uniform hollow carbon spheres as precursors,Se-material is effectively loaded through vapor-infiltration method.Owing to the distribution of optimized pores,the content of microspores could be up to~60%(<2 nm),serving important roles for the physical confinement effect.Meanwhile,the rich oxygen-containing groups and N-elements could be noted,inducing the evolution of electron-moving behaviors.More significantly,assisted by the interfacial C-Se bonds and tiny Se distributions,Se electrodes are activated during cycling.Used as cathodes for Na-Se systems,the as-resulted samples display a capacity of 593.9 mA h g^(-1)after 100 cycles at the current density of 0.1 C.Even after 6000 cycles,the capacity could be still kept at about 225 mA h g^(-1)at 5.0 C.Supported by the detailed kinetic analysis,the designed microspores size induces the increasing redox reaction of nano Se,whilst the surface traits further render the enhancement of pseudo-capacitive contributions.Moreover,after cycling,the product Sex(x<4)in pores serves as the primary active material.Given this,the work is anticipated to provide an effective strategy for advanced electrodes for Na-Se systems.