Electrochromic materials are of great interest for their potential in eyewear protection and data storage devices, as they change colors in response to electrochemical switching. While many of the systems currently us...Electrochromic materials are of great interest for their potential in eyewear protection and data storage devices, as they change colors in response to electrochemical switching. While many of the systems currently used are based on inorganic materials, organic materials such as triazenes have emerged as viable alternatives due to their unique properties, including optical properties. Triazenes are a class of organic compounds with three consecutive nitrogen atoms in an acyclic arrangement, and they have been used for a variety of applications in medicinal and synthetic chemistry. However, the effects of solvents on the UV-visible absorption spectrum of triazenes have not been fully investigated. The neutral molecules of 3,3-diisopropyl-1-phenyltriazene and 1-(4-chlorophenyl)-3-cyclopentyltriazene in acetonitrile, the UV-visible spectra corresponded respectively to HOMO → LUMO transitions with a large maximum absorption at 299.74 nm (4.1364 eV) and 299.57 nm (4.1387 eV) and the most intense oscillator strength (f = 0.6988) and (f = 0.7372). These results suggest that the electronic transitions of the compounds are highly influenced by the nature of the substituents on the triazene unit, as well as the solvent used in the experiment. The redox couple 0.92 and -0.44 V/Ag/AgCl is attributed to the phenyl group. Compound III showed an oxidation and reduction peak respectively -0.27 and -0.8 V/Ag/AgCl attributed to the phenyl molecule. The study concluded that all three compounds were electroactive and exhibited reversible characteristics with oxidizing/reducing couples. This study aims to contribute to research on the optical properties of triazenes compounds and the application of quantum chemical calculation methods for understanding their molecular structures. By investigating the solute-solvent interactions occurring in the solvation shell of the solutes, we aim to gain insights into the effects of solvents on the UV-visible absorption spectrum of triazenes. Our findings may have implications for the development of functionalized triazenes as potential electrochromic materials.展开更多
A novel neonicotinoid analogue(C13H19N5O5,3a)had been synthesized,the structure was characterized by elemental analysis,IR and 1H NMR spectra,and the S-(+)-(E)-configuration was confirmed by single-crystal X-ra...A novel neonicotinoid analogue(C13H19N5O5,3a)had been synthesized,the structure was characterized by elemental analysis,IR and 1H NMR spectra,and the S-(+)-(E)-configuration was confirmed by single-crystal X-ray diffraction.The crystal belongs to monoclinic,space group P21 with a = 8.7076(17),b = 8.3211(17),c = 10.642(2),β = 92.370(3)o,V = 770.4(3)3,Z = 2,Dc = 1.402 g/cm3,μ = 0.110 mm-1,Mr = 325.33,F(000)= 344,S = 1.027,R = 0.0543 and wR = 0.1229 for 3601 unique reflections with 2919 observed ones(I 2σ(I)).Compound 3a is stabilized by intramolecular hydrogen bonds and intermolecular force.In addition,the structure of compound 3a was optimized by the B3LYP/6-31G(d,p).DFT/B3LYP optimizations were performed based on X-ray geometries applying 6-31G(d,p)basis set.The optimized structure of compound 3a by the B3LYP/6-31G(d,p)method is more bent than in the crystal.IR spectrum of the solid compound is consistent with the X-ray structure.The HOMO-LUMO gap in 3a(5.3 eV)indicates high kinetic stabilities of compound 3a.The preliminary bioassay test showed that 3a exhibited good activities against Nilaparvata legen,Pseudaletia separate Walker and Aphis medicagini at 500 mg/L.展开更多
A novel copper(Ⅱ) complex with tert-butyl 2-[N-(tert-butyloxycarbonylmethyl)-2-picolyamino]acetate(ampy) was synthesized and structurally characterized by elemental analysis, FT-IR spectrum, electrospray ioniza...A novel copper(Ⅱ) complex with tert-butyl 2-[N-(tert-butyloxycarbonylmethyl)-2-picolyamino]acetate(ampy) was synthesized and structurally characterized by elemental analysis, FT-IR spectrum, electrospray ionization-mass spectrometry, UV-vis spectrum and single-crystal X-ray diffraction, respectively. A mononuclear copper(II) complex with ampy, [Cu(ampy)Cl2](1), was formed irrespective of the metal-to-ligand molar ratios([Cu2+]:[ampy] = 0.5:1, 1:1, and 2:1) as a single product. Complex 1 crystallizes in the orthorhombic system, space group Pbca with a = 12.343(2), b = 18.928(3), c = 20.058(4) A, V = 4686.1(14) A3, Z = 8, Dc = 1.3349(4) g/cm3, F(000) = 1920, S = 1.016, R = 0.0693 and w R = 0.1721 for 3151 observed reflections with I 〉 2σ(I). X-ray diffraction analysis reveals that the central copper(II) ion is bound by pyridyl N, tertiary amine N and carbonyl O atoms of the quadridentate ampy as well as two Cl anions, constructing a slightly distorted octahedral geometry. Complex 1 further constructs a stable 3D supramolecular architecture by intermolecular C–H…Cl hydrogen bonds. In addition, the molecular geometry was calculated by density functional theory(DFT/B3LYP) method with the basis sets(6-31+G(d,p) for H, C, N, O and Cl atoms, and LANL2 DZ for Cu atom, respectively). The calculated results show that the optimized geometrical parameters are in good agreement with the experimental data. Natural bond orbital(NBO) analysis and frontier molecular orbitals(FMOs) analysis were investigated at the same level.展开更多
As persulfate(S_(2)O_(8)^(2-))is being increasingly used as an alternative oxidizing agent,developing lowcost and eco-friendly catalysts for efficient S_(2)O_(8)^(2-)activation is potentially useful for the treatment ...As persulfate(S_(2)O_(8)^(2-))is being increasingly used as an alternative oxidizing agent,developing lowcost and eco-friendly catalysts for efficient S_(2)O_(8)^(2-)activation is potentially useful for the treatment of wastewater containing refractory organic pollutant.In this study,the degradative features and mechanisms of carbamazepine(CBZ)were systematically investigated in a novel FeS-S_(2)O_(8)^(2-)process under near-neutral conditions.The results exhibited that CBZ can be effectively eliminated by the FeS-S_(2)O_(8)^(2-)process and the optimal conditions were:250 mg/L FeS,0.5 mmol/L S_(2)O_(8)^(2-),and pH=6.0.The existence of Cl^(−)(1 and 50 mmol/L)has little influence on the CBZ elimination,while both HCO_(3)^(−) and HPO_(4)^(2−)(1 and 50 mmol/L)significantly suppressed the CBZ removal in the FeS-S_(2)O_(8)^(2-)process.CBZ could be degraded via a radical mechanism in the FeS-S_(2)O_(8)^(2-)process,the working radical species(i.e.,SO_(4)•−and•OH)were efficiently formed via the promoted decomposition of S_(2)O_(8)^(2-)by the surface Fe2+on the FeS and the dissolved ferrous ions in solution.Based on the identified oxidized products and Fukui index calculations,a possible degradation pathway of CBZ was speculated.More importantly,a two-stage oxidation mechanism of CBZ elimination was speculated in the FeS-S_(2)O_(8)^(2-)process,the activation of S_(2)O_(8)^(2-)by the surface-active Fe(II)of FeS dominated in the initial 5 min,while homogeneous oxidation reactions played more essential parts than others in the following reaction stage(5–60 min).Overall,this study demonstrated that the FeS-S_(2)O_(8)^(2-)process is capable of removing CBZ from water efficiently.展开更多
