Mn-rich LiFe_(1-x)Mn_(x)PO_(4)(x>0.5),which combines the high operation voltage of LiMnPO_(4)with excellent rate performa nce of LiFePO4,is hindered by its sluggish kinetic properties.Herein,thermodynamic equilibri...Mn-rich LiFe_(1-x)Mn_(x)PO_(4)(x>0.5),which combines the high operation voltage of LiMnPO_(4)with excellent rate performa nce of LiFePO4,is hindered by its sluggish kinetic properties.Herein,thermodynamic equilibrium analysis of Mn^(2+)-Fe^(2+)-Mg^(2+)-C_(2)O_(4)^(2-)-H_(2)O system is used to guide the design and preparation of insitu Mg-doped(Fe_(0.4)Mn_(0.6))_(1-x)Mg_(x)C_(2)O_(4)intermediate,which is then employed as an innovative precursor to synthesize high-performance Mg-doped LiFe_(0.4)Mn_(0.6)PO_(4).It indicates that the metal ions with a high precipitation efficiency and the stoichiometric precursors with uniform element distribution can be achieved under the optimized thermodynamic conditions.Meanwhile,accelerated Li+diffusivity and reduced charge transfer resistance originating from Mg doping are verified by various kinetic characterizations.Benefiting from the contributions of inherited homogeneous element distribution,small particle size,uniform carbon layer coating,enhanced Li+migration ability and structural stability induced by Mg doping,the Li(Fe_(0.4)Mn_(0.6))_(0.97)Mg_(0.03)PO_(4)/C exhibits splendid electrochemical performance.展开更多
The preparation of materials with enhanced magnetocaloric properties is crucial for magnetic refrigeration. In thisstudy, Nd-doped Gd5Si4 microparticles and nanomaterials were synthesized using the reduction–diffusio...The preparation of materials with enhanced magnetocaloric properties is crucial for magnetic refrigeration. In thisstudy, Nd-doped Gd5Si4 microparticles and nanomaterials were synthesized using the reduction–diffusion method. Theimpact of Nd doping with varying compositions on the structure and entropy change properties of the materials was investigated.The Curie temperatures of both the micron- and nano-sized materials ranged from 190 K to 210 K, which were lowerthan previously reported values. Micron-sized samples doped with 1% Nd exhibited superior magnetocaloric properties,demonstrating a maximum entropy change of 4.98 J·kg^(-1)·K^(-1) at 5 T, with an entropy change exceeding 4 J·kg^(-1)·K^(-1)over a wide temperature range of approximately 70 K. Conversely, the nanomaterials had broader entropy change peaks butlower values. All samples exhibited a second-order phase transition, as confirmed by the Arrott plots.展开更多
A series of nitrogen-doped SrMoO_(4) with different Sr/N mole ratio (R=0,0.05,0.10,0.15,0.20,0.40,and 0.60) were synthesized using urea as the N source via the vapor-thermal method.The photocatalytic degradation abili...A series of nitrogen-doped SrMoO_(4) with different Sr/N mole ratio (R=0,0.05,0.10,0.15,0.20,0.40,and 0.60) were synthesized using urea as the N source via the vapor-thermal method.The photocatalytic degradation ability of all samples was evaluated using methylene blue (MB) as a target contaminant.The band gaps of N-doped samples are all higher than that of pristine ones,which is only 3.12 eV.BET specific surface area S_(BET) and pore volume are increased due to the N doping.And the greater increase of S_(BET),the faster the photodegradation speed of methylene blue on SrMoO_(4).More specifically,the degradation efficiency of MB is improved up to 87%in 100 min.展开更多
Aluminum doped zinc oxide （AZO）, as an electrically conductive material, was applied to coating on the surface of olivine-type LiFePO4 synthesized by solid-state method. The charge-discharge test results show that t...Aluminum doped zinc oxide （AZO）, as an electrically conductive material, was applied to coating on the surface of olivine-type LiFePO4 synthesized by solid-state method. The charge-discharge test results show that the rate performance and low-temperature performance of LiFePO4 are greatly improved by the surface treatment. Even at 20C rate, the discharge specific capacity of 100.9 mA.h/g was obtained by the AZO-coated LiFePO4 at room temperature. At -20 ℃, the discharge specific capacity at 0.2C for un-coated LiFePO4 and the coated one are 50.3 mA.h/g and 119.4 mA.h/g, respectively. It should be attributed to the electrically conductive AZO-coating which increases the electronic conductivity of LiFePO4. Furthermore, the surface-coating increases the tap-density of LiFePO4. The results indicate that the AZO-coated LiFePO4 is a good candidate of cathode material for applying in lithium power batteries.展开更多
