An approach was presented for synthesis of semiconducting single-walled carbon nanotubes(SWNTs) by sulfur(S) doping with the method of graphite arc discharge. Raman spectroscopy, UV-vis-NIR absorption spectroscopy and...An approach was presented for synthesis of semiconducting single-walled carbon nanotubes(SWNTs) by sulfur(S) doping with the method of graphite arc discharge. Raman spectroscopy, UV-vis-NIR absorption spectroscopy and electronic properties measurements indicated the semconducting properties of the SWNTs samples. Simulant calculation indicated that S doping could induce convertion of metallic SWNTs into semiconducting ones. This strategy may pave a way for the direct synthesis of pure semiconducting SWNTs.展开更多
Metal-nitrogen-carbon materials are promising catalysts for CO2 electroreduction to CO. Herein, by taking the unique hierarchical carbon nanocages as the support, an advanced nickel-nitrogen-carbon single-site catalys...Metal-nitrogen-carbon materials are promising catalysts for CO2 electroreduction to CO. Herein, by taking the unique hierarchical carbon nanocages as the support, an advanced nickel-nitrogen-carbon single-site catalyst is conveniently prepared by pyrolyzing the mixture of NiCl2 and phenanthroline, which exhibits a Faradaic efficiency plateau of > 87% in a wide potential window of −0.6 – −1.0 V. Further S-doping by adding KSCN into the precursor much enhances the CO specific current density by 68%, up to 37.5 A·g−1 at −0.8 V, along with an improved CO Faradaic efficiency plateau of > 90%. Such an enhancement can be ascribed to the facilitated CO pathway and suppressed hydrogen evolution from thermodynamic viewpoint as well as the increased electroactive surface area and improved charge transfer fromkinetic viewpoint due to the S-doping. This study demonstrates a simple and effective approach to advanced electrocatalysts by synergetic modification of the porous carbon-based support and electronic structure of the active sites.展开更多
Several nanoporous Fe2 O3-xSx/S-doped g-C3 N4（CNS） Z-scheme hybrid heterojuctions have been successfully synthesized by one-pot in situ growth of the Fe2O3-xSx particles on the surface of CNS. The characterization r...Several nanoporous Fe2 O3-xSx/S-doped g-C3 N4（CNS） Z-scheme hybrid heterojuctions have been successfully synthesized by one-pot in situ growth of the Fe2O3-xSx particles on the surface of CNS. The characterization results show that S-doping in the g-C3 N4 backbone can greatly enhance the charge mobility and visible light harvesting capability. In addition, porous morphology of hybrid composite provides available open pores for vip molecules and also improves light absorbing property due to existence of multiple scattering effects. More importantly, the Fe2 O3-xSx nanoparticles formed intimate heterojunction with CNS and developed the efficient charge transfer by extending interfacial interactions occurred at the interfaces of both components. It has been found that the Fe2 O3-xSx/CNS composites have an enhanced photocatalytic activity under visible light irradiation compared with isolated Fe2 O3 and CNS components toward the photocatalytic degradation of methylene blue（MB）. The optimal loaded Fe2 O3-xSx value obtained is equal to 6.6 wt% that provided 82% MB photodegradation after 150 min with a reaction rate constant of 0.0092 min（-1） which was faster than those of the pure Fe2 O3（0.0016 min（-1））and CNS（0.0044 min（-1）） under the optimized operating variables acquired by the response surface methodology. The specific surface area and the pore volume of Fe2 O3（6.6）/CNS hybrid are 33.5 m2/g and0.195 cm3/g, which are nearly 3.8 and 7.5 times greater compared with those of the CNS, respectively. The TEM image of Fe2 O3（6.6）/CNS nanocomposite exhibits a nanoporous morphology with abundant uniform pore sizes of around 25 nm. Using the Mott-Schottky plot, the conduction and valence bands of the CNS are measured（at pH = 7） equal to-1.07 and 1.48 V versus normal hydrogen electrode（NHE）, respectively.Trapping tests prove that ·OH-and ·O2-radicals are major active species in the photocatalytic reaction.It has been established that formation of the Z-scheme Fe2 O3（6.6）/CNS heterojunction between CNS and Fe2 O3 directly produces ·OH as well as ·O2-radicals which is consistent with the results obtained from trapping experiments.展开更多
Metal selenides have been explored as promising sodium storage materials owing to their high theoretical capacity.However,sluggish Naþdiffusion and low electronic conductivity of selenides still hinder their prac...Metal selenides have been explored as promising sodium storage materials owing to their high theoretical capacity.However,sluggish Naþdiffusion and low electronic conductivity of selenides still hinder their practical applications.Herein,FeSe_(2-x)S_(x)microspheres have been prepared via a self-doping solvothermal method using NH4Fe(SO4)2 as both the Fe and S source,followed by gas phase selenization.The density functional theory calculation results reveal that S doping not only improves the Na adsorption,but also lower the diffusion energy barrier of Na atoms at the S doping sites,at the same time enhance the electronic conductivity of FeSe_(2-x)S_(x).The carbon-free nature of the FeSe_(2-x)S_(x)microspheres results in a low specific surface area and a high tap density,leading to an initial columbic efficiency of 85.6%.Compared with pure FeSe_(2),such FeSe_(2-x)S_(x)delivers a high reversible capacity of 373.6 mAh⋅g^(-1)at a high current density of 5 A⋅g^(-1)after 2000 cycles and an enhanced rate performance of 305.8 mAh⋅g^(-1)at even 50 A⋅g1.Finally,the FeSe_(2-x)S_(x)//NVP pouch cells have been assembled,achieving high energy and volumetric energy densities of 118 Wh⋅kg1 and 272 mWh⋅cm3,respectively,confirming the potential of applications for the FeSe_(2-x)S_(x)microspheres.展开更多
Photocatalysis using the abundant solar energy is an environmentally friendly and efficient way to degrade organic matter.Covalent triazine frameworks(CTFs),a new class of metal-free organic semiconductors responsive ...Photocatalysis using the abundant solar energy is an environmentally friendly and efficient way to degrade organic matter.Covalent triazine frameworks(CTFs),a new class of metal-free organic semiconductors responsive to visible light,are promising materials for water treatment.In this study,an original CTF,namely CTF-1,was modified by S-doping to form CTFSx,which were used as metal-free catalysts for degradation of methyl orange(MO)and bisphenol A(BPA).The outcomes demonstrated that the photocatalytic degradation of MO and BPA by CTFSxwas superior to that by CTF-1,with better stability and reusability.Within 6 h,53.2%MO and 84.7%BPA were degraded by CTFS5,and the degradation rate constants were 0.145 h-1and 0.29 h-1,respectively,which were 3.6 and 5.8 times higher than those of CTF-1.Further investigation revealed that enhanced visible light absorption,a reduced degree of free carrier recombination,rapid separation and transfer of photogenerated electrons and holes,and improved·OH oxidation capacity were important factors contributing to the significantly enhanced photocatalytic activity.The S-doping method effectively improved the light absorption performance,electronic structure,and modulation band structure of CTF-1.This work highlights the potential application of low-cost metal-free catalysts driven by visible light for the removal of organic pollutants from wastewater.展开更多
