Vacancy defect MoSeTe embedded in N and F co-doped carbon skeleton for high performance sodium ion batteries and hybrid capacitors

Sodium-ion batteries(SIBs) and hybrid capacitors(SIHCs) have garnered significant attention in energy storage due to their inherent advantages,including high energy density,cost-effectiveness,and enhanced safety.However,developing high-performance anode materials to improve sodium storage performa nce still remains a major challenge.Here,a facile one-pot method has been developed to fabricate a hybrid of MoSeTe nanosheets implanted within the N,F co-doped honeycomb carbon skeleton(MoSeTe/N,F@C).Experimental results demonstrate that the incorporation of large-sized Te atoms into MoSeTe nanosheets enlarges the layer spacing and creates abundant anion vacancies,which effectively facilitate the insertion/extraction of Na^(+) and provide numerous ion adsorption sites for rapid surface capacitive behavior.Additionally,the heteroatoms N,F co-doped honeycomb carbon skeleton with a highly conductive network can restrain the volume expansion and boost reaction kinetics within the electrode.As anticipated,the MoSeTe/N,F@C anode exhibits high reversible capacities along with exceptional cycle stability.When coupled with Na_(3)V_(2)(PO_(4))_(3)@C(NVPF@C) to form SIB full cells,the anode delivers a reversible specific capacity of 126 mA h g^(-1) after 100 cycles at 0.1 A g^(-1).Furthermore,when combined with AC to form SIHC full cells,the anode demonstrates excellent cycling stability with a reversible specific capacity of50 mA h g^(-1) keeping over 3700 cycles at 1.0 A g^(-1).In situ XRD,ex situ TEM characterization,and theoretical calculations(DFT) further confirm the reversibility of sodium storage in MoSeTe/N,F@C anode materials during electrochemical reactions,highlighting their potential for widespread practical application.This work provides new insights into the promising utilization of advanced transition metal dichalcogenides as anode materials for Na^(+)-based energy storage devices.

Ultralong nitrogen/sulfur Co-doped carbon nano-hollowsphere chains with encapsulated cobalt nanoparticles for highly efficient oxygen electrocatalysis

The development of simple and effective strategies to prepare electrocatalysts,which possess unique and stable structures comprised of metal/nonmetallic atoms for oxygen reduction reaction(ORR)and oxygen evolution reaction(OER),is currently an urgent issue.Herein,an efficient bifunctional electrocatalyst featured by ultralong N,S-doped carbon nano-hollow-sphere chains about 1300 nm with encapsulated Co nanoparticles(Co-CNHSCs)is developed.The multifunctional catalytic properties of Co together with the heteroatom-induced charge redistribution(i.e.,modulating the electronic structure of the active site)result in superior catalytic activities toward OER and ORR in alkaline media.The optimized catalyst Co-CNHSC-3 displays an outstanding electrocatalytic ability for ORR and OER,a high specific capacity of 1023.6 mAh gZn^(-1),and excellent reversibility after 80 h at 10mA cm^(-2)in a Zn-air battery system.This work presents a new strategy for the design and synthesis of efficient multifunctional carbon-based catalysts for energy storage and conversion devices.

Rationally designed hollow carbon nanospheres decorated with S,P co-doped NiSe_(2) nanoparticles for high-performance potassium-ion and lithium-ion batteries

Hollow nanostructures with external shells and inner voids have been proved to greatly shorten the transport distance of ions/electrons and buffer volume change,especially for the large-sized potassium-ions in secondary batteries.In this work,hollow carbon(HC) nanospheres embedded with S,P co-doped NiSe_(2)nanoparticles are fabricated by "drop and dry" and "dissolving and precipitation" processes to form Ni(OH)2nanocrystals followed by annealing with S and P dopants to form nanoparticles.The resultant S,P-NiSe_(2)/HC composite exhibits excellent cyclic performance with 131.6 mA h g^(-1)at1000 mA g^(-1)after 3000 cycles for K^(+)storage and a capacity of 417.1 mA h g^(-1)at 1000 mA g^(-1)after1000 cycles for Li^(+)storage.K-ion full cells are assembled and deliver superior cycling stability with a ca pacity of 72.5 mA h g^(-1)at 200 mA g^(-1)after 500 cycles.The hollow carbon shell with excellent electrical conductivity effectively promotes the transporta tion and tolerates large volume variation for both K^(+)and Li^(+).Density functional theory calculations confirm that the S and P co-doping NiSe_(2) enables stronger adsorption of K^(+)ions and higher electrical conductivity that contributes to the improved electrochemical performance.