Carbon-based single-atom catalysts(SACs) with atomic sizes of active sites have become the promising candidates for a variety of catalytic systems because of their high atom utilization, and unique electronic structur...Carbon-based single-atom catalysts(SACs) with atomic sizes of active sites have become the promising candidates for a variety of catalytic systems because of their high atom utilization, and unique electronic structures. Different types of single-atom sites can be fabricated via multiple preparation strategies, which would demonstrate distinct different coordination configurations and electronic features, and ultimately affected the structure-catalysis relationship of SACs in targeted reactions. As a result, it is necessary to identify the active sites of SACs and understand the structure-catalysis relationship of SACs at the atomic scale. In this review, a variety of preparation strategies of carbon-based SACs were documented. Then, the recent development on versatile characterization techniques and computational achievements were summarized regarding in understanding the electronic and geometric characteristics of carbon-based SACs.Finally, major challenges and development directions concerning single-atom sites identification and advanced tools development are discussed to shed light on future research of carbon-based SACs.展开更多
3d transition metals doped CuGaS2 are considered as possible absorbing material candidates for intermediated band thin film solar cells. The electronic structure and optical properties of 3d transition metals doped Cu...3d transition metals doped CuGaS2 are considered as possible absorbing material candidates for intermediated band thin film solar cells. The electronic structure and optical properties of 3d transition metals doped CuGaS2 are investigated by using density functional theory calculations with the GGA + U method in the present work. The doping with 3d transition metals does not obviously change the crystal structure, band gap, and optical absorption edge of the CuGaS2 host. However, in the case of CuGa1-χTMχS2 (TM = Ti, V, Cr, Fe, and Ni), there is at least one distinct isolated impurity energy level in the band gap, and the optical absorption is enhanced in the ultraviolet-light region. Therefore, these materials are band thin film solar ceils. The calculated results are very well better explain them. ideal absorber material candidates for intermediated consistent with experimental observations, and could better explain them.展开更多
In this work,the impact of the doping process on the photoluminescence emission of CaWO_(4) as a function of the concentration of Eu^(3+) cation(0.01 mol%,0.02 mol%,0.04 mol%,0.06 mol%,0.08 mol%,and 0.10 mol%) is disc...In this work,the impact of the doping process on the photoluminescence emission of CaWO_(4) as a function of the concentration of Eu^(3+) cation(0.01 mol%,0.02 mol%,0.04 mol%,0.06 mol%,0.08 mol%,and 0.10 mol%) is discussed in detail.Ca_(1-x)WO~4:xEu^(3+) samples were successfully synthesized by a simple coprecipitation method followed by microwave irradiation.The blue shift in the absorption edge confirms the quantum confinement effect and the band gap energy covers the range from 3.91 to 4.18 eV,as the amount of Eu^(3+) cations increases.The experimental results are sustained by first-principles calculations,at the density functional theory level,to decipher the geometry and electronic properties,thereby enabling a more accurate and direct comparison between theory and experiment for the Ca_(1-x)WO_(4):xEu^(3+) structure.展开更多
Acetaminophen(ACE)is commonly used in analgesic and antipyretic drug,which is hardly removed by traditional wastewater treatment processes.Herein,amorphous Co(OH)_(2)nanocages were explored as peroxymonosulfate(PMS)ac...Acetaminophen(ACE)is commonly used in analgesic and antipyretic drug,which is hardly removed by traditional wastewater treatment processes.Herein,amorphous Co(OH)_(2)nanocages were explored as peroxymonosulfate(PMS)activator for efficient degradation of ACE.In the presence of amorphous Co(OH)_(2)nanocages,100%of ACE removal was reached within 2 min with a reaction rate constant k_(1)=3.68 min 1 at optimum pH 5,which was much better than that of crystallineβ-Co(OH)_(2)and Co_(3)O_(4).Amorphous materials(disorder atom arrangement)with hollow structures possess large specific surface area,more reactive sites,and abundant vacancies structures,which could efficiently facilitate the catalytic redox reactions.The radicals quenching experiment demonstrated that SO_(4)^(·-)radicals dominated the ACE degradation rather than^(·)OH radicals.The mechanism of ACE degradation was elucidated by the an alysis of degradation in termediates and theoretical calculation,indicating that the electrophilic SO_(4)^(·-)and^(·)OH tend to attack the atoms of ACE with high Fukui index(f).Our finding highlights the remarkable advantages of amorphous materials as heterogeneous catalysts in sulfate radicals-based AOPs and sheds new lights on water treatment for the degradation of emerging organic contaminants.展开更多
Four novel 2-methoxyimino phenylacetate derivatives containing 1,3,4-oxadiazole ring were designed and synthesized from the key intermediate of Trifloxystrobin or Azoxystrobin via intermediate derivatization and activ...Four novel 2-methoxyimino phenylacetate derivatives containing 1,3,4-oxadiazole ring were designed and synthesized from the key intermediate of Trifloxystrobin or Azoxystrobin via intermediate derivatization and active structure splicing.The chemical structures of the target compounds were confirmed by]H NMR,13C NMR and elemental analysis.The crystal structure of methyl(E)-2-(methoxyimino)-2-(2-(((5-((4-methoxyphenoxy)methyl)-1,3,4-oxadiazol-2-yl)thio)methyl)phenyl)acetate(Al)was determined by single-crystal X-ray diffraction.Compound A1 belongs to triclinic system,space group Pi with two molecules in each unit cell.The benzene ring plane C(2)-C(3)-C(4)-C(5)-C(6)-C(7)and oxazole ring plane are nearly parallel with the dihedral angle of 6.4°.The benzene ring plane C(12)-C(13)-C(14)-C(15)-C(16)-C(17)and oxazole ring plane are not perpendicular with the dihedral angle of 49.4°.The crystal of compound Al is stabilized by π-π stacking interactions.The fungicidal activities of the target compounds against four plant pathogenic fungi in vitro were tested,and some of them had good activities.The DFT calculation was carried out to study the structure-activity relationship of the title derivatives using Gasian 09 and Multiwfii 3.6.展开更多
Two new fluorinated phenylisoquinoline-based iridium(Ⅲ) complexes,[Ir(f2piq)2(bipy)][PF6](3a) and[Ir(fmpiq)2(bipy)][PF6](3b)(f2piq = l-(2,4-difluorophenyl)isoquinoline,fmpiq = 1-(4-fluoro-2-methylph...Two new fluorinated phenylisoquinoline-based iridium(Ⅲ) complexes,[Ir(f2piq)2(bipy)][PF6](3a) and[Ir(fmpiq)2(bipy)][PF6](3b)(f2piq = l-(2,4-difluorophenyl)isoquinoline,fmpiq = 1-(4-fluoro-2-methylphenyl)isoquinoline,bipy = 2,2'-bipyridine),have been synthesized and fully characterized.Single crystal X-ray diffraction study has been undertaken on complexes 3a and 3b,which show that each adopts the distorted octahedral coordination geometry with the cis-C,C' and trans-N,N' configuration.The photoluminescence spectra of 3a and 3b exhibit yellow and orange emission maxima at 584 and 600 nm,respectively.The frontier molecular orbital diagrams and the lowest-energy electronic transitions of 3a-3b have been calculated with density functional theory(DFT) and time-dependent DFT(TD-DFT).The absorption and emission spectra of complex 3b is red-shifted relative to those of complex 3a,as a consequence of the nature of the methyl group.展开更多
We have developed an N-heterocyclic carbene(NHC)-catalyzed domino reaction with aryl alde-hyde through a simple acyl azolium intermediate using phenyliodine(III)diacetate(PIDA)as an oxi-dant.Controlled experiments and...We have developed an N-heterocyclic carbene(NHC)-catalyzed domino reaction with aryl alde-hyde through a simple acyl azolium intermediate using phenyliodine(III)diacetate(PIDA)as an oxi-dant.Controlled experiments and density functional theory calculations supported a domino two-stage mechanism from aldehyde/amine to anα-oxygen-ation product,including NHC-catalyzed oxidation of the aldehyde to carboxylic acid via acyl azolium intermediate,and further,an addition of carboxyl-ate to iminium intermediate.Our study reveals a new model for the oxidation of Breslow intermedi-ate via electrophilic attack of the hydroxyl group by PIDA.展开更多
