The crystal and molecular structures of cydta (trans-1, 2-cyclohexanediaminetetraacetic acid) have been determined by single\|crystal X-ray structure analyses. The reasons that RE Ⅲ -edta and RE Ⅲ -cydta compl...The crystal and molecular structures of cydta (trans-1, 2-cyclohexanediaminetetraacetic acid) have been determined by single\|crystal X-ray structure analyses. The reasons that RE Ⅲ -edta and RE Ⅲ -cydta complexes select different coordinate structures were discussed and illustrated through the comparison of the molecular and crystal structures between edta and cydta, (NH_ 4 )\[Y Ⅲ (edta)(H_ 2 O)_ 3 \]\55H_ 2 O and (NH_ 4 )\[Y Ⅲ (cydta)(H_ 2 O)_ 2 \]\55H_ 2 O as well as (NH_ 4 )\[Gd Ⅲ (edta)(H_ 2 O)_ 3 \]\55H_ 2 O and (NH_ 4 )\[Gd Ⅲ (cydta) (H_ 2 O) _ 2 \]\55H_ 2 O complexes.展开更多
The title complex was synthesised and its molecular and crystal structures were determined by single crystal X ray reflection structure analysis. The crystal data are as follows: K[In Ⅲ(EDTA)(H 2O)]·2H 2O (...The title complex was synthesised and its molecular and crystal structures were determined by single crystal X ray reflection structure analysis. The crystal data are as follows: K[In Ⅲ(EDTA)(H 2O)]·2H 2O (EDTA=ethylene diamine N, N, N′, N′ tetraacetate), Monoclinic, C c space group, a=0.9096(2) nm,b=1.1996(2) nm, c =1.5144(3) nm, β =99.40(3)°, V =1.6302(6) 3, Z =3, D c=1.498 g·cm -3 , μ =1.325 mm -1 , F (000)=726, R =0.0320 and R W=0.0903 for 2315 observed independent reflections. The complex anion [In Ⅲ(EDTA)(H 2O)] - has a seven coordinate pseudo pentagonal bipyramidal (PB D 5h ) structure, in which the EDTA serves as a hexadentate ligand with two N atoms and four O atoms and one water molecule (H 2O) directly coordinated to the central metal ion In Ⅲ as a seventh ligand. 〓〓展开更多
Rare earth elements(REEs) are associated with phosphorite,which is an important strategic reserve resource.During sorting process of phosphorite,REEs may move with specific host minerals,however,occurrence state and m...Rare earth elements(REEs) are associated with phosphorite,which is an important strategic reserve resource.During sorting process of phosphorite,REEs may move with specific host minerals,however,occurrence state and moving pattern of REEs from rock to products are still unclear,which limits separation and enrichment of REEs from phosphorite.Mappings of scanning electron microscope(SEM) and electron probe X-ray micro-analyzer(EPMA) of REEs are highly consistent with those of calcium and phosphorus,and complementary with that of magnesium,which indicates that fluorapatite(Fap) is the main host mineral of REEs.The results of flotation and leaching experiments further indicate that REEs are enriched along with Fap from phosphorite to products.Occupied sites and occupation number of REEs were obtained by X-ray diffraction(XRD) refinement based on the Rietveld method.La,Ce,Nd,and Y can occupy both Ca1 and Ca2 sites.The ratios of La,Ce,Nd,and Y at Ca2 and Cal sites are 4.20,3.70,3.00,and 1.33,showing a decreasing trend,indicating that La,Ce,and Nd tend to occupy Ca2 sites,while Y tends to occupy Ca1 sites.X-ray absorption fine structure(XAFS) shows that REEs mainly form coordinate structures with oxygen and fluorine,which is a direct evidence that REEs replace calcium(Ⅱ) in phosphorite in an isomorphism form.Coordination structure and polyhedral configuration analysis indicate that substitution degree of La,Ce,Nd,and Y is Y> La> Ce≈Nd from easy to difficult at Cal and Ca2 sites.The research enriches the mineralization theory of REEs-bearing phosphorite and provides certain theoretical guidance for selective enrichment of REEs from phosphorite.展开更多