Construction of N,O co-doped carbon anchored with Co nanoparticles as efficient catalyst for furfural hydrodeoxygenation in ethanol

Hydrodeoxygenation of furfural(FF)into 2-methylfuran(MF)is a significant biomass utilization route.However,designing efficient and stable non-noble metal catalyst is still a huge challenge.Herein,we reported the N,O co-doped carbon anchored with Co nanoparticles(Co-SFB)synthesized by employing the organic ligands with the target heteroatoms.Raman,electron paramagnetic resonance(EPR),electrochemical impedance spectroscopy(EIS),and X-ray photoelectron spectroscopy(XPS)characterizations showed that the co-doping of N and O heteroatoms in the carbon support endows Co-SFB with enriched lone pair electrons,fast electron transfer ability,and strong metal-support interaction.These electronic properties resulted in strong FF adsorption as well as lower apparent reaction activation energy.At last,the obtained N,O co-doped Co/C catalyst showed excellent catalytic activity(nearly 100 mol%FF conversion and 94.6 mol%MF yield)and stability for in-situ dehydrogenation of FF into MF.This N,O co-doping strategy for the synthesis of highly efficient catalytic materials with controllable electronic state will provide an excellent opportunity to better understand the structure-function relationship.

Direct observation of the distribution of impurity in phosphorous/boron co-doped Si nanocrystals

Doping in Si nanocrystals is an interesting topic and directly studying the distribution of dopants in phosphorous/boron co-doping is an important issue facing the scientific community.In this study,atom probe tomography is performed to study the structures and distribution of impurity in phosphorous/boron co-doped Si nanocrystals/SiO_(2) multilayers.Compared with phosphorous singly doped Si nanocrystals,it is interesting to find that the concentration of phosphorous in co-doped samples can be significantly improved.Theoretical simulation suggests that phosphorous-boron pairs are formed in co-doped Si nanocrystals with the lowest formation energy,which also reduces the formation energy of phosphorous in Si nanocrystals.The results indicate that co-doping can promote the entry of phosphorous impurities into the near-surface and inner sites of Si nanocrystals,which provides an interesting way to regulate the electronic and optical properties of Si nanocrystals such as the observed enhancement of conductivity and sub-band light emission.

Improving the electrocatalytic activity of Fe,N co-doped biochar for polysulfide by regulation of N-C and Fe-N-C electronic configurations

The conversion of agricultural residual biomass into biochar as a sulfur host material for Li-S batteries is a promising approach to alleviate the greenhouse effect and realize waste resource reutilization.However,the large-scale application of pristine biochar is hindered by its low electrical conductivity and limited electrocatalytic sites.This paper addressed these challenges via the construction of Fe-N co-doped biochar(Fe-NOPC)through the copyrolysis of sesame seeds shell and ferric sodium ethylenediaminetetraacetic acid(NaFeEDTA).During the synthesis process,NaFeEDTA was used as an extra carbon resource to regulate the chemical environment of N doping,which resulted in the production of high contents of graphitic,pyridinic,and pyrrolic N and Fe-Nx bonds.When the resulting Fe-NOPC was used as a sulfur host,the pyridinic and pyrrolic N would adjust the surface electron structure of biochar to accelerate the electron/ion transport,and the electropositive graphitic N could be combined with sulfur-related species via electrostatic attraction.Fe-Nx could also promote the redox reaction of lithium polysulfides due to the strong Li-N and S-Fe bonds.Benefiting from these advantages,the resultant Fe-NOPC/S cathode with a sulfur loading of 3.8 mg·cm^(-2)delivered an areal capacity of 4.45 mAh·cm^(-2)at 0.1C and retained a capacity of 3.45 mAh·cm^(-2)at 1C.Thus,this cathode material holds enormous potential for achieving energy-dense Li-S batteries.