Na-ion batteries(NIBs)have attracted considerable attention in recent years owing to the high abundance and low cost of Na.It is well known that S doping can improve the electrochemical performance of carbon materials...Na-ion batteries(NIBs)have attracted considerable attention in recent years owing to the high abundance and low cost of Na.It is well known that S doping can improve the electrochemical performance of carbon materials for NIBs.However,the current methods for S doping in carbons normally involve toxic precursors or rigorous conditions.In this work,we report a creative and facile strategy for preparing S-doped porous carbons(SCs)via the pyrolysis of conjugated microporous polymers(CMPs).Briefly,thiophene-based CMPs served as the precursors and doping sources simultaneously.Simple direct carbonization of CMPs produced S-doped carbon materials with highly porous structures.When used as an anode for NIBs,the SCs exhibited a high reversible capacity of 440 mAh g?1 at 50 mA g?1 after 100 cycles,superior rate capability,and excellent cycling stability(297 mAh g?1 after 1000 cycles at 500 mA g?1),outperforming most S-doped carbon materials reported thus far.The excellent performance of the SCs is attributed to the expanded lattice distance after S doping.Furthermore,we employed ex situ X-ray photoelectron spectroscopy to investigate the electrochemical reaction mechanism of the SCs during sodiation-desodiation,which can highlight the role of doped S for Na-ion storage.展开更多
In this work,a simple synthesis of sulfur doped graphitic carbon nitride(S-g-C3N4)act as a support cum stabilizers for gold nanoparticles(Au)and its was characterized by UV–vis and XRD to measure the absorbance and c...In this work,a simple synthesis of sulfur doped graphitic carbon nitride(S-g-C3N4)act as a support cum stabilizers for gold nanoparticles(Au)and its was characterized by UV–vis and XRD to measure the absorbance and crystallinity,respectively.The functional group and morphology of the samples were identified using FT-IR and TEM.Finally,the Au@S-g-C3N4 nanocatalyst exhibits good catalytic performance and stability in the reduction of hazardous 4-nitrophenol(NP)compared to S-g-C3N4 using Na BH4.Moreover,the Au@S-g-C3N4 nanocomposite holds a good catalytic efficiency(near 100%)achieved by within 5 min.The highest catalytic reduction of NP is due to the synergistic effect of Au nanoparticles decorated on S-g-C3N4.The fast electron transfer reduction mechanism was elucidated and discussed.Excellent reusability and stability of the developed nanocomposites were also observed in consecutive reduction experiments.The filtering and catalyzing device was used for the direct conversion of NP polluted water.This method can open a new avenue for the metal nanoparticles based carbon materials heterogeneous catalyst and its reduction of toxic contaminants.展开更多
Titanium dioxide(TiO_2) has been investigated broadly as a stable,safe,and cheap anode material for sodium-ion batteries in recent years.However,the poor electronic conductivity and inherent sluggish sodium ion diffus...Titanium dioxide(TiO_2) has been investigated broadly as a stable,safe,and cheap anode material for sodium-ion batteries in recent years.However,the poor electronic conductivity and inherent sluggish sodium ion diffusion hinder its practical applications.Herein,a self-template and in situ vulcanization strategy is developed to synthesize self-supported hybrid nanotube arrays composed of nitrogen/sulfur-codoped carbon coated sulfur-doped TiO_2 nanotubes(S-TiO_2@NS-C) starting from H_2 Ti_2 O_5-H_2 O nanoarrays.The S-TiO_2@NS-C composite with one-dimensional nano-sized subunits integrates several merits.Specifically,sulfur doping strongly improves the Na~+ storage ability of TiO_2@C-N nanotubes by narrowing the bandgap of original TiO_2.Originating from the nanoarrays structures built from hollow nanotubes,carbon layer and sulfur doping,the sluggish Na~+ insertion/extraction kinetics is effectively improved and the volume variation of the electrode material is significantly alleviated.As a result,the S-TiO_2@NS-C nanoarrays present efficient sodium storage properties.The greatly improved sodium storage performances of S-TiO_2@NS-C nanoarrays confirm the importance of rational engineering and synthesis of hollow array architectures with higher complexity.展开更多
In this study, S-doped NbSea （NbSo.aSel.8） powders were fabricated, and the corresponding Cu-based composites （Cu/NbSo.eSe1.8） were obtained by powder metallurgy technique. The phase compositions, physical, and tr...In this study, S-doped NbSea （NbSo.aSel.8） powders were fabricated, and the corresponding Cu-based composites （Cu/NbSo.eSe1.8） were obtained by powder metallurgy technique. The phase compositions, physical, and tribological properties of Cu-based composites were investigated systematically. The results show that Cu matrix reacts with NbSo.2Sel.8 to produce Cu2Se and Cu0.38NbSo.2Se1.8 during sintering process, which influences the physical and tribological properties of Cu-based composites significantly. Specially, with NbS0.2Se1.8 content increasing, the density of Cu/ NbSo.2Se1.8 composites decreases, and the hardness increases firstly and then decreases, while the electric resistivity in- creases slightly. In addition, the incorporation of NbSo.2Se1.8 enhances the tribological properties of Cu greatly, which is attributed to the lubricating effect of Cuo,38NbSo.2Se1.8 and the reinforcement effect of Cu2Se. In particular, when the content of NbSo.2Sel.8 is 6 wt%, the Cu-based composite has the best tribological properties.展开更多
The orientation construction of S-doped porous carbon fibers(SPCFs)is realized by the facile template-directed methodology using asphalt powder as carbon source.The unique fiber-like morphology without destruction can...The orientation construction of S-doped porous carbon fibers(SPCFs)is realized by the facile template-directed methodology using asphalt powder as carbon source.The unique fiber-like morphology without destruction can be well duplicated from the template by the developed methodology.MgSO4 fibers serve as both templates and S dopant,realizing the in-situ S doping into carbon frameworks.The effects of different reaction temperatures on the yield and S doping level of SPCFs are investigated.The S doping can not only significantly enhance the electrical conductivity,but also introduce more defects or disorders.As anode material for lithium ion batteries(LIBs),SPCFs electrode delivers better rate capability than undoped PCFs.And the capacity of SPCFs electrode retains around 90%after 300 cycles at 2 A g1,exhibiting good cycling stability.As the electrocatalysts for fuel cells,the onset potentials of SPCFs obtained at 800 and 900C are concentrated at 0.863 V,and the higher kinetic current densities at 0.4 V of them are larger than that of PCFs,demonstrating the superior electrocatalytic performance.Due to the synergistic effect of abundant pore channels and S doping,SPCFs electrode exhibits superior electrochemical performances as anode for LIBs and elecctrocatalyst for fuel cells,respectively.Additionally,the oriented conversion of asphalt powder into high-performance electrode material in this work provides a new way for the high value application of asphalt.展开更多