P-xylene(p-C_(8)H_(10))is extremely harmful and dangerous to human health due to high toxicity and strong carcinogenicity.Exploring sensitive material to effectively detect p-xylene is of importance.In this paper,pero...P-xylene(p-C_(8)H_(10))is extremely harmful and dangerous to human health due to high toxicity and strong carcinogenicity.Exploring sensitive material to effectively detect p-xylene is of importance.In this paper,perovskite single crystal(C_(4)H_(9)NH_(3))_(2)PbI_(4) has been successfully synthesized via solution method.The obtained product was analyzed by single crystal X-ray diffraction.With the space group Pbca,orthorhombic(C_(4)H_(9)NH_(3))_(2)PbI_(4) layered perovskite structure consists of an extended two-dimensional network of corner-sharing PbI_(6) octahedron.Single layer perovskite sheets of distorted PbI_(6) octahedron alternated with protonated n-butylammonium cation bilayers,which offers many advantages and provides the possibility of forming a gas sensor device based on the change of resistances.Density functional theory(DFT)simulations regarding the adsorption energy revealed that this organicinorganic hybrid perovskite compound has excellent selectivity toward p-xylene compared with other gases including C_(2)H_(5)OH,C_(6)H_(6),CH_(2)Cl_(2),HCHO,CH_(3)COCH_(3) and C_(7)H_(8).The calculation of electron density,density of states and electron density difference showed the sensing mechanism of p-C_(8)H_(10) is mainly derived from physical adsorption-desorption in view of electron transfer.展开更多
Two new 1,3-dithiole derivatives, 4,4'-{9-[4,5-bis(methylthio)-1,3-dithiol-2-ylidene]-9H-fluorene-2,7- diyl} dipyridine(2a) and 3,3'-{9-[4,5-bis(methylthio)-1,3-dithiol-2-ylidene]-9H-fluorene-2,7-diyl} dipyrid...Two new 1,3-dithiole derivatives, 4,4'-{9-[4,5-bis(methylthio)-1,3-dithiol-2-ylidene]-9H-fluorene-2,7- diyl} dipyridine(2a) and 3,3'-{9-[4,5-bis(methylthio)-1,3-dithiol-2-ylidene]-9H-fluorene-2,7-diyl} dipyridine(2b) were synthesized and characterized by Fourier transform infrared(FTIR), 1H NMR, 13C NMR and mass spectroscopies. The crystal structure of compound 2b was also studied. The optimized conformations and molecular orbital diagrams of compounds 2a and 2b were illustrated via density functional theory(DFT). By the time-dependent DFT(TD-DFT) method, electronic absorption spectra of compounds 2a and 2b were predicted and the results achieved were in good agreement with the experimental data. The formation of the cationic radical during the electrochemical oxidation process was also proposed.展开更多
The sluggish kinetics of the electrochemical oxygen reduction reaction(ORR)in intermediatetemperature solid oxide fuel cells(IT-SOFCs)greatly limits the overall cell performance.In this study,an efficient and durable ...The sluggish kinetics of the electrochemical oxygen reduction reaction(ORR)in intermediatetemperature solid oxide fuel cells(IT-SOFCs)greatly limits the overall cell performance.In this study,an efficient and durable cathode material for IT-SOFCs is designed based on density functional theory(DFT)calculations by co-doping with Nb and Ta the B-site of the SrFeO_(3-δ)perovskite oxide.The DFT calculations suggest that Nb/Ta co-doping can regulate the energy band of the parent SrFeO_(3-δ)and help electron transfer.In symmetrical cells,such cathode with a SrFe_(0.8)Nb_(0.1)Ta_(0.1)O_(3-δ)(SFNT)detailed formula achieves a low cathode polarization resistance of 0.147Ωcm^(2) at 650℃.Electron spin resonance(ESR)and X-ray photoelectron spectroscopy(XPS)analysis confirm that the co-doping of Nb/Ta in SrFeO_(3-δ)B-site increases the balanced concentration of oxygen vacancies,enhancing the electrochemical performance when compared to 20 mol%Nb single-doped perovskite oxide.The cathode button cell with NiSDC|SDC|SFNT configuration achieves an outstanding peak power density of 1.3 W cm^(-2)at 650℃.Moreover,the button cell shows durability for 110 h under 0.65 V at 600℃ using wet H_(2) as fuel.展开更多
Developing efficient and stable cathodes for low-temperature solid oxide fuel cells(LT-SOFCs) is of great importance for the practical commercialization.Herein,we propose a series of Sm-modified Bi_(0.7-x)Sm_xSr_(0.3)...Developing efficient and stable cathodes for low-temperature solid oxide fuel cells(LT-SOFCs) is of great importance for the practical commercialization.Herein,we propose a series of Sm-modified Bi_(0.7-x)Sm_xSr_(0.3)FeO_(3-δ) perovskites as highly-active catalysts for LT-SOFCs.Sm doping can significantly enhance the electrocata lytic activity and chemical stability of cathode.At 600℃,Bi_(0.675)Sm_(0.025)Sr_(0.3)FeO_(3-δ)(BSSF25) cathode has been found to be the optimum composition with a polarization resistance of 0.098 Ω cm^2,which is only around 22.8% of Bi_(0.7)Sr_(0.3)FeO_(3-δ)(BSF).A full cell utilizing BSSF25 displays an exceptional output density of 790 mW cm^(-2),which can operate continuously over100 h without obvious degradation.The remarkable electrochemical performance observed can be attributed to the improved O_(2) transport kinetics,superior surface oxygen adsorption capacity,as well as O_(2)p band centers in close proximity to the Fermi level.Moreover,larger average bonding energy(ABE) and the presence of highly acidic Bi,Sm,and Fe ions restrict the adsorption of CO_(2) on the cathode surface,resulting in excellent CO_(2) resistivity.This work provides valuable guidance for systematic design of efficient and durable catalysts for LT-SOFCs.展开更多
The interface mechanism between catalyst and carbon substrate has been the focus of research.In this paper,the FeCo alloy embedded N,S co-doped carbon substrate bifunctional catalyst(FeCo/S-NC)is obtained by a simple ...The interface mechanism between catalyst and carbon substrate has been the focus of research.In this paper,the FeCo alloy embedded N,S co-doped carbon substrate bifunctional catalyst(FeCo/S-NC)is obtained by a simple one-step pyrolysis strategy.The experimental results and density functional theory(DFT)calculation show that the formation of FeCo alloy is conducive to promoting electron transfer,and the introduction of S atom can enhance the interaction between FeCo alloy and carbon substrate,thus inhibiting the migration and agglomeration of particles on the surface of carbon material.The FeCo/SNC catalysts show outstanding performance for oxygen reduction reaction(ORR)and oxygen evolution reaction(OER).FeCo/S-NC shows a high half-wave potential(E_(1/2)=0.8823 V)for ORR and a low overpotential at 10 mA cm^(-2)(E_(j=10)=299 mV)for OER.In addition,compared with Pt/C+RuO_(2) assembled Zn-air battery(ZAB),the FeCo/S-NC assembled ZAB exhibits a larger power density(198.8 mW cm^(-2)),a higher specific capacity(786.1 mA h g_(zn)~(-1)),and ultra-stable cycle performance.These results confirm that the optimized composition and the interfacial interaction between catalyst and carbon substrate synergistically enhance the electrochemical performance.展开更多