Fe-doped BiVO4with hierarchical flower-like structure was prepared via a hydrothermal method using sodium dodecylbenzene sulfonate(SDBS)as structure directing agent.X-ray diffraction(XRD),scanning electron microscope(...Fe-doped BiVO4with hierarchical flower-like structure was prepared via a hydrothermal method using sodium dodecylbenzene sulfonate(SDBS)as structure directing agent.X-ray diffraction(XRD),scanning electron microscope(SEM),transmissionelectron microscope(TEM),high resolution transmission electron microscope(HRTEM),X-ray photoelectron spectroscopy(XPS)and UV-Vis were applied for characterization of the as-prepared samples.The formation mechanism of flower-like structure wasproposed based on the evolution of morphology as a function of hydrothermal time.Fe-doped into substitutional sites of BiVO4effectively improved the migration and separation of photogenerated carrier and enhanced the utilization of visible light.Flower-likeFe-doped BiVO4showed much higher visible-light-driven photocatalytic efficiency for degradation of methyl blue compared withthe pristine BiVO4.And the sample with a Fe/Bi mole ratio of2.5%showed the highest photocatalytic efficiency.展开更多
Photocatalytic hydrogen production based on semiconductor photocatalysts has been considered as one of the most promising strategies to resolve the global energy shortage.Graphitic carbon nitride(g‐C3N4)has been a st...Photocatalytic hydrogen production based on semiconductor photocatalysts has been considered as one of the most promising strategies to resolve the global energy shortage.Graphitic carbon nitride(g‐C3N4)has been a star visible‐light photocatalyst in this field due to its various advantages.However,pristine g‐C3N4usually exhibits limited activity.Herein,to enhance the performance of g‐C3N4,alkali metal ion(Li+,Na+,or K+)‐doped g‐C3N4are prepared via facile high‐temperature treatment.The prepared samples are characterized and analyzed using the technique of XRD,ICP‐AES,SEM,UV‐vis DRS,BET,XPS,PL,TRPL,photoelectrochemical measurements,photocatalytic tests,etc.The resultant doped photocatalysts show enhanced visible‐light photocatalytic activities for hydrogen production,benefiting from the increased specific surface areas(which provide more active sites),decreased band gaps for extended visible‐light absorption,and improved electronic structures for efficient charge transfer.In particular,because of the optimal tuning of both microstructure and electronic structure,the Na‐doped g‐C3N4shows the most effective utilization of photogenerated electrons during the water reduction process.As a result,the highest photocatalytic performance is achieved over the Na‐doped g‐C3N4photocatalyst(18.7?mol/h),3.7times that of pristine g‐C3N4(5.0?mol/h).This work gives a systematic study for the understanding of doping effect of alkali metals in semiconductor photocatalysis.展开更多
The exploration of active and long-lived oxygen reduction reaction(ORR)catalysts for the commercialization of zinc-air batteries are of immense significance but challenging.Herein,the sulfur doped FeWO_(4)embedded in ...The exploration of active and long-lived oxygen reduction reaction(ORR)catalysts for the commercialization of zinc-air batteries are of immense significance but challenging.Herein,the sulfur doped FeWO_(4)embedded in the multi-dimensional nitrogen-doped carbon structure(S-FeWO_(4)/NC)was successfully synthesized.The doped S atoms optimized the charge distribution in FeWO_(4)and enhanced the intrinsic activity.At the same time,S doping accelerated the formation of reaction intermediates during the adsorption reduction of O_(2)on the surface of S-FeWO_(4)/NC.Accordingly,the S-FeWO_(4)/NC catalyst showed more positive half-wave potential(0.85 V)and better stability than that of the FeWO_(4)/NC catalyst.Furthermore,the S-FeWO_(4)/NC-based zinc-air battery exhibited considerable power density of 150.3m W cm^(-2),high specific capacity of 912.7 m A h g^(-1),and prominent cycle stability up to 220 h.This work provides an assistance to the development of cheap and efficient tungsten-based oxygen reduction catalysts and the promotion of its application in the zinc-air battery.展开更多
Multifunctional non-precious catalysts for hydrogen/oxygen evolution reaction(HER/OER) and oxygen reduction reaction(ORR) constitute the bottleneck in the applications in electrochemical overall water splitting(OWS) a...Multifunctional non-precious catalysts for hydrogen/oxygen evolution reaction(HER/OER) and oxygen reduction reaction(ORR) constitute the bottleneck in the applications in electrochemical overall water splitting(OWS) and Zn-air batteries. Herein, a trifunctional electrocatalyst of urchin-like Al,P-codoped Co3O4 microspheres supported on Ni foam(denoted as AP-CONPs/NF) was fabricated via a hydrothermal process and subsequent low-temperature annealing and phosphorization, exhibiting enhanced OER, HER and ORR activities compared with single-doped and undoped samples. Their surface self-organized microstructure and excellent "superaerophobic" feature make a high bubble repellency, which boost diffusion of reactants and electrolyte-electrode intimate contact. The codoping of Al and P elements into Co3O4 betters right the balance among surface chemical state, the increased oxygen vacancies and the promoted charge transfer. Encouraged by these synergistic advantages, the AP-CONPs/NF was further employed as excellent bifunctional electrodes for the OWS(low cell voltage of 1.57 V at 10 mA cm-2) and as air cathode for rechargeable Zn-air batteries(high power density of 89.1 mW cm-2), which demonstrates a great feasibility for practical applications.展开更多