Microbial synthesis of N, P co-doped carbon supported PtCu catalysts for oxygen reduction reaction

Developing highly efficient and stable platinum-based electrocatalyst for oxygen reduction reaction(ORR) is critical to expediting commercialization of fuel cells.Herein,several PtCu alloy nanocatalysts supported on N,P co-doped carbon(PtCu/NPC) were prepared by microbial-sorption and carbonization-reduction.Among them,PtCu/NPC-700 ℃ exhibits excellent catalytic performance for ORR with a mass activity of 0.895 A mg_(pt)^(-1)(@0.9 V) which is 8.29 folds of commercial Pt/C.Additionally,the ECSA and MA of PtCu/NPC-700℃ only decrease by 14.2% and 18.7% respectively,while Pt/C decreases by 35.2% and 52.8% after 10,000 cycles of ADT test.Moreover,the PtCu/NPC-700℃ catalyst emanates a maximum power density of 715 mW cm^(-2) and only 11.1% loss of maximum power density after 10,000 ADTs in single-cell test,indicating PtCu/NPC-700℃ also manifests higher activity and durability in actual single-cell operation than Pt/C.This research provides an easy and novel strategy for developing highly active and durable Pt-based alloy catalyst.

Nitrogen and phosphorus co-doped activated carbon induces high density Cu^(+)active center for acetylene hydrochlorination

This work aims to solve the problems of low reaction activity of Cu-based catalysts and agglomeration of active centers in acetylene hydrochlorination.Cu-based catalysts supported by NAP co-doped activated carbon(AC)with different content(mCu-xNP/AC)were manufactured and applied in the acetylene hydrochlorination reaction.It was found that the doping of carriers N and P induced the transformation of Cu^(2+)to Cu^(+),and the catalytic activity was markedly improved.Under the optimal reaction temperature of 220℃,the gas hourly space velocity(GHSV)of C_(2)H_(2)was 90 h^(-1)and V_(HCl):V_(C_(2)H_(2))was 1.15.The initial activity of the 5%Cu-30 NP/AC catalyst reached 95.59%.Through some characterization methods showed the addition of N and P improved the dispersion of Cu in carbon,which increased the ratio of Cu^+/Cu^(2+).The measurement results confirmed that the chemisorption capacity of mCu-xNP/AC for C_(2)H_(2)decreased slightly,and the chemisorption capacity for HCl increased significantly,which was the reason for the increased activity of the catalyst.The conclusion provides a reference for the development of acetylene hydrochlorination Cu catalyst.

Regulating interfacial chemistry and kinetic behaviors of F/Mo co-doping Ni-rich layered oxide cathode for long-cycling lithium-ion batteries over-20°C-60°C

Ni-rich layered oxide cathodes have shown promise for high-energy lithium-ion batteries(LIBs)but are usually limited to mild environments because of their rapid performance degradation under extreme temperature conditions(below0°C and above 50 °C).Here,we report the design of F/Mo co-doped LiNi_(0.8)Co_(0.1)Mn_(0.1)O_(2)(FMNCM)cathode for high-performance LIBs from-20 to 60°C.F^(-) doping with high electronegativity into the cathode surface is found to enhance the stability of surface lattice structure and protect the interface from side reactions with the electrolyte by generating a LiF-rich surface layer.Concurrently,the Mo^(6+) doping suppresses phase transition,which blocks Li^(+)/Ni^(2+) mixing,and stabilizes lithium-ion diffusion pathway.Remarkably,the FMNCM cathode demonstrates excellent cycling stability at a high cutoff voltage of 4.4 V,even at 60°C,maintaining 90.6%capacity retention at 3 C after 150 cycles.Additionally,at temperatures as low as-20°C,it retains 77.1%of its room temperature capacity,achieving an impressive 97.5%capacity retention after 500 cycles.Such stable operation under wide temperatures has been further validated in practical Ah-level pouch-cells.This study sheds light on both fundamental mechanisms and practical implications for the design of advanced cathode materials for wide-temperature LIBs,presenting a promising path towards high-energy and long-cycling LIBs with temperatureadaptability.