The nickel-rich layered cathode material LiNi_(0.8)Co_(0.1)Mn_(0.1)O_(2)(NCM811)has high energy density,lower cost and is a promising cathode material currently under development.However,its electrochemical and struct...The nickel-rich layered cathode material LiNi_(0.8)Co_(0.1)Mn_(0.1)O_(2)(NCM811)has high energy density,lower cost and is a promising cathode material currently under development.However,its electrochemical and structural stability is poor during cycling.Among the many modification methods,cation doping has been consistently proven to be an effective strategy for enhancing electrochemical performance.Herein,the NCM811 cathode material was modified by solid-phase reactions with Mg and Al doped.In addition,the corresponding mechanism of NCM811 cathode material-doped modification is explored by density functional theory(DFT)calculations,and we have extended this approach to other ternary cathode materials with different ratios and obtained universal laws.Combined with DFT calculations,the results show that Mg2+occupies the Li+site and reduces the degree of Li^(+)/Ni^(2+) mixture;Al^(3+) acts as a structural support during charging and discharging to prevent structural collapse.The electrochemical properties were tested by an electrochemical workstation and the LAND system,and the results showed that the capacity retention rate increased to varying degrees from 63.66%to 69.87%and 89.05%for NCM811-Mg and NCM811-Al at room temperature after 300 cycles,respectively.This study provides a theoretical basis and design strategy for commercializing cationic-doped modification of nickel-rich cathode materials.展开更多
Urea generation through electrochemical CO_(2) and NO_(3)~-co-reduction reaction(CO_(2)NO_(3)RR)is still limited by either the low selectivity or yield rate of urea.Herein,we report copper carbonate hydroxide(Cu_2(OH)...Urea generation through electrochemical CO_(2) and NO_(3)~-co-reduction reaction(CO_(2)NO_(3)RR)is still limited by either the low selectivity or yield rate of urea.Herein,we report copper carbonate hydroxide(Cu_2(OH)_2CO_(3))as an efficient CO_(2)NO_(3)RR electrocatalyst with an impressive urea Faradaic efficiency of45.2%±2.1%and a high yield rate of 1564.5±145.2μg h~(-1)mg_(cat)~(-1).More importantly,H_(2) evolution is fully inhibited on this electrocatalyst over a wide potential range between-0.3 and-0.8 V versus reversible hydrogen electrode.Our thermodynamic simulation reveals that the first C-N coupling follows a unique pathway on Cu_2(OH)_2CO_(3) by combining the two intermediates,~*COOH and~*NHO.This work demonstrates that high selectivity and yield rate of urea can be simultaneously achieved on simple Cu-based electrocatalysts in CO_(2)NO_(3)RR,and provide guidance for rational design of more advanced catalysts.展开更多
Solving the problems of low electrical conductivity and poor cycling durability in transition metal oxidesbased anode materials for lithium-ion batteries(LIBs)and sodium-ion batteries(SIBs)has already turned into an u...Solving the problems of low electrical conductivity and poor cycling durability in transition metal oxidesbased anode materials for lithium-ion batteries(LIBs)and sodium-ion batteries(SIBs)has already turned into an urgent requirement.In this paper,we successfully synthesized Co_(2)VO_(4)/Co compounds with Co-VMOF(metal-organic framework)as a sacrificial template and investigated their electrochemical mechanism in order to improve the electrochemical properties of LIBs and SIBs.The optimized heaping configuration and the existence of metallic Co catalyzed the formation of radical ions,thereby facilitating higher conductivity,shortening Li+and Na+transport paths,and providing more active sites.Co_(2)VO_(4)/Co constructed with 2-methylimidazole as a ligand showed a discharge capacity of 1605.1 mA h g^(-1)after 300 cycles at 0.1 A g^(-1)in LIB and 677.2 mA h g^(-1)in SIB.Density functional theory(DFT)calculation emphasizes the crucial role of Co_(2)VO_(4)/Co in enhancing electrode conductivity,decreasing the migratory energy barrier,and thereby strengthening electrochemical properties.This heterostructure building technique may pave the way for the development of high-performance LIBs and SIBs.Furthermore,the problem of the low first-loop coulombic efficiency faced by transition metal oxides is improved.展开更多
This study investigates the effects of Fe on the oxygen-evolution reaction(OER)in the presence of Au.Two distinct areas of OER were identified:the first associated with Fe sites at low overpotential(~330 mV),and the s...This study investigates the effects of Fe on the oxygen-evolution reaction(OER)in the presence of Au.Two distinct areas of OER were identified:the first associated with Fe sites at low overpotential(~330 mV),and the second with Au sites at high overpotential(~870 mV).Various factors such as surface Fe concentration,electrochemical method,scan rate,potential range,concentration,method of adding K_(2)Fe O_(4),nature of Fe,and temperature were varied to observe diverse behaviors during OER for Fe O_(x)H_(y)/Au.Trace amounts of Fe ions had a significant impact on OER,reaching a saturation point where the activity did not increase further.Strong electronic interaction between Fe and Au ions was indicated by X-ray photoelectron spectroscopy(XPS)and electron paramagnetic resonance(EPR)analyses.In situ visible spectroscopy confirmed the formation of Fe O_(4)^(2-)during OER.In situ Mossbauer and surfaceenhanced Raman spectroscopy(SERS)analyses suggest the involvement of Fe-based species as intermediates during the rate-determining step of OER.A lattice OER mechanism based on Fe O_(x)H_(y)was proposed for operation at low overpotentials.Density functional theory(DFT)calculations revealed that Fe oxide,Fe-oxide clusters,and Fe doping on the Au foil exhibited different activities and stabilities during OER.The study provides insights into the interplay between Fe and Au in OER,advancing the understanding of OER mechanisms and offering implications for the design of efficient electrocatalytic systems.展开更多
文摘Electrochromic materials are of great interest for their potential in eyewear protection and data storage devices, as they change colors in response to electrochemical switching. While many of the systems currently used are based on inorganic materials, organic materials such as triazenes have emerged as viable alternatives due to their unique properties, including optical properties. Triazenes are a class of organic compounds with three consecutive nitrogen atoms in an acyclic arrangement, and they have been used for a variety of applications in medicinal and synthetic chemistry. However, the effects of solvents on the UV-visible absorption spectrum of triazenes have not been fully investigated. The neutral molecules of 3,3-diisopropyl-1-phenyltriazene and 1-(4-chlorophenyl)-3-cyclopentyltriazene in acetonitrile, the UV-visible spectra corresponded respectively to HOMO → LUMO transitions with a large maximum absorption at 299.74 nm (4.1364 eV) and 299.57 nm (4.1387 eV) and the most intense oscillator strength (f = 0.6988) and (f = 0.7372). These results suggest that the electronic transitions of the compounds are highly influenced by the nature of the substituents on the triazene unit, as well as the solvent used in the experiment. The redox couple 0.92 and -0.44 V/Ag/AgCl is attributed to the phenyl group. Compound III showed an oxidation and reduction peak respectively -0.27 and -0.8 V/Ag/AgCl attributed to the phenyl molecule. The study concluded that all three compounds were electroactive and exhibited reversible characteristics with oxidizing/reducing couples. This study aims to contribute to research on the optical properties of triazenes compounds and the application of quantum chemical calculation methods for understanding their molecular structures. By investigating the solute-solvent interactions occurring in the solvation shell of the solutes, we aim to gain insights into the effects of solvents on the UV-visible absorption spectrum of triazenes. Our findings may have implications for the development of functionalized triazenes as potential electrochromic materials.