Ce^(3+)/Tb^(3+) co-doped and Ce^(3+)/Tb^(3+)/Eu^(3+) tri-doped β-NaYF_(4) photoluminescent microcrystals using oleic acid as surfactant were synthesized using the solvothermal method.Their microstructural characteris...Ce^(3+)/Tb^(3+) co-doped and Ce^(3+)/Tb^(3+)/Eu^(3+) tri-doped β-NaYF_(4) photoluminescent microcrystals using oleic acid as surfactant were synthesized using the solvothermal method.Their microstructural characteristics and photoluminescence properties were investigated in detail.They have the shape of hexagonal prism bipyramids with uniform particle size,which decreases with the concentrations of Tb^(3+) and Eu^(3+).The energy transfer processes of both the Ce^(3+)→Tb^(3+) and the Ce^(3+)→Tb^(3+)→Eu^(3+) were systematically studied.Compared with Eu^(3+) or Tb^(3+) single-doped β-NaYF_(4) microcrystals,the sensitization by Ce^(3+) for the photoluminescence of Tb^(3+) and Eu^(3+) leads to a broad excitation spectral bandwidth in the ultraviolet (UV) range.Meanwhile,the corresponding optical absorption efficiency is greatly enhanced.High energy transfer efficiencies have been observed from Ce^(3+) to Tb^(3+) and from Tb^(3+) to Eu^(3+).展开更多
The activation of H_(2)O is a key step of the COS hydrolysis,which may be tuned by oxygen vacancy defects in the catalysts.Herein,we have introduced Cu into Co_(3)O_(4) to regulate the oxygen vacancy defect content of...The activation of H_(2)O is a key step of the COS hydrolysis,which may be tuned by oxygen vacancy defects in the catalysts.Herein,we have introduced Cu into Co_(3)O_(4) to regulate the oxygen vacancy defect content of the catalysts.In situ DRIFTS and XPS spectra reveal that COS and H_(2)O are adsorbed and activated by oxygen vacancy.The 10 at%Cu doped Co_(3)O_(4) sample(10Cu-Co_(3)O_(4))exhibits the optimal activity,100%of COS conversion at 70℃.The improved oxygen vacancies of CueCo_(3)O_(4) accelerate the activation of H_(2)O to form active -OH.COS binds with hydroxyl to form the intermediate HSCO^(-)_(2),and then the activated-OH on the oxygen vacancy reacts with HSCO^(-)_(2) to form HCO^(-)_(3).Meanwhile,the catalyst exhibits high catalytic stability because copper species(Cu+/Cu^(2+))redox cycle mitigate the sulfation of Co_(3)O_(4)(Co^(2+)/Co^(3+)).Our work offers a promising approach for the rational design of cobalt-related catalysts in the highly efficient hydrolysis COS process.展开更多
Ca1-xRxCu3Ti4O12(R=La,Y,Gd;x=0,0.1,0.2,0.3) electronic ceramics were fabricated by conventional solid-state reaction method.The microstructure and dielectric properties as well as impedance behavior were carefully inv...Ca1-xRxCu3Ti4O12(R=La,Y,Gd;x=0,0.1,0.2,0.3) electronic ceramics were fabricated by conventional solid-state reaction method.The microstructure and dielectric properties as well as impedance behavior were carefully investigated.XRD results showed that the secondary phases with the general formula R2Ti2O7 existed at grain boundaries of rare earth doped ceramics,which inhibited abnormal grain growth.The dielectric constant decreased from 4×105 in pure CaCu3Ti4O12(CCTO) ceramics to 2×103 with rare earth doping....展开更多
A ratiometric fluorescent probe for hypoxanthine(Hx)detection was established based on the mimic enzyme and fluorescence characteristics of cobalt-doped graphite-phase carbon nitride(Co doped g-C_(3)N_(4)).In addition...A ratiometric fluorescent probe for hypoxanthine(Hx)detection was established based on the mimic enzyme and fluorescence characteristics of cobalt-doped graphite-phase carbon nitride(Co doped g-C_(3)N_(4)).In addition to emitting strong fluorescence,the peroxidase activity of Co doped g-C_(3)N_(4)can catalyze the reaction of O-phenylenediamine and H_(2)O_(2)to produce diallyl phthalate which can emit yellow fluorescence at 570 nm.Through the decomposition of Hx by xanthine oxidase,Hx can be indirectly detected by the generating hydrogen peroxide based on the measurement of fluorescent ratio I(F_(570)/F_(370)).The linear range was 1.7-272.2 mg/kg(R^(2)=0.997),and the detection limit was 1.52 mg/kg(3σ/K,n=9).The established method was applied to Hx detection in bass,grass carp,and shrimp,and the data were verified by HPLC.The result shows that the established probe is sensitive,accurate,and reliable,and can be used for Hx detection in aquatic products.展开更多