Alkaline hydrogen evolution reaction (HER) suffers from a sluggish kinetic,which requires the elaborate catalytic interface and micro-nanoscale architecture engineering of the electrocatalysts to accelerate the water ...Alkaline hydrogen evolution reaction (HER) suffers from a sluggish kinetic,which requires the elaborate catalytic interface and micro-nanoscale architecture engineering of the electrocatalysts to accelerate the water dissociation and hydrogen evolution.Herein,the heterointerface engineering was proposed for promoting the alkaline HER by constructing the highly exposed Ru/RuS_(2) heterostructures homogeneously distributed on hollow N/S-doped carbon microspheres (Ru/RuS_(2)@h-NSC).Benefited from the synergistic effect of heterointerfacial Ru/RuS_(2),the high accessibility of the active sites on both inner and outer surface of mesoporous shells and the efficient mass transport,Ru/RuS_(2)@h-NSC affords a remarkable catalytic performance with an overpotential of 26 mV@10 mA/cm^(2) for alkaline HER,outperforming most of the state-of-the-art catalysts.Further applying Ru/RuS_(2)@h-NSC and its oxidized derivate for the overall alkaline water splitting,the required cell voltage is much lower than that of the commercial Pt/C||RuO_(2)pair to achieve the same current density.Our study may allow us to guide the design of micro-nanoreactors with optimal catalytic interfaces for promising electrocatalytic applications.展开更多
Superior bifunctional electrocatalysts with ultra-high stability and excellent efficiency are crucial to boost the oxygen evolution reaction(OER) and the hydrogen evolution reduction(HER) in the overall water splittin...Superior bifunctional electrocatalysts with ultra-high stability and excellent efficiency are crucial to boost the oxygen evolution reaction(OER) and the hydrogen evolution reduction(HER) in the overall water splitting(OWS) for the sustainable production of clean fuels. Herein, comprehensive density functional theory(DFT) computations were performed to explore the potential of several single transition metal(TM) atoms anchored on various S-doped black phosphorenes(TM/Snx-BP) for bifunctional OWS electrocatalysis. The results revealed that these candidates display good stability, excellent electrical conductivity, and diverse spin moments. Furthermore, the Rh/S12-BP catalyst was identified as an eligible bifunctional catalyst for OWS process due to the low overpotentials for OER(0.43 V) and HER(0.02 V), in which Rh and its adjacent P atoms were identified as the active sites. Based on the computed Gibbs free energies of OH~*, O~*, OOH~* and H~*, the corresponding volcano plots for OER and HER were established.Interestingly, the spin moments and the charge distribution of the active sites determine the catalytic trends of OER and HER. Our findings not only propose a promising bifunctional catalyst for OWS, but also widen the potential application of BP in electrocatalysis.展开更多
Graphene quantum dots （GODs） recently emerge as the new and appealing nanophotocatalyst because of their low-cost, environmental compatibility and the ability to facilitate the charge migration and prolong the charg...Graphene quantum dots （GODs） recently emerge as the new and appealing nanophotocatalyst because of their low-cost, environmental compatibility and the ability to facilitate the charge migration and prolong the charge lifetimes. In this work, a visible photocatalyst of S-doped graphene quantum dots （S-GQDs） was prepared by a facile hydrothermal synthesis using 1,3,6-trinitropyrene and Na2S as precursors. The well crystallization and monodispersity as well as the chemical environment of S-GQDs were characterized by transmission electron microscopy, atom force microscopy and X-ray photoelectron spectrum. A superior photocatalytic performance of S-GQDs was demonstrated for degradation of basic fuchsin under visible light irradiation. Furthermore, the possible photocatalytic mechanism was proposed based on the trapping experiments of active species.展开更多
S-doped Sb_2O_3 nanocrystals were synthesized using SbCl3 and thioacetamide（TAA） as starting materials by a hydrothermal method and the effects of TAA dosage on the composition and properties of resultant nanocrysta...S-doped Sb_2O_3 nanocrystals were synthesized using SbCl3 and thioacetamide（TAA） as starting materials by a hydrothermal method and the effects of TAA dosage on the composition and properties of resultant nanocrystals were determined.Their photocatalytic performance was evaluated using the degradation of methyl orange（MO） as a model reaction.The results suggest that TAA dosage can affect the preferential growth direction of Sb_2O_3,and further influences its photocatalytic activity.S doping can extend the optical absorption edge of Sb_2O_3 to the visible light religion,and thus endows its ability to photocatalyze the degradation of MO under visible light illumination.Based on these results,the correlations between the photocatalytic activity of S-doped Sb_2O_3 and the ratio between exposed facets,specific surface area and crystallographic defects were discussed.展开更多
Bismuth(Bi)anodes have been widely investigated for potential application in sodium-ion batteries(SIBs)due to their ultrahigh theoretical volumetric capacity(3800 mAh cm^(-3))and suitable sodiation potential(0.5-0.7 V...Bismuth(Bi)anodes have been widely investigated for potential application in sodium-ion batteries(SIBs)due to their ultrahigh theoretical volumetric capacity(3800 mAh cm^(-3))and suitable sodiation potential(0.5-0.7 V).Unfortunately,either Bi or Bi-based compounds still face tricky challenges of unsatisfying reversible capacity(<350 mAh g^(-1))and inferior initial Coulombic efficiency(ICE,<70%).Herein,a controllable trace-sulfurization strategy is proposed to address these challenges by developing a yolkshell Bi/Bi_(2)S_(3)heterostructure encapsulated within S-doped carbon shells(TS-Bi/C).This approach strategically incorporates a trace amount of high-capacity Bi_(2)S_(3)phase with metallic Bi,consequently building regional Bi/Bi_(2)S_(3)heterointerfaces for enhancing interfacial charge transfer and sodium storage reversibility.Moreover,a thin and homogeneous solid electrolyte film(~5 nm)was formed on the surface of TS-Bi/C during the initial discharge-charge process.These merits result in an approximate 30%increase in ICE of TS-Bi/C(87.4%)compared to pure Bi/C(57,6%)when employed as anodes in SIBs,together with boosted discharge capacity of 462.3 mAh g^(-1)at 0.1 A g^(-1)and high rate capability of 382.4 mAh g^(-1)at 10 A g^(-1).Importantly,as compared to both Bi/C and Bi_(2)S_(3)/C counterparts,TS-Bi/C can deliver superior volumetric capacity as high as 1553 mAh cm^(-3)owing to its considerable tap density of 3.43 g cm^(-3).展开更多