Single-atom catalysts(SACs)have garnered interest in designing their ligand environments,facilitating the modification of single catalytic sites toward high activity and selectivity.Despite various synthetic approache...Single-atom catalysts(SACs)have garnered interest in designing their ligand environments,facilitating the modification of single catalytic sites toward high activity and selectivity.Despite various synthetic approaches,it remains challenging to achieve a catalytically favorable coordination structure simultaneously with the feasible formation of SACs at low temperatures.Here,a new type of coordination structure for Pt SACs is introduced to offer a highly efficient hydrogen evolution reaction(HER)catalyst,where Pt SACs are readily fabricated by atomically confining PtCl_(2)on chemically driven NO_(2)sites in two-dimensional nitrogen-doped carbon nanosheets at room temperature.The resultant Pt SACs form the NO_(2)-Pt-Cl_(2)coordination structure with an atomic dispersion,as revealed by X-ray spectroscopy and transmission electron microscopy investigations.Moreover,our first-principles density functional theory(DFT)calculations show strong interactions in the coordination by computing the binding energy and charge density difference between PtCl_(2)and NO_(2).Pt SACs,established on the NO_(2)-functionalized carbon support,demonstrate the onset potential of 25 mV,Tafel slope of 40 mV dec^(-1),and high specific activity of 1.35 A mgPt^(-1).Importantly,the Pt SACs also exhibit long-term stability up to 110 h,which is a significant advance in the field of single-atom Pt catalysts.The newly developed coordination structure of Pt SACs features a single Pt active center,providing hydrogen binding ability comparable to that of Pt(111),enhanced long-term durability due to strong metal-support interactions,and the advantage of room-temperature fabrication.展开更多
Proton exchange membrane fuel cells have been identified as a potentially valuable technology for the efficient conversion of hydrogen energy into electrical energy.Nevertheless,one significant constraint on the perfo...Proton exchange membrane fuel cells have been identified as a potentially valuable technology for the efficient conversion of hydrogen energy into electrical energy.Nevertheless,one significant constraint on the performance of fuel cells is the oxygen reduction reaction(ORR).It is meaningful to progress the development of representative ORR electrocatalysts.In recent times,there has been an intensified focus on single-atom catalysts(SACs)due to the advantages of homogeneous distribution and high atom utilization efficiency.In particular,the coordination structure of metal sites plays an important role in the electrochemical performance of SACs.However,the relationship between coordination structures and catalytic performance remains unclear.In this review,we summarized the research progress on SACs in electrocatalytic ORR in recent years.Then the structure-activity relationship in the symmetric and asymmetric coordination structures of SACs was clarified.We further proposed rational design principles for regulating the coordination structure of SACs.Finally,the opportunities and challenges were discussed.展开更多
The development of efficient low-load platinum catalysts for CO oxidation is critical for large-scale industrial applications and environmental protection.In this study,a strategy of N_(2)treatment triggered the self-...The development of efficient low-load platinum catalysts for CO oxidation is critical for large-scale industrial applications and environmental protection.In this study,a strategy of N_(2)treatment triggered the self-reforming into fully exposed Pt cluster catalysts was proposed.By adjusting the coordination environment of Pt species on the defect support through N_(2)treatment,the CO catalytic activity was significantly enhanced,achieving complete CO oxidation at 130℃with a Pt loading of only 0.1 wt.