To demonstrate flexible and tandem device applications,a low-temperature Cu_(2)ZnSnSe_(4)(CZTSe)deposition process,combined with efficient alkali doping,was developed.First,high-quality CZTSe films were grown at 480℃...To demonstrate flexible and tandem device applications,a low-temperature Cu_(2)ZnSnSe_(4)(CZTSe)deposition process,combined with efficient alkali doping,was developed.First,high-quality CZTSe films were grown at 480℃by a single co-evaporation,which is applicable to polyimide(PI)substrate.Because of the alkali-free substrate,Na and K alkali doping were systematically studied and optimized to precisely control the alkali distribution in CZTSe.The bulk defect density was significantly reduced by suppression of deep acceptor states after the(NaF+KF)PDTs.Through the low-temperature deposition with(NaF+KF)PDTs,the CZTSe device on glass yields the best efficiency of 8.1%with an improved Voc deficit of 646 mV.The developed deposition technologies have been applied to PI.For the first time,we report the highest efficiency of 6.92%for flexible CZTSe solar cells on PI.Additionally,CZTSe devices were utilized as bottom cells to fabricate four-terminal CZTSe/perovskite tandem cells because of a low bandgap of CZTSe(~1.0 eV)so that the tandem cell yielded an efficiency of 20%.The obtained results show that CZTSe solar cells prepared by a low-temperature process with in-situ alkali doping can be utilized for flexible thin-film solar cells as well as tandem device applications.展开更多
Integrating selective organic synthesis with hydrogen(H_(2))evolution in one photocatalytic redox reaction system sheds light on the underlying approach for concurrent employment of photogenerated electrons and holes ...Integrating selective organic synthesis with hydrogen(H_(2))evolution in one photocatalytic redox reaction system sheds light on the underlying approach for concurrent employment of photogenerated electrons and holes towards efficient production of solar fuels and chemicals.In this work,a facile one‐pot oil bath method has been proposed to fabricate a noble metal‐free ultrathin Ni‐doped ZnIn_(2)S_(4)(ZIS/Ni)composite nanosheet for effective solar‐driven selective dehydrocoupling of benzyl alcohol into value‐added C–C coupled hydrobenzoin and H_(2) fuel,which exhibits higher performance than pure ZIS nanosheet.The remarkably improved photoredox activity of ZIS/Ni is mainly attributed to the optimized electron structure featuring narrower band gap and suitable energy band position,which facilitates the ability of light harvesting and photoexcited charge carrier separation and transfer.Furthermore,it has been demonstrated that it is feasible to employ ZIS/Ni for various aromatic alcohols dehydrocoupling to the corresponding C–C coupled products.It is expected that this work can stimulate further interest on the establishment of innovative photocatalytic redox platform coupling clean solar fuels synthesis and selective organic conversion in a sustainable manner.展开更多
The electronic structures and optical properties of β-Ga_2O_3 and Si-and Sn-doped β-Ga_2O_3 are studied using the GGA + U method based on density functional theory. The calculated bandgap and Ga 3d-state peak of β-...The electronic structures and optical properties of β-Ga_2O_3 and Si-and Sn-doped β-Ga_2O_3 are studied using the GGA + U method based on density functional theory. The calculated bandgap and Ga 3d-state peak of β-Ga_2O_3 are in good agreement with experimental results. Si-and Sn-doped β-Ga_2O_3 tend to form under O-poor conditions, and the formation energy of Si-doped β-Ga_2O_3 is larger than that of Sn-doped β-Ga_2O_3 because of the large bond length variation between Ga–O and Si–O. Si-and Sn-doped β-Ga_2O_3 have wider optical gaps than β-Ga_2O_3, due to the Burstein–Moss effect and the bandgap renormalization effect. Si-doped β-Ga_2O_3 shows better electron conductivity and a higher optical absorption edge than Sn-doped β-Ga_2O_3, so Si is more suitable as a dopant of n-type β-Ga_2O_3, which can be applied in deep-UV photoelectric devices.展开更多
Nd^(3+)-doped NaGdF_(4):Yb,Tm nanocrystals were synthesized by an improved high-temperature thermal decomposition method,and the effects of doping concentrations on the crystal structure,phase composition,and upconver...Nd^(3+)-doped NaGdF_(4):Yb,Tm nanocrystals were synthesized by an improved high-temperature thermal decomposition method,and the effects of doping concentrations on the crystal structure,phase composition,and upconverted fluorescence intensity were also investigated.The results reveal that the introduction of Nd^(3+) ions does not cause the transformation of the crystal phase,but induce the change of the unit cell parameters.Meanwhile,the fluorescence intensity of the synthesized nanocrystals when co-doped with 3 mol%Nd^(3+) is the strongest under the excitation of 980 nm laser,which is 3.9 times that of the Nd^(3+)-free doped nanoparticles,and the average size is 62.9 nm.And it is located in the blue area of the CIE coordinate diagram,and the corresponding color purity is 91.81%under the same experimental conditions.The resulting nanocrystals show the potential as excellent fluorescence labeling and in vivo imaging probes.展开更多