Heterojunctions constructed by traditional methods often result in random stacking of materials, leading to lattice mismatch, which adversely affects the extraction and transfer of photo-generated carriers and, in tur...Heterojunctions constructed by traditional methods often result in random stacking of materials, leading to lattice mismatch, which adversely affects the extraction and transfer of photo-generated carriers and, in turn, hampers light utilization efficiency. In this work, we report a novel heterojunction comprising alternating S-doped g-C_(3)N_(4) (SCN) and N-doped MoS_(2) (NMS), bridged by Mo–N covalent bonds within hierarchical periodic macroporous (HPM) walls. This heterojunction is synthesized by co-pyrolyzing dicyandiamide, thiourea, and ammonium molybdate. Transient reflectance photoluminescence measurements reveal that the Mo–N covalent bonds serve as “fast tracks” for electron transfer from SCN to NMS, significantly enhancing the charge separation efficiency. Additionally, the well-defined spatial separation of photo-induced carriers, coupled with the efficient mass transfer within the HPM structure, promotes superior carrier utilization. Thanks to the synergistic effect of HPM structures and the bridged Mo–N bonds, the optimized HPM NMS/SCN-1.3 sample exhibits a remarkable H_(2) evolution rate of 473.3 µmol g^(−1) h^(−1) under visible light irradiation, which is approximately 163 and 19 times higher than bulk g-C_(3)N_(4) (BCN) and HPM SCN, respectively. This work offers valuable insights into the design of HPM heterojunctions composed of co-catalysts and host catalysts, paving the way for enhanced photocatalytic H₂ evolution.展开更多
The rational fabrication of an efficient heterojunction is critical to the enhancement of photocatalytic hydrogen(H_(2)) evolution performance.Herein,a new-fashioned graphitic-carbon nitride(g-C_(3) N_(4)) based isoty...The rational fabrication of an efficient heterojunction is critical to the enhancement of photocatalytic hydrogen(H_(2)) evolution performance.Herein,a new-fashioned graphitic-carbon nitride(g-C_(3) N_(4)) based isotype step-scheme(S-scheme) heterojunction composed of sulfur-doped and sulfur-free active sites is developed by liquid sulfur-mediation of exfoliated g-C_(3) N_(4).Particularly,the liquid sulfur not only contributes to the full contact between sulfur species and exfoliated g-C_(3) N_(4),but also creates sulfur-doping and abundant pores,since self-gas foaming effect of sulfur vapor.Moreover,the S-doped and S-free active sites located in the structural unit of C_(3) N_(4) jointly construct a typical sulfur-doped g-C_(3) N_(4)/g-C_(3) N_(4) isotype step-scheme heterojunction,which endows highly efficient photocatalytic reaction process.Therefore,the optimal sample possesses remarkable photocatalytic H_(2) evolution activity(5548.1 μmol g^(-1) h^(-1)) and robust durability.Most importantly,the investigation will open up a new path for the exploration of other carbon-based isotype S-scheme heterojunctions.展开更多
The structural,electronic,mechanical properties,and frequency-dependent refractive indexes of GaSe1-xSx（x=0,0.25,and 1） are studied by using the first-principles pseudopotential method within density functional theo...The structural,electronic,mechanical properties,and frequency-dependent refractive indexes of GaSe1-xSx（x=0,0.25,and 1） are studied by using the first-principles pseudopotential method within density functional theory.The calculated results demonstrate the relationships between intralayer structure and elastic modulus in GaSe1-xSx（x=0,0.25,and 1）.Doping of ε-GaSe with S strengthens the Ga-X bonds and increases its elastic moduli of C（11） and C（66）.Born effective charge analysis provides an explanation for the modification of cleavage properties about the doping of e-GaSe with S.The calculated results of band gaps suggest that the distance between intralayer atom and substitution of S（Se）,rather than interlayer force,is a key factor influencing the electronic exciton energy of the layer semiconductor.The calculated refractive indexes indicate that the doping of ε-GaSe with S reduces its refractive index and increases its birefringence.展开更多
Heteroatom-doped carbon dots(CDs) have attracted extensive interest because of their improved electronic and fluorescence properties with heteroatom doping. In this study, a new synthetic method for nitrogen(N) and su...Heteroatom-doped carbon dots(CDs) have attracted extensive interest because of their improved electronic and fluorescence properties with heteroatom doping. In this study, a new synthetic method for nitrogen(N) and sulfur(S)-doped CDs was developed via a hydrothermal method using methionine and citric acid as raw materials. The as-prepared CDs exhibit excellent optical properties and good biocompatibility. The spherical N,S-doped CDs have an average diameter of 5 nm. They consist of C, O, N and S, and take on excellent water solubility due to the hydroxyl and carboxyl, amino groups on the surface.The CDs have a photoluminescence quantum yield of 13.8% using quinine sulfate as a reference; the average fluorescence lifetime of the CDs was 3.67 ns. The CDs solution present good photoluminescence properties, and the maximum excitation wavelength and emission wavelength locate at 330 nm and405 nm, respectively. In addition, their fluorescence intensity almost does not change under the conditions of acid, alkali, and high salt, which indicated their anti-photobleaching property and good light stability. Based on the good biocompatibility and strong fluorescence emission of the CDs, they can be used as fluorescent imaging reagents.展开更多
The major challenge for realistic application of Li-S batteries lies in the great difficulty in breaking through the obstacles of the sluggish kinetics and polysulfides shuttle of the sulfur cathode at high sulfur loa...The major challenge for realistic application of Li-S batteries lies in the great difficulty in breaking through the obstacles of the sluggish kinetics and polysulfides shuttle of the sulfur cathode at high sulfur loading for continuously high sulfur utilization during prolonged charge-discharge cycles.Here we demonstrate that large percentage of sulfur can be effectively incorporated within a three-dimensional(3D)nanofiber network of high quality graphene from chemical vapor deposition(CVD),through a simple ball-milling process.While high quality graphene network provided continuous and durable channels to enable efficient transport of lithium ions and electrons,the in-situ sulfur doping from the alloying effect of ball milling facilitated desirable affinity with entire sulfur species to prevent sulfur loss and highly active sites to propel sulfur redox reactions over cycling.This resulted in remarkable rate-performance and excellent cycling stability,together with large areal capacity at very high sulfur mass loading(Specific capacity over 666 mAh g-1after 300 cycles at 0.5 C,and areal capacity above 5.2 mAh cm-2at 0.2C at sulfur loading of 8.0 mg cm-2 and electrolyte/sulfur(E/S)ratio of 8μL mg-1;and high reversible areal capacities of 13.1 m Ah cm-2 at a sulfur load of 15 mg cm-2 and E/S of 5μL mg-1).展开更多
基金supported by National Natural Science Foundation of China No.50730008Shanghai Science and Technology Grant No.0752nm015National Basic Research Program of China No.2006CB300406
文摘An approach was presented for synthesis of semiconducting single-walled carbon nanotubes(SWNTs) by sulfur(S) doping with the method of graphite arc discharge. Raman spectroscopy, UV-vis-NIR absorption spectroscopy and electronic properties measurements indicated the semconducting properties of the SWNTs samples. Simulant calculation indicated that S doping could induce convertion of metallic SWNTs into semiconducting ones. This strategy may pave a way for the direct synthesis of pure semiconducting SWNTs.