%.The turnover frequency of N_(2)-treated Pt_(FEC)/Ti-D at 160℃was 18.3 times that of untreated Pt_(SA)/Ti-D.Comprehensive characterization results indicated that the N_(2)treatment of the Pt single-atom defect catalyst facilitated the reconfiguration and evolution of the defect structure,leading to the aggregation of Pt single atoms into fully exposed Pt clusters.Notably,these fully exposed Pt clusters exhibited a reduced coordination of Pt–O in the first coordination shell compared to single atoms,which resulted in the formation of Pt–Pt metal coordination.This unique coordination structure enhanced the adsorption and activation of CO and O_(2)on the catalyst,thereby resulting in exceptionally low-temperature CO oxidation activity.This work demonstrates a promising strategy for the design,synthesis,and industrial application of efficient low-platinum load catalysts.展开更多
Si coordination structures have been proven to greatly influence the ammonia-selective catalytic reduc-tion(NH_(3)-SCR)catalytic properties and the hydrothermal stability of Cu-based silicoaluminophosphate-form cataly...Si coordination structures have been proven to greatly influence the ammonia-selective catalytic reduc-tion(NH_(3)-SCR)catalytic properties and the hydrothermal stability of Cu-based silicoaluminophosphate-form catalysts.However,the role of various Si coordination structures in the NH_(3)-SCR reaction over Cu-SAPO-34 catalyst remains unknown.Herein,a batch of Cu-SAPO-34 samples with various Si contents was synthesized via a one-pot method to study the role of Si coordination structures in the NH_(3)-SCR catalytic properties and hydrothermal stability.Cu/34-2 with the highest proportion of Si(xOAl)(x=1~3)struc-tures exhibits remarkable durability with 90%NO reduction efficiency within 200~450℃ even after a hydrothermal aging treatment at 850℃.In contrast,Cu/34-1 and Cu/34-4 with the highest proportions of Si(4OAl)and Si(0OAl)structures,respectively,are significantly deactivated by the same hydrothermal treatment.To better understand this phenomenon,the relationship between the Si coordination struc-tures and SCR performance is established using characterization techniques and kinetics measurements.Results reveal that a high content of Si(4OAl)and Si(0OAl)is detrimental to the hydrothermal stability of Cu-SAPO-34 catalyst.However,Si(x OAl)(x=1~3)structures are conducive to the stabilization of isolated Cu^(2+),thus enhancing the stability to severe hydrothermal treatment.展开更多
Two new Ag~Ⅰ-complexes have been synthesized based on the semi-rigid ligand 2-（（pyridin-3-ylmethyl）thio）-5-（6-quinolinyl）-1,3,4-oxadiazole（L）,obtained by the condensation reaction of 5-（6-quinolinyl）-1,3,4-...Two new Ag~Ⅰ-complexes have been synthesized based on the semi-rigid ligand 2-（（pyridin-3-ylmethyl）thio）-5-（6-quinolinyl）-1,3,4-oxadiazole（L）,obtained by the condensation reaction of 5-（6-quinolinyl）-1,3,4-oxadiazole-2-thiol and 3-chloromethyl pyridine hydrochloride. Crystallization of L with Ag OTf and Ag PF_6 in a CH_2Cl_2/MeO H mixed solvent system at room temperature affords a novel supramolecular [Ag_2L_2（CF_3SO_3）_2]（I） and a coordination polymer [Ag L（PF_6）]_n（Ⅱ）,respectively. Two complexes were characterized by TGA,X-ray powder and single-crystal diffraction.展开更多
In order to perform a study on the structural modulation in the Cd（Ⅱ）-L architecture（HL =（E）-2-[2-（3-pyridyl）ethenyl]-8-hydroxyquinoline）, two different dicarboxylic acids, namely, 2-aminoterephthalic acid（H...In order to perform a study on the structural modulation in the Cd（Ⅱ）-L architecture（HL =（E）-2-[2-（3-pyridyl）ethenyl]-8-hydroxyquinoline）, two different dicarboxylic acids, namely, 2-aminoterephthalic acid（H_2ATA） and 4,4￠-biphenyldicarboxylic acid（H_2BPDC）, are employed as the secondary auxiliary ligands. Two new complexes [Cd_2L_2（ATA）]（1） and [Cd_2L_2（BPDC）·2MeO H· 4H_2O]（2） with distinct 3D frameworks were obtained. In complex 1, ligands ATA bridge the 1D Cd（Ⅱ）-L infinite chains into a 3D polymeric coordination network. Complex 2 is a 3D porous framework, in which adjacent 2D Cd（Ⅱ）-L coordination layers were linked together by the coor- dinated BPDC ligands. The variant structures of two complexes indicate that the skeleton of dicarboxylate anions plays a great role in the assembly of such different frameworks. In addition, the photoluminescent properties（fluorescent emission, lifetime, and quantum yield） of polymers 1 and 2 were also investigated in the solid state.展开更多