基金supported by the National Natural Science Foundation of China (21042010)the Key Laboratory of Rare Earth Functional Materials of Shanghai (07dz22303)the Key Scientific and Technological Project of Shanghai (09391912100)
文摘A novel neonicotinoid analogue(C13H19N5O5,3a)had been synthesized,the structure was characterized by elemental analysis,IR and 1H NMR spectra,and the S-(+)-(E)-configuration was confirmed by single-crystal X-ray diffraction.The crystal belongs to monoclinic,space group P21 with a = 8.7076(17),b = 8.3211(17),c = 10.642(2),β = 92.370(3)o,V = 770.4(3)3,Z = 2,Dc = 1.402 g/cm3,μ = 0.110 mm-1,Mr = 325.33,F(000)= 344,S = 1.027,R = 0.0543 and wR = 0.1229 for 3601 unique reflections with 2919 observed ones(I 2σ(I)).Compound 3a is stabilized by intramolecular hydrogen bonds and intermolecular force.In addition,the structure of compound 3a was optimized by the B3LYP/6-31G(d,p).DFT/B3LYP optimizations were performed based on X-ray geometries applying 6-31G(d,p)basis set.The optimized structure of compound 3a by the B3LYP/6-31G(d,p)method is more bent than in the crystal.IR spectrum of the solid compound is consistent with the X-ray structure.The HOMO-LUMO gap in 3a(5.3 eV)indicates high kinetic stabilities of compound 3a.The preliminary bioassay test showed that 3a exhibited good activities against Nilaparvata legen,Pseudaletia separate Walker and Aphis medicagini at 500 mg/L.
基金supported by the National Basic Research Program of China(No.2014CB643401)the National Natural Science Foundation of China(Nos.51134007 and 51474256)
文摘A novel copper(Ⅱ) complex with tert-butyl 2-[N-(tert-butyloxycarbonylmethyl)-2-picolyamino]acetate(ampy) was synthesized and structurally characterized by elemental analysis, FT-IR spectrum, electrospray ionization-mass spectrometry, UV-vis spectrum and single-crystal X-ray diffraction, respectively. A mononuclear copper(II) complex with ampy, [Cu(ampy)Cl2](1), was formed irrespective of the metal-to-ligand molar ratios([Cu2+]:[ampy] = 0.5:1, 1:1, and 2:1) as a single product. Complex 1 crystallizes in the orthorhombic system, space group Pbca with a = 12.343(2), b = 18.928(3), c = 20.058(4) A, V = 4686.1(14) A3, Z = 8, Dc = 1.3349(4) g/cm3, F(000) = 1920, S = 1.016, R = 0.0693 and w R = 0.1721 for 3151 observed reflections with I 〉 2σ(I). X-ray diffraction analysis reveals that the central copper(II) ion is bound by pyridyl N, tertiary amine N and carbonyl O atoms of the quadridentate ampy as well as two Cl anions, constructing a slightly distorted octahedral geometry. Complex 1 further constructs a stable 3D supramolecular architecture by intermolecular C–H…Cl hydrogen bonds. In addition, the molecular geometry was calculated by density functional theory(DFT/B3LYP) method with the basis sets(6-31+G(d,p) for H, C, N, O and Cl atoms, and LANL2 DZ for Cu atom, respectively). The calculated results show that the optimized geometrical parameters are in good agreement with the experimental data. Natural bond orbital(NBO) analysis and frontier molecular orbitals(FMOs) analysis were investigated at the same level.
基金the National Natural Science Foundation of China(No.52100060)the Natural Science Foundation of Hubei Province,China(No.2020CFB383)for the financial support。
文摘As persulfate(S_(2)O_(8)^(2-))is being increasingly used as an alternative oxidizing agent,developing lowcost and eco-friendly catalysts for efficient S_(2)O_(8)^(2-)activation is potentially useful for the treatment of wastewater containing refractory organic pollutant.In this study,the degradative features and mechanisms of carbamazepine(CBZ)were systematically investigated in a novel FeS-S_(2)O_(8)^(2-)process under near-neutral conditions.The results exhibited that CBZ can be effectively eliminated by the FeS-S_(2)O_(8)^(2-)process and the optimal conditions were:250 mg/L FeS,0.5 mmol/L S_(2)O_(8)^(2-),and pH=6.0.The existence of Cl^(−)(1 and 50 mmol/L)has little influence on the CBZ elimination,while both HCO_(3)^(−) and HPO_(4)^(2−)(1 and 50 mmol/L)significantly suppressed the CBZ removal in the FeS-S_(2)O_(8)^(2-)process.CBZ could be degraded via a radical mechanism in the FeS-S_(2)O_(8)^(2-)process,the working radical species(i.e.,SO_(4)•−and•OH)were efficiently formed via the promoted decomposition of S_(2)O_(8)^(2-)by the surface Fe2+on the FeS and the dissolved ferrous ions in solution.Based on the identified oxidized products and Fukui index calculations,a possible degradation pathway of CBZ was speculated.More importantly,a two-stage oxidation mechanism of CBZ elimination was speculated in the FeS-S_(2)O_(8)^(2-)process,the activation of S_(2)O_(8)^(2-)by the surface-active Fe(II)of FeS dominated in the initial 5 min,while homogeneous oxidation reactions played more essential parts than others in the following reaction stage(5–60 min).Overall,this study demonstrated that the FeS-S_(2)O_(8)^(2-)process is capable of removing CBZ from water efficiently.