基金the National Key Research and Development Program of China(Nos.2017 YFA0206500 and 2018YFA0209103)the National Natural Science Foundation of China(Nos.21832003,21773111,21972061,51571110,and 21573107).The numerical calculations have been done on the computing facilities in the High Performance Computing Center(HPCC)of Nanjing University.
文摘Metal-nitrogen-carbon materials are promising catalysts for CO2 electroreduction to CO. Herein, by taking the unique hierarchical carbon nanocages as the support, an advanced nickel-nitrogen-carbon single-site catalyst is conveniently prepared by pyrolyzing the mixture of NiCl2 and phenanthroline, which exhibits a Faradaic efficiency plateau of > 87% in a wide potential window of −0.6 – −1.0 V. Further S-doping by adding KSCN into the precursor much enhances the CO specific current density by 68%, up to 37.5 A·g−1 at −0.8 V, along with an improved CO Faradaic efficiency plateau of > 90%. Such an enhancement can be ascribed to the facilitated CO pathway and suppressed hydrogen evolution from thermodynamic viewpoint as well as the increased electroactive surface area and improved charge transfer fromkinetic viewpoint due to the S-doping. This study demonstrates a simple and effective approach to advanced electrocatalysts by synergetic modification of the porous carbon-based support and electronic structure of the active sites.
基金financial supports from the Research Office of Amirkabir University of Technology (Tehran Polytechnic)
文摘Several nanoporous Fe2 O3-xSx/S-doped g-C3 N4（CNS） Z-scheme hybrid heterojuctions have been successfully synthesized by one-pot in situ growth of the Fe2O3-xSx particles on the surface of CNS. The characterization results show that S-doping in the g-C3 N4 backbone can greatly enhance the charge mobility and visible light harvesting capability. In addition, porous morphology of hybrid composite provides available open pores for vip molecules and also improves light absorbing property due to existence of multiple scattering effects. More importantly, the Fe2 O3-xSx nanoparticles formed intimate heterojunction with CNS and developed the efficient charge transfer by extending interfacial interactions occurred at the interfaces of both components. It has been found that the Fe2 O3-xSx/CNS composites have an enhanced photocatalytic activity under visible light irradiation compared with isolated Fe2 O3 and CNS components toward the photocatalytic degradation of methylene blue（MB）. The optimal loaded Fe2 O3-xSx value obtained is equal to 6.6 wt% that provided 82% MB photodegradation after 150 min with a reaction rate constant of 0.0092 min（-1） which was faster than those of the pure Fe2 O3（0.0016 min（-1））and CNS（0.0044 min（-1）） under the optimized operating variables acquired by the response surface methodology. The specific surface area and the pore volume of Fe2 O3（6.6）/CNS hybrid are 33.5 m2/g and0.195 cm3/g, which are nearly 3.8 and 7.5 times greater compared with those of the CNS, respectively. The TEM image of Fe2 O3（6.6）/CNS nanocomposite exhibits a nanoporous morphology with abundant uniform pore sizes of around 25 nm. Using the Mott-Schottky plot, the conduction and valence bands of the CNS are measured（at pH = 7） equal to-1.07 and 1.48 V versus normal hydrogen electrode（NHE）, respectively.Trapping tests prove that ·OH-and ·O2-radicals are major active species in the photocatalytic reaction.It has been established that formation of the Z-scheme Fe2 O3（6.6）/CNS heterojunction between CNS and Fe2 O3 directly produces ·OH as well as ·O2-radicals which is consistent with the results obtained from trapping experiments.
基金supported by the National Key R&D Program of China(No.2021YFB2401900).
文摘Metal selenides have been explored as promising sodium storage materials owing to their high theoretical capacity.However,sluggish Naþdiffusion and low electronic conductivity of selenides still hinder their practical applications.Herein,FeSe_(2-x)S_(x)microspheres have been prepared via a self-doping solvothermal method using NH4Fe(SO4)2 as both the Fe and S source,followed by gas phase selenization.The density functional theory calculation results reveal that S doping not only improves the Na adsorption,but also lower the diffusion energy barrier of Na atoms at the S doping sites,at the same time enhance the electronic conductivity of FeSe_(2-x)S_(x).The carbon-free nature of the FeSe_(2-x)S_(x)microspheres results in a low specific surface area and a high tap density,leading to an initial columbic efficiency of 85.6%.Compared with pure FeSe_(2),such FeSe_(2-x)S_(x)delivers a high reversible capacity of 373.6 mAh⋅g^(-1)at a high current density of 5 A⋅g^(-1)after 2000 cycles and an enhanced rate performance of 305.8 mAh⋅g^(-1)at even 50 A⋅g1.Finally,the FeSe_(2-x)S_(x)//NVP pouch cells have been assembled,achieving high energy and volumetric energy densities of 118 Wh⋅kg1 and 272 mWh⋅cm3,respectively,confirming the potential of applications for the FeSe_(2-x)S_(x)microspheres.
基金supported by the National Natural Science Foundation of China(Nos.22006131 and 22276171)the Zhejiang Provincial Natural Science Foundation of China(No.LQ20B070010)+1 种基金the China Postdoctoral Science Foundation(Nos.2020T130598 and 2019M662106)the Fund of Zhuhai Science and Technology Bureau,China(No.ZH22017003210025PWC)。
文摘Photocatalysis using the abundant solar energy is an environmentally friendly and efficient way to degrade organic matter.Covalent triazine frameworks(CTFs),a new class of metal-free organic semiconductors responsive to visible light,are promising materials for water treatment.In this study,an original CTF,namely CTF-1,was modified by S-doping to form CTFSx,which were used as metal-free catalysts for degradation of methyl orange(MO)and bisphenol A(BPA).The outcomes demonstrated that the photocatalytic degradation of MO and BPA by CTFSxwas superior to that by CTF-1,with better stability and reusability.Within 6 h,53.2%MO and 84.7%BPA were degraded by CTFS5,and the degradation rate constants were 0.145 h-1and 0.29 h-1,respectively,which were 3.6 and 5.8 times higher than those of CTF-1.Further investigation revealed that enhanced visible light absorption,a reduced degree of free carrier recombination,rapid separation and transfer of photogenerated electrons and holes,and improved·OH oxidation capacity were important factors contributing to the significantly enhanced photocatalytic activity.The S-doping method effectively improved the light absorption performance,electronic structure,and modulation band structure of CTF-1.This work highlights the potential application of low-cost metal-free catalysts driven by visible light for the removal of organic pollutants from wastewater.
基金Financial support from National Natural Science Foundation of China(Nos.51702056 and 51772135)the Ministry of Education of China(6141A02022516)China Postdoctoral Science Foundation(2017M622902 and 2019T120790).