基金financially supported by the National Natural Science Foundation of China(No.51904250)the China Postdoctoral Science Foundation(No.2021M692254)+2 种基金the Sichuan Science and Technology Program(No.2022YFG0098)the Fundamental Research Funds for the Central Universities(Nos.2021CDSN-02,2022SCU12002,2022CDZG-17,2022CDSN-08,2022CDZG-9)the Hohhot Science and Technology Program(No.2023-Jie Bang Gua Shuai-Gao-3)。
文摘Mn-rich LiFe_(1-x)Mn_(x)PO_(4)(x>0.5),which combines the high operation voltage of LiMnPO_(4)with excellent rate performa nce of LiFePO4,is hindered by its sluggish kinetic properties.Herein,thermodynamic equilibrium analysis of Mn^(2+)-Fe^(2+)-Mg^(2+)-C_(2)O_(4)^(2-)-H_(2)O system is used to guide the design and preparation of insitu Mg-doped(Fe_(0.4)Mn_(0.6))_(1-x)Mg_(x)C_(2)O_(4)intermediate,which is then employed as an innovative precursor to synthesize high-performance Mg-doped LiFe_(0.4)Mn_(0.6)PO_(4).It indicates that the metal ions with a high precipitation efficiency and the stoichiometric precursors with uniform element distribution can be achieved under the optimized thermodynamic conditions.Meanwhile,accelerated Li+diffusivity and reduced charge transfer resistance originating from Mg doping are verified by various kinetic characterizations.Benefiting from the contributions of inherited homogeneous element distribution,small particle size,uniform carbon layer coating,enhanced Li+migration ability and structural stability induced by Mg doping,the Li(Fe_(0.4)Mn_(0.6))_(0.97)Mg_(0.03)PO_(4)/C exhibits splendid electrochemical performance.
基金Project supported by the Natural Science Foundation of Gansu Province(Grant No.22JR5RA404).
文摘The preparation of materials with enhanced magnetocaloric properties is crucial for magnetic refrigeration. In thisstudy, Nd-doped Gd5Si4 microparticles and nanomaterials were synthesized using the reduction–diffusion method. Theimpact of Nd doping with varying compositions on the structure and entropy change properties of the materials was investigated.The Curie temperatures of both the micron- and nano-sized materials ranged from 190 K to 210 K, which were lowerthan previously reported values. Micron-sized samples doped with 1% Nd exhibited superior magnetocaloric properties,demonstrating a maximum entropy change of 4.98 J·kg^(-1)·K^(-1) at 5 T, with an entropy change exceeding 4 J·kg^(-1)·K^(-1)over a wide temperature range of approximately 70 K. Conversely, the nanomaterials had broader entropy change peaks butlower values. All samples exhibited a second-order phase transition, as confirmed by the Arrott plots.
基金Funded by National Key Research and Development Program of China (No.2021YFA1600203)。
文摘A series of nitrogen-doped SrMoO_(4) with different Sr/N mole ratio (R=0,0.05,0.10,0.15,0.20,0.40,and 0.60) were synthesized using urea as the N source via the vapor-thermal method.The photocatalytic degradation ability of all samples was evaluated using methylene blue (MB) as a target contaminant.The band gaps of N-doped samples are all higher than that of pristine ones,which is only 3.12 eV.BET specific surface area S_(BET) and pore volume are increased due to the N doping.And the greater increase of S_(BET),the faster the photodegradation speed of methylene blue on SrMoO_(4).More specifically,the degradation efficiency of MB is improved up to 87%in 100 min.
文摘Aluminum doped zinc oxide （AZO）, as an electrically conductive material, was applied to coating on the surface of olivine-type LiFePO4 synthesized by solid-state method. The charge-discharge test results show that the rate performance and low-temperature performance of LiFePO4 are greatly improved by the surface treatment. Even at 20C rate, the discharge specific capacity of 100.9 mA.h/g was obtained by the AZO-coated LiFePO4 at room temperature. At -20 ℃, the discharge specific capacity at 0.2C for un-coated LiFePO4 and the coated one are 50.3 mA.h/g and 119.4 mA.h/g, respectively. It should be attributed to the electrically conductive AZO-coating which increases the electronic conductivity of LiFePO4. Furthermore, the surface-coating increases the tap-density of LiFePO4. The results indicate that the AZO-coated LiFePO4 is a good candidate of cathode material for applying in lithium power batteries.