基金supported by Tai Shan Scholar Foundation (No.ts201511003)financial support from the Australian Research Council via Discovery Projects (Nos.DE210100253 and DP190103548)。
文摘Carbon-based single-atom catalysts(SACs) with atomic sizes of active sites have become the promising candidates for a variety of catalytic systems because of their high atom utilization, and unique electronic structures. Different types of single-atom sites can be fabricated via multiple preparation strategies, which would demonstrate distinct different coordination configurations and electronic features, and ultimately affected the structure-catalysis relationship of SACs in targeted reactions. As a result, it is necessary to identify the active sites of SACs and understand the structure-catalysis relationship of SACs at the atomic scale. In this review, a variety of preparation strategies of carbon-based SACs were documented. Then, the recent development on versatile characterization techniques and computational achievements were summarized regarding in understanding the electronic and geometric characteristics of carbon-based SACs.Finally, major challenges and development directions concerning single-atom sites identification and advanced tools development are discussed to shed light on future research of carbon-based SACs.
基金supported by the National Natural Science Foundation of China(No.21263006)the Science Research Foundation of Educational Commission of Yunnan Province of China(No.2012Y542)the Introduced Talents Foundation of Kunming University of Science and Technology
文摘3d transition metals doped CuGaS2 are considered as possible absorbing material candidates for intermediated band thin film solar cells. The electronic structure and optical properties of 3d transition metals doped CuGaS2 are investigated by using density functional theory calculations with the GGA + U method in the present work. The doping with 3d transition metals does not obviously change the crystal structure, band gap, and optical absorption edge of the CuGaS2 host. However, in the case of CuGa1-χTMχS2 (TM = Ti, V, Cr, Fe, and Ni), there is at least one distinct isolated impurity energy level in the band gap, and the optical absorption is enhanced in the ultraviolet-light region. Therefore, these materials are band thin film solar ceils. The calculated results are very well better explain them. ideal absorber material candidates for intermediated consistent with experimental observations, and could better explain them.
基金Project supported in part by Fundacao de AmparoàPesquisa do Estado de Sao Paulo-FAPESP(2013/07296-2,2016/23891-6,2017/26105-4,2019/01732-1)Financiadora de Estudos e Projetos-FINEP,Conselho Nacional de Desenvolvimento Científico e Tecnológico-CNPQ(166281/2017-4,305792/2020-2)CAPES。
文摘In this work,the impact of the doping process on the photoluminescence emission of CaWO_(4) as a function of the concentration of Eu^(3+) cation(0.01 mol%,0.02 mol%,0.04 mol%,0.06 mol%,0.08 mol%,and 0.10 mol%) is discussed in detail.Ca_(1-x)WO~4:xEu^(3+) samples were successfully synthesized by a simple coprecipitation method followed by microwave irradiation.The blue shift in the absorption edge confirms the quantum confinement effect and the band gap energy covers the range from 3.91 to 4.18 eV,as the amount of Eu^(3+) cations increases.The experimental results are sustained by first-principles calculations,at the density functional theory level,to decipher the geometry and electronic properties,thereby enabling a more accurate and direct comparison between theory and experiment for the Ca_(1-x)WO_(4):xEu^(3+) structure.
基金Financial supports from China Postdoctoral Science Foundation (Nos.2019M650007 and 2020M670088)National NaturalScience Foundation of China (Nos.21906001,51721006)the Beijing Nova Program (No. Z19111000110000)
文摘Acetaminophen(ACE)is commonly used in analgesic and antipyretic drug,which is hardly removed by traditional wastewater treatment processes.Herein,amorphous Co(OH)_(2)nanocages were explored as peroxymonosulfate(PMS)activator for efficient degradation of ACE.In the presence of amorphous Co(OH)_(2)nanocages,100%of ACE removal was reached within 2 min with a reaction rate constant k_(1)=3.68 min 1 at optimum pH 5,which was much better than that of crystallineβ-Co(OH)_(2)and Co_(3)O_(4).Amorphous materials(disorder atom arrangement)with hollow structures possess large specific surface area,more reactive sites,and abundant vacancies structures,which could efficiently facilitate the catalytic redox reactions.The radicals quenching experiment demonstrated that SO_(4)^(·-)radicals dominated the ACE degradation rather than^(·)OH radicals.The mechanism of ACE degradation was elucidated by the an alysis of degradation in termediates and theoretical calculation,indicating that the electrophilic SO_(4)^(·-)and^(·)OH tend to attack the atoms of ACE with high Fukui index(f).Our finding highlights the remarkable advantages of amorphous materials as heterogeneous catalysts in sulfate radicals-based AOPs and sheds new lights on water treatment for the degradation of emerging organic contaminants.
基金This project was supported by the National Key R&D Program of China(No.2016YFD0300708)。
文摘Four novel 2-methoxyimino phenylacetate derivatives containing 1,3,4-oxadiazole ring were designed and synthesized from the key intermediate of Trifloxystrobin or Azoxystrobin via intermediate derivatization and active structure splicing.The chemical structures of the target compounds were confirmed by]H NMR,13C NMR and elemental analysis.The crystal structure of methyl(E)-2-(methoxyimino)-2-(2-(((5-((4-methoxyphenoxy)methyl)-1,3,4-oxadiazol-2-yl)thio)methyl)phenyl)acetate(Al)was determined by single-crystal X-ray diffraction.Compound A1 belongs to triclinic system,space group Pi with two molecules in each unit cell.The benzene ring plane C(2)-C(3)-C(4)-C(5)-C(6)-C(7)and oxazole ring plane are nearly parallel with the dihedral angle of 6.4°.The benzene ring plane C(12)-C(13)-C(14)-C(15)-C(16)-C(17)and oxazole ring plane are not perpendicular with the dihedral angle of 49.4°.The crystal of compound Al is stabilized by π-π stacking interactions.The fungicidal activities of the target compounds against four plant pathogenic fungi in vitro were tested,and some of them had good activities.The DFT calculation was carried out to study the structure-activity relationship of the title derivatives using Gasian 09 and Multiwfii 3.6.
基金supported by the National Natural Science Foundation of China(No.21501037)the Natural Science Foundation of Hainan Province(No.20152017)the Science and Research Project of Education Department of Hainan Province(Nos.Hjkj2013-25 and Hnky2015-27)
文摘Two new fluorinated phenylisoquinoline-based iridium(Ⅲ) complexes,[Ir(f2piq)2(bipy)][PF6](3a) and[Ir(fmpiq)2(bipy)][PF6](3b)(f2piq = l-(2,4-difluorophenyl)isoquinoline,fmpiq = 1-(4-fluoro-2-methylphenyl)isoquinoline,bipy = 2,2'-bipyridine),have been synthesized and fully characterized.Single crystal X-ray diffraction study has been undertaken on complexes 3a and 3b,which show that each adopts the distorted octahedral coordination geometry with the cis-C,C' and trans-N,N' configuration.The photoluminescence spectra of 3a and 3b exhibit yellow and orange emission maxima at 584 and 600 nm,respectively.The frontier molecular orbital diagrams and the lowest-energy electronic transitions of 3a-3b have been calculated with density functional theory(DFT) and time-dependent DFT(TD-DFT).The absorption and emission spectra of complex 3b is red-shifted relative to those of complex 3a,as a consequence of the nature of the methyl group.