文摘Na-ion batteries(NIBs)have attracted considerable attention in recent years owing to the high abundance and low cost of Na.It is well known that S doping can improve the electrochemical performance of carbon materials for NIBs.However,the current methods for S doping in carbons normally involve toxic precursors or rigorous conditions.In this work,we report a creative and facile strategy for preparing S-doped porous carbons(SCs)via the pyrolysis of conjugated microporous polymers(CMPs).Briefly,thiophene-based CMPs served as the precursors and doping sources simultaneously.Simple direct carbonization of CMPs produced S-doped carbon materials with highly porous structures.When used as an anode for NIBs,the SCs exhibited a high reversible capacity of 440 mAh g?1 at 50 mA g?1 after 100 cycles,superior rate capability,and excellent cycling stability(297 mAh g?1 after 1000 cycles at 500 mA g?1),outperforming most S-doped carbon materials reported thus far.The excellent performance of the SCs is attributed to the expanded lattice distance after S doping.Furthermore,we employed ex situ X-ray photoelectron spectroscopy to investigate the electrochemical reaction mechanism of the SCs during sodiation-desodiation,which can highlight the role of doped S for Na-ion storage.
基金supported financially by the Basic Science Research Program through the National Research Foundation of Korea(NRF)funded by the Ministry of Science,ICT and Future Planning(No.NRF-2017R1E1A1A01074266)the Industrial Fundamental Technology Development Program(No.10076350)funded by the Ministry of Trade,Industry and Energy(MOTIE)of Korea.
文摘In this work,a simple synthesis of sulfur doped graphitic carbon nitride(S-g-C3N4)act as a support cum stabilizers for gold nanoparticles(Au)and its was characterized by UV–vis and XRD to measure the absorbance and crystallinity,respectively.The functional group and morphology of the samples were identified using FT-IR and TEM.Finally,the Au@S-g-C3N4 nanocatalyst exhibits good catalytic performance and stability in the reduction of hazardous 4-nitrophenol(NP)compared to S-g-C3N4 using Na BH4.Moreover,the Au@S-g-C3N4 nanocomposite holds a good catalytic efficiency(near 100%)achieved by within 5 min.The highest catalytic reduction of NP is due to the synergistic effect of Au nanoparticles decorated on S-g-C3N4.The fast electron transfer reduction mechanism was elucidated and discussed.Excellent reusability and stability of the developed nanocomposites were also observed in consecutive reduction experiments.The filtering and catalyzing device was used for the direct conversion of NP polluted water.This method can open a new avenue for the metal nanoparticles based carbon materials heterogeneous catalyst and its reduction of toxic contaminants.
基金financial supports provided by the National Natural Science Foundation of China (21871164)the Taishan Scholar Project Foundation of Shandong Province (ts20190908, ts201511004)the Natural Science Foundation of Shandong Province (ZR2019MB024)。
文摘Titanium dioxide(TiO_2) has been investigated broadly as a stable,safe,and cheap anode material for sodium-ion batteries in recent years.However,the poor electronic conductivity and inherent sluggish sodium ion diffusion hinder its practical applications.Herein,a self-template and in situ vulcanization strategy is developed to synthesize self-supported hybrid nanotube arrays composed of nitrogen/sulfur-codoped carbon coated sulfur-doped TiO_2 nanotubes(S-TiO_2@NS-C) starting from H_2 Ti_2 O_5-H_2 O nanoarrays.The S-TiO_2@NS-C composite with one-dimensional nano-sized subunits integrates several merits.Specifically,sulfur doping strongly improves the Na~+ storage ability of TiO_2@C-N nanotubes by narrowing the bandgap of original TiO_2.Originating from the nanoarrays structures built from hollow nanotubes,carbon layer and sulfur doping,the sluggish Na~+ insertion/extraction kinetics is effectively improved and the volume variation of the electrode material is significantly alleviated.As a result,the S-TiO_2@NS-C nanoarrays present efficient sodium storage properties.The greatly improved sodium storage performances of S-TiO_2@NS-C nanoarrays confirm the importance of rational engineering and synthesis of hollow array architectures with higher complexity.
基金financially supported by the National Nature Science Foundation of China(Nos.51405199 and21301075)the Natural Science Foundation of Jiangsu Province(Nos.BK20140551 and BK20140562)+4 种基金the Postdoctoral Science Foundation of China(No.2014M561579)the Postdoctoral Science Foundation of Jiangsu Province(No.1401106C)the Opening Foundation of Jiangsu Province Material Tribology Key Laboratory(No.Kjsmcx201304)the Senior Intellectuals Fund of Jiangsu University(No.13JDG099)the Industry-Academy-Research Union Foundation of Jiangsu Province(No.BY2013065-05)
文摘In this study, S-doped NbSea （NbSo.aSel.8） powders were fabricated, and the corresponding Cu-based composites （Cu/NbSo.eSe1.8） were obtained by powder metallurgy technique. The phase compositions, physical, and tribological properties of Cu-based composites were investigated systematically. The results show that Cu matrix reacts with NbSo.2Sel.8 to produce Cu2Se and Cu0.38NbSo.2Se1.8 during sintering process, which influences the physical and tribological properties of Cu-based composites significantly. Specially, with NbS0.2Se1.8 content increasing, the density of Cu/ NbSo.2Se1.8 composites decreases, and the hardness increases firstly and then decreases, while the electric resistivity in- creases slightly. In addition, the incorporation of NbSo.2Se1.8 enhances the tribological properties of Cu greatly, which is attributed to the lubricating effect of Cuo,38NbSo.2Se1.8 and the reinforcement effect of Cu2Se. In particular, when the content of NbSo.2Sel.8 is 6 wt%, the Cu-based composite has the best tribological properties.
文摘The orientation construction of S-doped porous carbon fibers(SPCFs)is realized by the facile template-directed methodology using asphalt powder as carbon source.The unique fiber-like morphology without destruction can be well duplicated from the template by the developed methodology.MgSO4 fibers serve as both templates and S dopant,realizing the in-situ S doping into carbon frameworks.The effects of different reaction temperatures on the yield and S doping level of SPCFs are investigated.The S doping can not only significantly enhance the electrical conductivity,but also introduce more defects or disorders.As anode material for lithium ion batteries(LIBs),SPCFs electrode delivers better rate capability than undoped PCFs.And the capacity of SPCFs electrode retains around 90%after 300 cycles at 2 A g1,exhibiting good cycling stability.As the electrocatalysts for fuel cells,the onset potentials of SPCFs obtained at 800 and 900C are concentrated at 0.863 V,and the higher kinetic current densities at 0.4 V of them are larger than that of PCFs,demonstrating the superior electrocatalytic performance.Due to the synergistic effect of abundant pore channels and S doping,SPCFs electrode exhibits superior electrochemical performances as anode for LIBs and elecctrocatalyst for fuel cells,respectively.Additionally,the oriented conversion of asphalt powder into high-performance electrode material in this work provides a new way for the high value application of asphalt.