基金Project(51102025)supported by the National Natural Science Foundation of ChinaProject(14JJ7040)supported by Natural Science Foundation of Hunan Province,ChinaProject(2014GH561172)supported by China Torch Program
文摘Fe-doped BiVO4with hierarchical flower-like structure was prepared via a hydrothermal method using sodium dodecylbenzene sulfonate(SDBS)as structure directing agent.X-ray diffraction(XRD),scanning electron microscope(SEM),transmissionelectron microscope(TEM),high resolution transmission electron microscope(HRTEM),X-ray photoelectron spectroscopy(XPS)and UV-Vis were applied for characterization of the as-prepared samples.The formation mechanism of flower-like structure wasproposed based on the evolution of morphology as a function of hydrothermal time.Fe-doped into substitutional sites of BiVO4effectively improved the migration and separation of photogenerated carrier and enhanced the utilization of visible light.Flower-likeFe-doped BiVO4showed much higher visible-light-driven photocatalytic efficiency for degradation of methyl blue compared withthe pristine BiVO4.And the sample with a Fe/Bi mole ratio of2.5%showed the highest photocatalytic efficiency.
基金supported by the National Natural Science Foundation of of China(51472191,21407115,21773179)the Natural Science Foundation of Hubei Province of China(2017CFA031)the Opening Project of Key Laboratory of Optoelectronic Chemical Materials and Devices,Ministry of Education(JDGD-201509)~~
文摘Photocatalytic hydrogen production based on semiconductor photocatalysts has been considered as one of the most promising strategies to resolve the global energy shortage.Graphitic carbon nitride(g‐C3N4)has been a star visible‐light photocatalyst in this field due to its various advantages.However,pristine g‐C3N4usually exhibits limited activity.Herein,to enhance the performance of g‐C3N4,alkali metal ion(Li+,Na+,or K+)‐doped g‐C3N4are prepared via facile high‐temperature treatment.The prepared samples are characterized and analyzed using the technique of XRD,ICP‐AES,SEM,UV‐vis DRS,BET,XPS,PL,TRPL,photoelectrochemical measurements,photocatalytic tests,etc.The resultant doped photocatalysts show enhanced visible‐light photocatalytic activities for hydrogen production,benefiting from the increased specific surface areas(which provide more active sites),decreased band gaps for extended visible‐light absorption,and improved electronic structures for efficient charge transfer.In particular,because of the optimal tuning of both microstructure and electronic structure,the Na‐doped g‐C3N4shows the most effective utilization of photogenerated electrons during the water reduction process.As a result,the highest photocatalytic performance is achieved over the Na‐doped g‐C3N4photocatalyst(18.7?mol/h),3.7times that of pristine g‐C3N4(5.0?mol/h).This work gives a systematic study for the understanding of doping effect of alkali metals in semiconductor photocatalysis.
基金the support of the National Natural Science Foundation of China(Nos.22178148,U21A20328)the Natural Science Foundation of Jiangsu Province(No.BK20191430)+2 种基金the Six Talent Peaks Project in Jiangsu Province(No.XNY-009)the Jiangsu Province and Education Ministry CoSponsored Synergistic Innovation Center of Modern Agricultural Equipment(No.XTCX2029)a Project Funded by the Priority Academic Program Development of Jiangsu Higher Education Institutions。
文摘The exploration of active and long-lived oxygen reduction reaction(ORR)catalysts for the commercialization of zinc-air batteries are of immense significance but challenging.Herein,the sulfur doped FeWO_(4)embedded in the multi-dimensional nitrogen-doped carbon structure(S-FeWO_(4)/NC)was successfully synthesized.The doped S atoms optimized the charge distribution in FeWO_(4)and enhanced the intrinsic activity.At the same time,S doping accelerated the formation of reaction intermediates during the adsorption reduction of O_(2)on the surface of S-FeWO_(4)/NC.Accordingly,the S-FeWO_(4)/NC catalyst showed more positive half-wave potential(0.85 V)and better stability than that of the FeWO_(4)/NC catalyst.Furthermore,the S-FeWO_(4)/NC-based zinc-air battery exhibited considerable power density of 150.3m W cm^(-2),high specific capacity of 912.7 m A h g^(-1),and prominent cycle stability up to 220 h.This work provides an assistance to the development of cheap and efficient tungsten-based oxygen reduction catalysts and the promotion of its application in the zinc-air battery.
基金the National Natural Science Foundation of China(21421001,21573115,21875118)the Natural Science Foundation of Tianjin(17JCYBJC17100,19JCZDJC37700)。
文摘Multifunctional non-precious catalysts for hydrogen/oxygen evolution reaction(HER/OER) and oxygen reduction reaction(ORR) constitute the bottleneck in the applications in electrochemical overall water splitting(OWS) and Zn-air batteries. Herein, a trifunctional electrocatalyst of urchin-like Al,P-codoped Co3O4 microspheres supported on Ni foam(denoted as AP-CONPs/NF) was fabricated via a hydrothermal process and subsequent low-temperature annealing and phosphorization, exhibiting enhanced OER, HER and ORR activities compared with single-doped and undoped samples. Their surface self-organized microstructure and excellent "superaerophobic" feature make a high bubble repellency, which boost diffusion of reactants and electrolyte-electrode intimate contact. The codoping of Al and P elements into Co3O4 betters right the balance among surface chemical state, the increased oxygen vacancies and the promoted charge transfer. Encouraged by these synergistic advantages, the AP-CONPs/NF was further employed as excellent bifunctional electrodes for the OWS(low cell voltage of 1.57 V at 10 mA cm-2) and as air cathode for rechargeable Zn-air batteries(high power density of 89.1 mW cm-2), which demonstrates a great feasibility for practical applications.