Improved Corrosion Behavior of Biodegradable Mg-4Zn-1Mn Alloy Modified by Sr/F co-doped CaP Micro-arc Oxidation Coatings

The Sr/F co-doped CaP(Sr/F-CaP)coatings were prepared by micro-arc oxidation(MAO)under different voltages to modify the microstructure and corrosion behavior of Mg-4Zn-1Mn alloy.The surface and interface characteristics investigated using scanning electron microscopy(SEM)and energy dispersive X-ray spectrometer(EDS)showed that the MAO coatings displayed uneven crater-like holes and tiny cracks under lower voltage,while they exhibited relatively homogeneous crater-like holes without cracks under higher voltage.The thickness of MAO coatings increased with increasing voltage.The corrosion behavior of Mg-4Zn-1Mn alloy was improved by the MAO coatings.The MAO coatings prepared under 450 V and 500 V voltages possessed the best corrosion resistance with regard to the electrochemical corrosion tests and immersion corrosion tests,respectively.The MAO coatings fabricated under 450-500 V could provide a better corrosion protection effect for the substrate.

Preparation, Characterization and Photocatalytic Activity of Fe, La Co-doped Nanometer Titanium Dioxide Photocatalysts

A series of photocatalysts of un-doped, single-doped and co-doped nanometer titanium diox- ide （TiO2） have been successfully prepared by template method using Fe（NO3）3.9H2O, La（NO3）3.6H2O, and tetrabutyl titanate as precursors and glucan as template. Scanning electron microscopy, X-ray diffraction, and N2 adsorption-desorption measurement were employed to characterize the morphology, crystal structure and surface structure of the samples. The photo-absorbance of the obtained catalysts was measured by UV-Vis absorption spectroscopy, and the photocatalytic activities of the prepared samples under UV and visible light were estimated by measuring the degradation rate of methyl orange in an aqueous solution. The characterizations indicated that the prepared photocatalysts consisted of anatase phase and possessed high surface area of ca. 163-176 m2/g. It was shown that the Fe and La co-doped nano-TiO2 could be activated by visible light and could thus be used as an effective catalyst in photo-oxidation reactions. The synergistic effect of Fe and La co-doping played an important role in improving the photocatalytic activity. In addition, the possibility of cyclic usage of co-doped nano-TiO2 was also confirmed, the photocatalytic activity of codoped nano-TiO2 remained above 89.6% of the fresh sample after being used four times.

Preparation, Characterization, Photocatalytic Activity of S and Ag co-Doped Mesoporous Titania Photocatalysts

In order to improve the photocatalytic performance of mesoporous titania under visible light, a series of photocatalysts of S and Ag co-doped mesoporous titania have been successfully prepared by template method using thiourea, AgNO3 and tetrabutyl titanate as precursors and Pluronic P123 （EO20PO70EO20） as template. Scanning electron microscopy （SEM）, X-ray diffraction （XRD）, nitrogen adsorption-desorption measurements, and UV-visible spectroscopy （UV-Vis） were employed to characterize the morphology, crystal structure, surface structure, and optical absorption properties of the samples. The microcrystal of the photocatalysts consisted of anatase phase and was approximately present in the form of spherical particle. The photocatalytic performance was studied by photodegradation methyl orange （MO） in water under UV and visible light irradiation. The calcination temperature and the doping content influenced the photoactivity. In addition, the possibility of cyclic usage of co-doped mesoporous titania was also confirmed, the photocatalytic activity of mesoporous titania remained above 89% of that of the fresh sample after being used four times. It was shown that the co-doped mesoporous titania could be activated by visible light and could thus be potentially applied for the treatment of water contaminated by organic pollutants. The synergistic effect of sulfur and silver co-doping played an important role in improving the photocatalytic activity.