基金financially supported by the National Key R&D Program of China (No. 2021YFA1500402)the National Natural Science Foundation of China (NSFC, Nos. 21901246, 22105203 and 22175174)the Natural Science Foundation of Fujian Province (Nos. 2020J01116 and 2021J06033)。
文摘Alkaline hydrogen evolution reaction (HER) suffers from a sluggish kinetic,which requires the elaborate catalytic interface and micro-nanoscale architecture engineering of the electrocatalysts to accelerate the water dissociation and hydrogen evolution.Herein,the heterointerface engineering was proposed for promoting the alkaline HER by constructing the highly exposed Ru/RuS_(2) heterostructures homogeneously distributed on hollow N/S-doped carbon microspheres (Ru/RuS_(2)@h-NSC).Benefited from the synergistic effect of heterointerfacial Ru/RuS_(2),the high accessibility of the active sites on both inner and outer surface of mesoporous shells and the efficient mass transport,Ru/RuS_(2)@h-NSC affords a remarkable catalytic performance with an overpotential of 26 mV@10 mA/cm^(2) for alkaline HER,outperforming most of the state-of-the-art catalysts.Further applying Ru/RuS_(2)@h-NSC and its oxidized derivate for the overall alkaline water splitting,the required cell voltage is much lower than that of the commercial Pt/C||RuO_(2)pair to achieve the same current density.Our study may allow us to guide the design of micro-nanoreactors with optimal catalytic interfaces for promising electrocatalytic applications.
基金financially supported by the Natural Science Funds (NSF) for Distinguished Young Scholar of Heilongjiang Province (No. JC2018004)。
文摘Superior bifunctional electrocatalysts with ultra-high stability and excellent efficiency are crucial to boost the oxygen evolution reaction(OER) and the hydrogen evolution reduction(HER) in the overall water splitting(OWS) for the sustainable production of clean fuels. Herein, comprehensive density functional theory(DFT) computations were performed to explore the potential of several single transition metal(TM) atoms anchored on various S-doped black phosphorenes(TM/Snx-BP) for bifunctional OWS electrocatalysis. The results revealed that these candidates display good stability, excellent electrical conductivity, and diverse spin moments. Furthermore, the Rh/S12-BP catalyst was identified as an eligible bifunctional catalyst for OWS process due to the low overpotentials for OER(0.43 V) and HER(0.02 V), in which Rh and its adjacent P atoms were identified as the active sites. Based on the computed Gibbs free energies of OH~*, O~*, OOH~* and H~*, the corresponding volcano plots for OER and HER were established.Interestingly, the spin moments and the charge distribution of the active sites determine the catalytic trends of OER and HER. Our findings not only propose a promising bifunctional catalyst for OWS, but also widen the potential application of BP in electrocatalysis.
基金financial support from the Zhejiang Provincial Natural Science Foundation of China (Nos. LY17B050007, LY15B050006)521 Talent Project of ZSTU
文摘Graphene quantum dots （GODs） recently emerge as the new and appealing nanophotocatalyst because of their low-cost, environmental compatibility and the ability to facilitate the charge migration and prolong the charge lifetimes. In this work, a visible photocatalyst of S-doped graphene quantum dots （S-GQDs） was prepared by a facile hydrothermal synthesis using 1,3,6-trinitropyrene and Na2S as precursors. The well crystallization and monodispersity as well as the chemical environment of S-GQDs were characterized by transmission electron microscopy, atom force microscopy and X-ray photoelectron spectrum. A superior photocatalytic performance of S-GQDs was demonstrated for degradation of basic fuchsin under visible light irradiation. Furthermore, the possible photocatalytic mechanism was proposed based on the trapping experiments of active species.
基金supported by the National Natural Science Foundation of China(21307012)Educational Commission of Fujian Province(JK2013007,2014J01035,JA15138)
文摘S-doped Sb_2O_3 nanocrystals were synthesized using SbCl3 and thioacetamide（TAA） as starting materials by a hydrothermal method and the effects of TAA dosage on the composition and properties of resultant nanocrystals were determined.Their photocatalytic performance was evaluated using the degradation of methyl orange（MO） as a model reaction.The results suggest that TAA dosage can affect the preferential growth direction of Sb_2O_3,and further influences its photocatalytic activity.S doping can extend the optical absorption edge of Sb_2O_3 to the visible light religion,and thus endows its ability to photocatalyze the degradation of MO under visible light illumination.Based on these results,the correlations between the photocatalytic activity of S-doped Sb_2O_3 and the ratio between exposed facets,specific surface area and crystallographic defects were discussed.
基金financial support from the National Natural Science Foundation of China(21878192 and 51904193)the Science and Technology Cooperation Special Fund of Sichuan University and Zigong City(2022CDZG-9 and 2023CDZG-5)。
文摘Bismuth(Bi)anodes have been widely investigated for potential application in sodium-ion batteries(SIBs)due to their ultrahigh theoretical volumetric capacity(3800 mAh cm^(-3))and suitable sodiation potential(0.5-0.7 V).Unfortunately,either Bi or Bi-based compounds still face tricky challenges of unsatisfying reversible capacity(<350 mAh g^(-1))and inferior initial Coulombic efficiency(ICE,<70%).Herein,a controllable trace-sulfurization strategy is proposed to address these challenges by developing a yolkshell Bi/Bi_(2)S_(3)heterostructure encapsulated within S-doped carbon shells(TS-Bi/C).This approach strategically incorporates a trace amount of high-capacity Bi_(2)S_(3)phase with metallic Bi,consequently building regional Bi/Bi_(2)S_(3)heterointerfaces for enhancing interfacial charge transfer and sodium storage reversibility.Moreover,a thin and homogeneous solid electrolyte film(~5 nm)was formed on the surface of TS-Bi/C during the initial discharge-charge process.These merits result in an approximate 30%increase in ICE of TS-Bi/C(87.4%)compared to pure Bi/C(57,6%)when employed as anodes in SIBs,together with boosted discharge capacity of 462.3 mAh g^(-1)at 0.1 A g^(-1)and high rate capability of 382.4 mAh g^(-1)at 10 A g^(-1).Importantly,as compared to both Bi/C and Bi_(2)S_(3)/C counterparts,TS-Bi/C can deliver superior volumetric capacity as high as 1553 mAh cm^(-3)owing to its considerable tap density of 3.43 g cm^(-3).
基金support of the National Natural Science Foundation of China(Nos.52174238,22378103,52204307,and 22409128)Natural Science Foundation of Changsha(No.kq2208425)the Research Foundation Bureau of Hunan Province(No.24B0787).