基金Funded by the National Natural Science Foundation of China(Nos.21571095,51362020)the Jiangxi Provincial Department of Education(No.KJLD13008)the Scientific Research Projects of Hunan Education Department(No.18C1442)。
文摘Ce^(3+)/Tb^(3+) co-doped and Ce^(3+)/Tb^(3+)/Eu^(3+) tri-doped β-NaYF_(4) photoluminescent microcrystals using oleic acid as surfactant were synthesized using the solvothermal method.Their microstructural characteristics and photoluminescence properties were investigated in detail.They have the shape of hexagonal prism bipyramids with uniform particle size,which decreases with the concentrations of Tb^(3+) and Eu^(3+).The energy transfer processes of both the Ce^(3+)→Tb^(3+) and the Ce^(3+)→Tb^(3+)→Eu^(3+) were systematically studied.Compared with Eu^(3+) or Tb^(3+) single-doped β-NaYF_(4) microcrystals,the sensitization by Ce^(3+) for the photoluminescence of Tb^(3+) and Eu^(3+) leads to a broad excitation spectral bandwidth in the ultraviolet (UV) range.Meanwhile,the corresponding optical absorption efficiency is greatly enhanced.High energy transfer efficiencies have been observed from Ce^(3+) to Tb^(3+) and from Tb^(3+) to Eu^(3+).
基金the National Natural Science Foundation of China (92034301,22078063 and 22022804)Major Program of Qingyuan Innovation Laboratory (00121003)the Natural Science Foundation of Fujian Province (2020H6007)。
文摘The activation of H_(2)O is a key step of the COS hydrolysis,which may be tuned by oxygen vacancy defects in the catalysts.Herein,we have introduced Cu into Co_(3)O_(4) to regulate the oxygen vacancy defect content of the catalysts.In situ DRIFTS and XPS spectra reveal that COS and H_(2)O are adsorbed and activated by oxygen vacancy.The 10 at%Cu doped Co_(3)O_(4) sample(10Cu-Co_(3)O_(4))exhibits the optimal activity,100%of COS conversion at 70℃.The improved oxygen vacancies of CueCo_(3)O_(4) accelerate the activation of H_(2)O to form active -OH.COS binds with hydroxyl to form the intermediate HSCO^(-)_(2),and then the activated-OH on the oxygen vacancy reacts with HSCO^(-)_(2) to form HCO^(-)_(3).Meanwhile,the catalyst exhibits high catalytic stability because copper species(Cu+/Cu^(2+))redox cycle mitigate the sulfation of Co_(3)O_(4)(Co^(2+)/Co^(3+)).Our work offers a promising approach for the rational design of cobalt-related catalysts in the highly efficient hydrolysis COS process.
基金supported by the National Basic Research Program of China (973) (2007CB31407)Foundation for Innovative Research Groups of the NSFC (60721001)+1 种基金the Young Fund of Sichuan Province (08ZQ026-013)the National Natural Science Foundation of China (50972023, 50872078)
文摘Ca1-xRxCu3Ti4O12(R=La,Y,Gd;x=0,0.1,0.2,0.3) electronic ceramics were fabricated by conventional solid-state reaction method.The microstructure and dielectric properties as well as impedance behavior were carefully investigated.XRD results showed that the secondary phases with the general formula R2Ti2O7 existed at grain boundaries of rare earth doped ceramics,which inhibited abnormal grain growth.The dielectric constant decreased from 4×105 in pure CaCu3Ti4O12(CCTO) ceramics to 2×103 with rare earth doping....
基金supported by the National Natural Science Foundation of China(21804050)the National Key R and D Program of China(2018YFD0901003)+2 种基金the Science and Technology Planning Project of Xiamen,China(3502Z20183031)the Fujian Provincial Fund Project(2018J01432)the Xiamen Science and Technology Planning Project,China(3502Z20183031)。
文摘A ratiometric fluorescent probe for hypoxanthine(Hx)detection was established based on the mimic enzyme and fluorescence characteristics of cobalt-doped graphite-phase carbon nitride(Co doped g-C_(3)N_(4)).In addition to emitting strong fluorescence,the peroxidase activity of Co doped g-C_(3)N_(4)can catalyze the reaction of O-phenylenediamine and H_(2)O_(2)to produce diallyl phthalate which can emit yellow fluorescence at 570 nm.Through the decomposition of Hx by xanthine oxidase,Hx can be indirectly detected by the generating hydrogen peroxide based on the measurement of fluorescent ratio I(F_(570)/F_(370)).The linear range was 1.7-272.2 mg/kg(R^(2)=0.997),and the detection limit was 1.52 mg/kg(3σ/K,n=9).The established method was applied to Hx detection in bass,grass carp,and shrimp,and the data were verified by HPLC.The result shows that the established probe is sensitive,accurate,and reliable,and can be used for Hx detection in aquatic products.