Visible light induced photodegradation of organic pollutants on nitrogen and fluorine co-doped TiO_2 photocatalyst

The nitrogen and fluorine co doped TiO 2 polycrystalline powder was synthesized by calcinations of the hydrolysis product of tetra butyl titanate with ammonium fluoride. Nitrogen and fluorine co doping causes the absorption edge of TiO 2 to shift to a lower energy region. The photocatalytic activity of co doped TiO 2 with anatase phases was found to be 2 4 times higher than that of the commercial TiO 2 photocatalyst Degussa P25 for phenol decomposition under visible light irradiation. The co doped TiO 2 powders only contain anatase phases even at 1000℃. Apparently, ammonium fluoride added retarded phase transformation of the TiO 2 powders from anatase to rutile. The substitutional fluorine and interstitial nitrogen atoms in co doped TiO 2 polycrystalline powder were responsible for the vis light response and caused the absorption edge of TiO 2 to shift to a lower energy region.

Synthesis and Characterization of Co-Doped Brookite Titania Photocatalysts with High Photocatalytic Activity

Transition metal-doping could effectively extend the light response range of TiO _2 photocatalysts from the ultraviolet(UV)to the visible region.Co-doped brookite titanium dioxide(Co–TiO_2)photocatalysts were synthesized via the hydrothermal method with titanium tetrachloride as the raw material and cobalt chloride hexahydrate as the dopant.The prepared Co–TiO_2 photocatalysts were characterized by X-ray diffraction(XRD),scanning electron microscopy(SEM),transmission electron microscopy(TEM),Raman spectroscopy,X-ray photoelectron spectroscopy(XPS)and UV–Vis diffuse reflectance spectroscopy(UV–Vis DRS).The photocatalytic activities of Co–TiO _2 photocatalysts were evaluated by photocatalytic degradation of isopropanol alcohol(IPA),a typical volatile organic compound(VOC),under visible light.The influences ofdifferent Co doping rates,initial concentrations of IPA gas and the amounts of photocatalyst addition were also studied.At the same time,the enhancement mechanism ofcobalt ions as a trap for photogenerated holes was discussed.Thus,we found the optimum doping rate,initial concentration of IPA gas and amount of photocatalyst to add.The results show that the mesoporous Co–TiO _2 photocatalysts possess smaller size particles,larger specific surface area,lower forbidden bandgap energy(Eg)and better photocatalytic activity than pure brookite TiO _2.When the doping of Co was 7% by mass,the initial concentration ofIPA gas was 1.0×10^(-6 )mol/L and the addition of Co–TiO_2 photocatalysts was 50 mg,the best photocatalytic activity was achieved.Furthermore,the degradation rate ofIPA was up to 91%,which shows great potential for waste water treatment.

Preparation of nitrogen and sulfur co-doped ultrathin graphitic carbon via annealing bagasse lignin as potential electrocatalyst towards oxygen reduction reaction in alkaline and acid media

Renewable lignin used for synthesizing materials has been proven to be highly potential in specific electrochemistry.Here,we report a simple method to synthesize nitrogen and sulfur co-doped carbon nanosheets by using bagasse lignin,denoted as lignin-derived carbon(LC).By adjusting the ratio of nitrogen source and annealing temperature,we obtained the ultrathin graphitic lignin carbon(LC-4-1000)with abundant wrinkles with high surface area of 1208 m2g_1 and large pore volume of 1.40 cm3g_1.In alkaline medium,LC-4-1000 has more positive half-wave potential and nearly current density compared to commercial Pt/C for oxygen reduction reaction(ORR).More importantly,LC-4-1000 also exhibits comparable activity and superior stability for ORR in acid medium due to its high graphitic N ratio and a direct four electron pathway for ORR.This study develops a cost-effective and highly efficient method to prepare biocarbon catalyst for ORR in fuel cells.