基金Financial support from the National Natural Science Foundation of China(Grant#s:21425207,21521002,21573233,and 21672216)the Chinese Academy of Sciences is greatly acknowledged.
文摘We have developed an N-heterocyclic carbene(NHC)-catalyzed domino reaction with aryl alde-hyde through a simple acyl azolium intermediate using phenyliodine(III)diacetate(PIDA)as an oxi-dant.Controlled experiments and density functional theory calculations supported a domino two-stage mechanism from aldehyde/amine to anα-oxygen-ation product,including NHC-catalyzed oxidation of the aldehyde to carboxylic acid via acyl azolium intermediate,and further,an addition of carboxyl-ate to iminium intermediate.Our study reveals a new model for the oxidation of Breslow intermedi-ate via electrophilic attack of the hydroxyl group by PIDA.
基金financially supported by the Natural Science Foundation of Hebei(Nos.F2020202027 and F2020202067)the Major National Science and Technology Special Projects(No.2016ZX02301003-004-007)+1 种基金the National Natural Science Foundation of China(No.21271139)the Natural Science Foundation of Tianjin(No.17JCTPJC54500)。
文摘P-xylene(p-C_(8)H_(10))is extremely harmful and dangerous to human health due to high toxicity and strong carcinogenicity.Exploring sensitive material to effectively detect p-xylene is of importance.In this paper,perovskite single crystal(C_(4)H_(9)NH_(3))_(2)PbI_(4) has been successfully synthesized via solution method.The obtained product was analyzed by single crystal X-ray diffraction.With the space group Pbca,orthorhombic(C_(4)H_(9)NH_(3))_(2)PbI_(4) layered perovskite structure consists of an extended two-dimensional network of corner-sharing PbI_(6) octahedron.Single layer perovskite sheets of distorted PbI_(6) octahedron alternated with protonated n-butylammonium cation bilayers,which offers many advantages and provides the possibility of forming a gas sensor device based on the change of resistances.Density functional theory(DFT)simulations regarding the adsorption energy revealed that this organicinorganic hybrid perovskite compound has excellent selectivity toward p-xylene compared with other gases including C_(2)H_(5)OH,C_(6)H_(6),CH_(2)Cl_(2),HCHO,CH_(3)COCH_(3) and C_(7)H_(8).The calculation of electron density,density of states and electron density difference showed the sensing mechanism of p-C_(8)H_(10) is mainly derived from physical adsorption-desorption in view of electron transfer.
文摘Two new 1,3-dithiole derivatives, 4,4'-{9-[4,5-bis(methylthio)-1,3-dithiol-2-ylidene]-9H-fluorene-2,7- diyl} dipyridine(2a) and 3,3'-{9-[4,5-bis(methylthio)-1,3-dithiol-2-ylidene]-9H-fluorene-2,7-diyl} dipyridine(2b) were synthesized and characterized by Fourier transform infrared(FTIR), 1H NMR, 13C NMR and mass spectroscopies. The crystal structure of compound 2b was also studied. The optimized conformations and molecular orbital diagrams of compounds 2a and 2b were illustrated via density functional theory(DFT). By the time-dependent DFT(TD-DFT) method, electronic absorption spectra of compounds 2a and 2b were predicted and the results achieved were in good agreement with the experimental data. The formation of the cationic radical during the electrochemical oxidation process was also proposed.
基金supported by the National Natural Science Foundation of China (51702039)。
文摘The sluggish kinetics of the electrochemical oxygen reduction reaction(ORR)in intermediatetemperature solid oxide fuel cells(IT-SOFCs)greatly limits the overall cell performance.In this study,an efficient and durable cathode material for IT-SOFCs is designed based on density functional theory(DFT)calculations by co-doping with Nb and Ta the B-site of the SrFeO_(3-δ)perovskite oxide.The DFT calculations suggest that Nb/Ta co-doping can regulate the energy band of the parent SrFeO_(3-δ)and help electron transfer.In symmetrical cells,such cathode with a SrFe_(0.8)Nb_(0.1)Ta_(0.1)O_(3-δ)(SFNT)detailed formula achieves a low cathode polarization resistance of 0.147Ωcm^(2) at 650℃.Electron spin resonance(ESR)and X-ray photoelectron spectroscopy(XPS)analysis confirm that the co-doping of Nb/Ta in SrFeO_(3-δ)B-site increases the balanced concentration of oxygen vacancies,enhancing the electrochemical performance when compared to 20 mol%Nb single-doped perovskite oxide.The cathode button cell with NiSDC|SDC|SFNT configuration achieves an outstanding peak power density of 1.3 W cm^(-2)at 650℃.Moreover,the button cell shows durability for 110 h under 0.65 V at 600℃ using wet H_(2) as fuel.
基金supported by the National Natural Science Foundation of China(22279025,21773048)the Natural Science Foundation of Heilongjiang Province(LH2021A013)+1 种基金the Sichuan Science and Technology Program(2021YFSY0022)the Fundamental Research Funds for the Central Universities(2023FRFK06005,HIT.NSRIF202204)。
文摘Developing efficient and stable cathodes for low-temperature solid oxide fuel cells(LT-SOFCs) is of great importance for the practical commercialization.Herein,we propose a series of Sm-modified Bi_(0.7-x)Sm_xSr_(0.3)FeO_(3-δ) perovskites as highly-active catalysts for LT-SOFCs.Sm doping can significantly enhance the electrocata lytic activity and chemical stability of cathode.At 600℃,Bi_(0.675)Sm_(0.025)Sr_(0.3)FeO_(3-δ)(BSSF25) cathode has been found to be the optimum composition with a polarization resistance of 0.098 Ω cm^2,which is only around 22.8% of Bi_(0.7)Sr_(0.3)FeO_(3-δ)(BSF).A full cell utilizing BSSF25 displays an exceptional output density of 790 mW cm^(-2),which can operate continuously over100 h without obvious degradation.The remarkable electrochemical performance observed can be attributed to the improved O_(2) transport kinetics,superior surface oxygen adsorption capacity,as well as O_(2)p band centers in close proximity to the Fermi level.Moreover,larger average bonding energy(ABE) and the presence of highly acidic Bi,Sm,and Fe ions restrict the adsorption of CO_(2) on the cathode surface,resulting in excellent CO_(2) resistivity.This work provides valuable guidance for systematic design of efficient and durable catalysts for LT-SOFCs.