基金financially supported by the Korea Institute of Energy Research(KIER)(grant no.C3-2401,2402,2403)the National Research Foundation(grant no.2022M3J1A1063019)funded by the Ministry of Science and ICT
文摘To demonstrate flexible and tandem device applications,a low-temperature Cu_(2)ZnSnSe_(4)(CZTSe)deposition process,combined with efficient alkali doping,was developed.First,high-quality CZTSe films were grown at 480℃by a single co-evaporation,which is applicable to polyimide(PI)substrate.Because of the alkali-free substrate,Na and K alkali doping were systematically studied and optimized to precisely control the alkali distribution in CZTSe.The bulk defect density was significantly reduced by suppression of deep acceptor states after the(NaF+KF)PDTs.Through the low-temperature deposition with(NaF+KF)PDTs,the CZTSe device on glass yields the best efficiency of 8.1%with an improved Voc deficit of 646 mV.The developed deposition technologies have been applied to PI.For the first time,we report the highest efficiency of 6.92%for flexible CZTSe solar cells on PI.Additionally,CZTSe devices were utilized as bottom cells to fabricate four-terminal CZTSe/perovskite tandem cells because of a low bandgap of CZTSe(~1.0 eV)so that the tandem cell yielded an efficiency of 20%.The obtained results show that CZTSe solar cells prepared by a low-temperature process with in-situ alkali doping can be utilized for flexible thin-film solar cells as well as tandem device applications.
文摘Integrating selective organic synthesis with hydrogen(H_(2))evolution in one photocatalytic redox reaction system sheds light on the underlying approach for concurrent employment of photogenerated electrons and holes towards efficient production of solar fuels and chemicals.In this work,a facile one‐pot oil bath method has been proposed to fabricate a noble metal‐free ultrathin Ni‐doped ZnIn_(2)S_(4)(ZIS/Ni)composite nanosheet for effective solar‐driven selective dehydrocoupling of benzyl alcohol into value‐added C–C coupled hydrobenzoin and H_(2) fuel,which exhibits higher performance than pure ZIS nanosheet.The remarkably improved photoredox activity of ZIS/Ni is mainly attributed to the optimized electron structure featuring narrower band gap and suitable energy band position,which facilitates the ability of light harvesting and photoexcited charge carrier separation and transfer.Furthermore,it has been demonstrated that it is feasible to employ ZIS/Ni for various aromatic alcohols dehydrocoupling to the corresponding C–C coupled products.It is expected that this work can stimulate further interest on the establishment of innovative photocatalytic redox platform coupling clean solar fuels synthesis and selective organic conversion in a sustainable manner.
基金Project supported by the Science and Technology Program of Guangdong Province,China(Grant No.2015B010112002)the Science and Technology Project of Guangzhou City,China(Grant No.201607010250)
文摘The electronic structures and optical properties of β-Ga_2O_3 and Si-and Sn-doped β-Ga_2O_3 are studied using the GGA + U method based on density functional theory. The calculated bandgap and Ga 3d-state peak of β-Ga_2O_3 are in good agreement with experimental results. Si-and Sn-doped β-Ga_2O_3 tend to form under O-poor conditions, and the formation energy of Si-doped β-Ga_2O_3 is larger than that of Sn-doped β-Ga_2O_3 because of the large bond length variation between Ga–O and Si–O. Si-and Sn-doped β-Ga_2O_3 have wider optical gaps than β-Ga_2O_3, due to the Burstein–Moss effect and the bandgap renormalization effect. Si-doped β-Ga_2O_3 shows better electron conductivity and a higher optical absorption edge than Sn-doped β-Ga_2O_3, so Si is more suitable as a dopant of n-type β-Ga_2O_3, which can be applied in deep-UV photoelectric devices.
文摘Nd^(3+)-doped NaGdF_(4):Yb,Tm nanocrystals were synthesized by an improved high-temperature thermal decomposition method,and the effects of doping concentrations on the crystal structure,phase composition,and upconverted fluorescence intensity were also investigated.The results reveal that the introduction of Nd^(3+) ions does not cause the transformation of the crystal phase,but induce the change of the unit cell parameters.Meanwhile,the fluorescence intensity of the synthesized nanocrystals when co-doped with 3 mol%Nd^(3+) is the strongest under the excitation of 980 nm laser,which is 3.9 times that of the Nd^(3+)-free doped nanoparticles,and the average size is 62.9 nm.And it is located in the blue area of the CIE coordinate diagram,and the corresponding color purity is 91.81%under the same experimental conditions.The resulting nanocrystals show the potential as excellent fluorescence labeling and in vivo imaging probes.