文摘Heterojunctions constructed by traditional methods often result in random stacking of materials, leading to lattice mismatch, which adversely affects the extraction and transfer of photo-generated carriers and, in turn, hampers light utilization efficiency. In this work, we report a novel heterojunction comprising alternating S-doped g-C_(3)N_(4) (SCN) and N-doped MoS_(2) (NMS), bridged by Mo–N covalent bonds within hierarchical periodic macroporous (HPM) walls. This heterojunction is synthesized by co-pyrolyzing dicyandiamide, thiourea, and ammonium molybdate. Transient reflectance photoluminescence measurements reveal that the Mo–N covalent bonds serve as “fast tracks” for electron transfer from SCN to NMS, significantly enhancing the charge separation efficiency. Additionally, the well-defined spatial separation of photo-induced carriers, coupled with the efficient mass transfer within the HPM structure, promotes superior carrier utilization. Thanks to the synergistic effect of HPM structures and the bridged Mo–N bonds, the optimized HPM NMS/SCN-1.3 sample exhibits a remarkable H_(2) evolution rate of 473.3 µmol g^(−1) h^(−1) under visible light irradiation, which is approximately 163 and 19 times higher than bulk g-C_(3)N_(4) (BCN) and HPM SCN, respectively. This work offers valuable insights into the design of HPM heterojunctions composed of co-catalysts and host catalysts, paving the way for enhanced photocatalytic H₂ evolution.
基金supported by the National Natural Science Foundation of China (Nos.62004143 and 21975084)the Central Government Guided Local Science and Technology Development Special Fund Project (No.2020ZYYD033)+5 种基金the Natural Science Foundation of Hubei Province (No.2021CFB133)the Opening Fund of Key Laboratory of Rare Mineral,Ministry of Natural Resources(No.KLRM-KF 202005)the Opening Fund of Key Laboratory for Green Chemical Process of Ministry of Education of Wuhan Institute of Technology (No.GCP202101)the Open Research Fund of Key Laboratory of Material Chemistry for Energy Conversion and Storage (HUST),Ministry of Education (No.2021JYBKF05)the Innovation Project of Engineering Research Center of Phosphorus Resources Development and Utilization of Ministry of Education (No.LCX2021003)the 12^(th) Graduate Education Innovation Fund of Wuhan Institute of Technology (No.CX2020341)。
文摘The rational fabrication of an efficient heterojunction is critical to the enhancement of photocatalytic hydrogen(H_(2)) evolution performance.Herein,a new-fashioned graphitic-carbon nitride(g-C_(3) N_(4)) based isotype step-scheme(S-scheme) heterojunction composed of sulfur-doped and sulfur-free active sites is developed by liquid sulfur-mediation of exfoliated g-C_(3) N_(4).Particularly,the liquid sulfur not only contributes to the full contact between sulfur species and exfoliated g-C_(3) N_(4),but also creates sulfur-doping and abundant pores,since self-gas foaming effect of sulfur vapor.Moreover,the S-doped and S-free active sites located in the structural unit of C_(3) N_(4) jointly construct a typical sulfur-doped g-C_(3) N_(4)/g-C_(3) N_(4) isotype step-scheme heterojunction,which endows highly efficient photocatalytic reaction process.Therefore,the optimal sample possesses remarkable photocatalytic H_(2) evolution activity(5548.1 μmol g^(-1) h^(-1)) and robust durability.Most importantly,the investigation will open up a new path for the exploration of other carbon-based isotype S-scheme heterojunctions.
基金supported by the National Natural Science Foundation of China(Grant No.51202250)
文摘The structural,electronic,mechanical properties,and frequency-dependent refractive indexes of GaSe1-xSx（x=0,0.25,and 1） are studied by using the first-principles pseudopotential method within density functional theory.The calculated results demonstrate the relationships between intralayer structure and elastic modulus in GaSe1-xSx（x=0,0.25,and 1）.Doping of ε-GaSe with S strengthens the Ga-X bonds and increases its elastic moduli of C（11） and C（66）.Born effective charge analysis provides an explanation for the modification of cleavage properties about the doping of e-GaSe with S.The calculated results of band gaps suggest that the distance between intralayer atom and substitution of S（Se）,rather than interlayer force,is a key factor influencing the electronic exciton energy of the layer semiconductor.The calculated refractive indexes indicate that the doping of ε-GaSe with S reduces its refractive index and increases its birefringence.
基金financially supported by the National Natural Science Foundation of China (NSFC, No. 21535006 and No. 21705132)the Fundamental Research Funds for the Central Universities (XDJK2017C065)
文摘Heteroatom-doped carbon dots(CDs) have attracted extensive interest because of their improved electronic and fluorescence properties with heteroatom doping. In this study, a new synthetic method for nitrogen(N) and sulfur(S)-doped CDs was developed via a hydrothermal method using methionine and citric acid as raw materials. The as-prepared CDs exhibit excellent optical properties and good biocompatibility. The spherical N,S-doped CDs have an average diameter of 5 nm. They consist of C, O, N and S, and take on excellent water solubility due to the hydroxyl and carboxyl, amino groups on the surface.The CDs have a photoluminescence quantum yield of 13.8% using quinine sulfate as a reference; the average fluorescence lifetime of the CDs was 3.67 ns. The CDs solution present good photoluminescence properties, and the maximum excitation wavelength and emission wavelength locate at 330 nm and405 nm, respectively. In addition, their fluorescence intensity almost does not change under the conditions of acid, alkali, and high salt, which indicated their anti-photobleaching property and good light stability. Based on the good biocompatibility and strong fluorescence emission of the CDs, they can be used as fluorescent imaging reagents.
基金supported by the National Natural Science Foundation of China (Nos.51972287, 51502269)Natural Science Foundation of Henan Province (No.182300410187)Outstanding Young Talent Research Fund of Zhengzhou University (No.1521320023)。
文摘The major challenge for realistic application of Li-S batteries lies in the great difficulty in breaking through the obstacles of the sluggish kinetics and polysulfides shuttle of the sulfur cathode at high sulfur loading for continuously high sulfur utilization during prolonged charge-discharge cycles.Here we demonstrate that large percentage of sulfur can be effectively incorporated within a three-dimensional(3D)nanofiber network of high quality graphene from chemical vapor deposition(CVD),through a simple ball-milling process.While high quality graphene network provided continuous and durable channels to enable efficient transport of lithium ions and electrons,the in-situ sulfur doping from the alloying effect of ball milling facilitated desirable affinity with entire sulfur species to prevent sulfur loss and highly active sites to propel sulfur redox reactions over cycling.This resulted in remarkable rate-performance and excellent cycling stability,together with large areal capacity at very high sulfur mass loading(Specific capacity over 666 mAh g-1after 300 cycles at 0.5 C,and areal capacity above 5.2 mAh cm-2at 0.2C at sulfur loading of 8.0 mg cm-2 and electrolyte/sulfur(E/S)ratio of 8μL mg-1;and high reversible areal capacities of 13.1 m Ah cm-2 at a sulfur load of 15 mg cm-2 and E/S of 5μL mg-1).