基金supported by the National Natural Science Foundation of China(52374301 and 22279030)the Fundamental Research Funds for the Central Universities(N2223037)+1 种基金Hebei Key Laboratory of Dielectric and Electrolyte Functional Material,Northeastern University at Qinhuangdao(HKDEFM2021201)the Performance subsidy fund for the Key Laboratory of Dielectric and Electrolyte Functional Material Hebei Province(22567627H)。
文摘The interface mechanism between catalyst and carbon substrate has been the focus of research.In this paper,the FeCo alloy embedded N,S co-doped carbon substrate bifunctional catalyst(FeCo/S-NC)is obtained by a simple one-step pyrolysis strategy.The experimental results and density functional theory(DFT)calculation show that the formation of FeCo alloy is conducive to promoting electron transfer,and the introduction of S atom can enhance the interaction between FeCo alloy and carbon substrate,thus inhibiting the migration and agglomeration of particles on the surface of carbon material.The FeCo/SNC catalysts show outstanding performance for oxygen reduction reaction(ORR)and oxygen evolution reaction(OER).FeCo/S-NC shows a high half-wave potential(E_(1/2)=0.8823 V)for ORR and a low overpotential at 10 mA cm^(-2)(E_(j=10)=299 mV)for OER.In addition,compared with Pt/C+RuO_(2) assembled Zn-air battery(ZAB),the FeCo/S-NC assembled ZAB exhibits a larger power density(198.8 mW cm^(-2)),a higher specific capacity(786.1 mA h g_(zn)~(-1)),and ultra-stable cycle performance.These results confirm that the optimized composition and the interfacial interaction between catalyst and carbon substrate synergistically enhance the electrochemical performance.
基金supported by the National Natural Science Foundation of China(52274307)National Key Research and Development Program of China(2021YFC2901100)+1 种基金Science Foundation of China University of Petroleum,Beijing(2462022QZDX008,2462021QNX2010)State Key Laboratory of Heavy Oil Processing(HON-KFKT2022-10).
文摘The nickel-rich layered cathode material LiNi_(0.8)Co_(0.1)Mn_(0.1)O_(2)(NCM811)has high energy density,lower cost and is a promising cathode material currently under development.However,its electrochemical and structural stability is poor during cycling.Among the many modification methods,cation doping has been consistently proven to be an effective strategy for enhancing electrochemical performance.Herein,the NCM811 cathode material was modified by solid-phase reactions with Mg and Al doped.In addition,the corresponding mechanism of NCM811 cathode material-doped modification is explored by density functional theory(DFT)calculations,and we have extended this approach to other ternary cathode materials with different ratios and obtained universal laws.Combined with DFT calculations,the results show that Mg2+occupies the Li+site and reduces the degree of Li^(+)/Ni^(2+) mixture;Al^(3+) acts as a structural support during charging and discharging to prevent structural collapse.The electrochemical properties were tested by an electrochemical workstation and the LAND system,and the results showed that the capacity retention rate increased to varying degrees from 63.66%to 69.87%and 89.05%for NCM811-Mg and NCM811-Al at room temperature after 300 cycles,respectively.This study provides a theoretical basis and design strategy for commercializing cationic-doped modification of nickel-rich cathode materials.
基金supported by the Research Grants Council(26206115,16304821 and 16309418)the Southern Marine Science and Engineering Guangdong Laboratory(Guangzhou)(SMSEGL20SC01)+2 种基金the Innovation and Technology Commission(grant no.ITC-CNERC14EG03)of the Hong Kong Special Administrative Regionthe Hong Kong Postdoctoral Fellowship Scheme(HKUST PDFS2021-4S12 and HKUST PDFS2021-6S08)the support from the Shenzhen fundamental research funding(JCYJ20210324115809026,20200925154115001,JCYJ20200109141216566)。
文摘Urea generation through electrochemical CO_(2) and NO_(3)~-co-reduction reaction(CO_(2)NO_(3)RR)is still limited by either the low selectivity or yield rate of urea.Herein,we report copper carbonate hydroxide(Cu_2(OH)_2CO_(3))as an efficient CO_(2)NO_(3)RR electrocatalyst with an impressive urea Faradaic efficiency of45.2%±2.1%and a high yield rate of 1564.5±145.2μg h~(-1)mg_(cat)~(-1).More importantly,H_(2) evolution is fully inhibited on this electrocatalyst over a wide potential range between-0.3 and-0.8 V versus reversible hydrogen electrode.Our thermodynamic simulation reveals that the first C-N coupling follows a unique pathway on Cu_2(OH)_2CO_(3) by combining the two intermediates,~*COOH and~*NHO.This work demonstrates that high selectivity and yield rate of urea can be simultaneously achieved on simple Cu-based electrocatalysts in CO_(2)NO_(3)RR,and provide guidance for rational design of more advanced catalysts.
基金financially supported by the Open Fund of Energy and Materials Chemistry Joint Laboratory of SCNU and TINCI,China (SCNU-TINCI-202207)。
文摘Solving the problems of low electrical conductivity and poor cycling durability in transition metal oxidesbased anode materials for lithium-ion batteries(LIBs)and sodium-ion batteries(SIBs)has already turned into an urgent requirement.In this paper,we successfully synthesized Co_(2)VO_(4)/Co compounds with Co-VMOF(metal-organic framework)as a sacrificial template and investigated their electrochemical mechanism in order to improve the electrochemical properties of LIBs and SIBs.The optimized heaping configuration and the existence of metallic Co catalyzed the formation of radical ions,thereby facilitating higher conductivity,shortening Li+and Na+transport paths,and providing more active sites.Co_(2)VO_(4)/Co constructed with 2-methylimidazole as a ligand showed a discharge capacity of 1605.1 mA h g^(-1)after 300 cycles at 0.1 A g^(-1)in LIB and 677.2 mA h g^(-1)in SIB.Density functional theory(DFT)calculation emphasizes the crucial role of Co_(2)VO_(4)/Co in enhancing electrode conductivity,decreasing the migratory energy barrier,and thereby strengthening electrochemical properties.This heterostructure building technique may pave the way for the development of high-performance LIBs and SIBs.Furthermore,the problem of the low first-loop coulombic efficiency faced by transition metal oxides is improved.
基金the National Elite Foundationthe Institute for Advanced Studies in Basic Sciences for their financial supportfinancially supported by the National Natural Science Foundation of China(22173026,22350410386,22375200,U22A202175,21961142006)。
文摘This study investigates the effects of Fe on the oxygen-evolution reaction(OER)in the presence of Au.Two distinct areas of OER were identified:the first associated with Fe sites at low overpotential(~330 mV),and the second with Au sites at high overpotential(~870 mV).Various factors such as surface Fe concentration,electrochemical method,scan rate,potential range,concentration,method of adding K_(2)Fe O_(4),nature of Fe,and temperature were varied to observe diverse behaviors during OER for Fe O_(x)H_(y)/Au.Trace amounts of Fe ions had a significant impact on OER,reaching a saturation point where the activity did not increase further.Strong electronic interaction between Fe and Au ions was indicated by X-ray photoelectron spectroscopy(XPS)and electron paramagnetic resonance(EPR)analyses.In situ visible spectroscopy confirmed the formation of Fe O_(4)^(2-)during OER.In situ Mossbauer and surfaceenhanced Raman spectroscopy(SERS)analyses suggest the involvement of Fe-based species as intermediates during the rate-determining step of OER.A lattice OER mechanism based on Fe O_(x)H_(y)was proposed for operation at low overpotentials.Density functional theory(DFT)calculations revealed that Fe oxide,Fe-oxide clusters,and Fe doping on the Au foil exhibited different activities and stabilities during OER.The study provides insights into the interplay between Fe and Au in OER,advancing the understanding of OER mechanisms and offering implications for the design of efficient electrocatalytic systems.