Difference in magnetic properties between Co-doped ZnO powder and thin film

This paper reports that the Zn0.95Co0.05O polycrystalline powder and thin film were prepared by sol-gel technique under the similar preparation conditions. The former does not show typical ferromagnetic behaviour, while the latter exhibits obvious ferromagnetic properties at 5 K and room temperature. The UV-vis spectra and x-ray absorption spectra show that Co2＋ ions are homogeneously incorporated into ZnO lattice without forming secondary phases.The distinct difference between film and powder sample is the c-axis （002） preferential orientation indicated by the x-ray diffraction pattern and field emission scanning electron microscopy measurement, which may be the reason why Zn0.95Co0.05O film shows ferromagnetic behaviour.

Enhanced photocatalytic activity of (La, N) co-doped TiO_2 by TiCl_4 sol-gel autoigniting synthesis

（La, N） co-doped TiO2 photocatalysts were synthesized using TiC14 sol-gel autoignidng synthesis （SAS） starting from a complex compound system of TiCl4-La（NO3）3-citric acid-NH4NO3-NHyH2O, in which the （La, N） co-doped process was accompushed in the formation of TiO2 nanocrystals. The prepared samples were characterized by using X-ray diffraction （XRD）, X-ray photoemission spectroscopy （XPS） and UV-vis diffuse reflectance spectra. The results indicated that nitrogen and lanthanum were incorporated into the lattice and interstices of titania nanocrystals, which resulted in narrowing the band gap and promoting the separation of photoexcited hole-electron pairs, respectively, and showing expected red-shifts and enhanced photocatalytic activity under visible light. The mechanism on nitrogen doping and enhancement in photocatalyfic activity of （La, N） co-doped titania by SAS was discussed in detail.

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.

Photocatalytic Activity of Lanthanum and Sulfur Co-doped TiO_2 Photocatalyst under Visible Light

A novel lanthanum and sulfur co-doped TiO2 photocatalyst was synthesized by precipitation- dipping method, and characterized by X-ray diffraction（XRD）, transmission electron microscopy（TEM） and UV-Vis diffuse reflectance spectroscopy. Compared with the S-doped TiO, La-doped TiO2 and the standard Degussa P25 photocatalysts, the lanthanum and sulfur co-doped TiO2 photocatalyst （the molar percentage of La is 3.0%） calcined at 450 ℃ for 2 h showed the strongest absorption for visible light and highest activities for degradation of reactive blue 19 dye in aqueous solution under visible light（λ〉400 nm） irradiation. It was also discovered that the co-doping of lanthanum and sulfur hindered the aggregation and growth of TiO2 particles, and the doping of lanthanum reduced slightly the phase transition temperature ofTiO2 from anatase to rutile.

Hierarchical sulfur and nitrogen co-doped carbon nanocages as efficient bifunctional oxygen electrocatalysts for rechargeable Zn-air battery

Exploring inexpensive and efficient bifunctional electrocatalysts for oxygen reduction reaction(ORR) and oxygen evolution reaction(OER) is critical for rechargeable metal-air batteries. Herein, we report a new 3D hierarchical sulfur and nitrogen co-doped carbon nanocages(hSNCNC) as a promising bifunctional oxygen electrocatalyst by an in-situ MgO template method with pyridine and thiophene as the mixed precursor. The as-prepared h SNCNC exhibits a positive half-wave potential of 0.792 V(vs. reversible hydrogen electrode, RHE) for ORR, and a low operating potential of 1.640 V at a 10 mA cm-2 current density for OER. The reversible oxygen electrode index is 0.847 V, far superior to commercial Pt/C and IrO2,which reaches the top level of the reported bifunctional catalysts. Consequently, the hSNCNC as air cathodes in an assembled Zn-air battery features low charge/discharge overpotential and long lifetime. The remarkable properties arises from the introduced multiple heteroatom dopants and stable 3D hierarchical structure with multi-scale pores, which provides the abundant uniform high-active S and N species and efficient charge transfer as well as mass transportation. These results demonstrate the potential strategy in developing suitable carbon-based bi-/multi-functional catalysts to enable the next generation of the rechargeable metal-air batteries.