In-depth understanding of the electrolyte-dependent intercalation chemistry in batteries through direct operando/in situ characterizations is crucial for the development of the high-performance batteries.Herein,taking...In-depth understanding of the electrolyte-dependent intercalation chemistry in batteries through direct operando/in situ characterizations is crucial for the development of the high-performance batteries.Herein,taking the Al/graphite battery as a model system,the effect of electrolyte coordination structure on the intercalation processes has been investigated over the batteries with either 1-hexyl-3-methylimidazolium chloride(HMICl)-AlCl_(3) or 1-ethyl-3-methylimidazolium chloride(EMICl)-AlCl_(3) ionic liquid electrolyte using operando X-ray photoelectron spectroscopy(XPS)and X-ray diffraction.With a weaker anion-cation interaction in HMI-based electrolyte,the XPS-derived atomic ratio between cointercalated N and intercalated Al is 0.9,which is lower than 1.6 for EMI-based electrolyte.Attributed to the additional de-solvation process,the batteries with the HMI-based electrolyte show a lower ionic diffusion rate,capacity,and cycling performance,which agree with the operando characterization results.Our findings highlight the critical role of the electrolyte coordination structure on the(co-)intercalation chemistry.展开更多
Fifteen M(S2COR)n complexes were prepared.According to the data provided by IR,UV-Vis absorption spectrometry and X-ray diffraction,this paper covers the relationship between molecular structures of xanthate complexes...Fifteen M(S2COR)n complexes were prepared.According to the data provided by IR,UV-Vis absorption spectrometry and X-ray diffraction,this paper covers the relationship between molecular structures of xanthate complexes and their absorption spectra and a criterion of chelate stability is also proposed.The stability mechanism of xanthate chelates and related rules were investigated.展开更多
The coordination compounds,{Cu[CH_3C_6H_4N(CH_2COO)_2]}.2H_2O and {Cu[CH_3OC_6H_4N(CH_2COO)_2]}.2H_2O,have been prepared and its crystal struc- tures determined.The final discrepancy factors are R=0.052,R_w=0.061 for ...The coordination compounds,{Cu[CH_3C_6H_4N(CH_2COO)_2]}.2H_2O and {Cu[CH_3OC_6H_4N(CH_2COO)_2]}.2H_2O,have been prepared and its crystal struc- tures determined.The final discrepancy factors are R=0.052,R_w=0.061 for (I)and R=0.052,R_w=0.039 for(Ⅱ).The geometry of the coordination poly- hedron with Cu(Ⅱ)is a distorted tetragonal pyramid for(Ⅰ)and an unsym- metrical and extended tetragonal bipyramid for(Ⅱ),respectively.The re- sults of EHMO calculations indicate that the ligand mainly provided the field with very few of its electrons being coordinated to the central atom.展开更多
A novel tetrazylphosphonate ligand, namely ethyl 4-（2-ethyl-2H-1,2,3,4-tetrazol-5-yl） benzylphosphonate（Et-L）, was designed and successfully achieved from p-cyano benzyl chloride, based on which a zinc coordinatio...A novel tetrazylphosphonate ligand, namely ethyl 4-（2-ethyl-2H-1,2,3,4-tetrazol-5-yl） benzylphosphonate（Et-L）, was designed and successfully achieved from p-cyano benzyl chloride, based on which a zinc coordination polymer（1） with a 2D layer structure has been hydrothermally synthesized and structurally characterized by elemental analysis, IR, TGA and X-ray single-crystal diffraction. The colorless block crystals of H_2L·H_2O were also obtained under the same hydrothermal conditions, which belongs to monoclinic system, space group P2_1/c with a = 13.3141（7）, b = 5.1650（3）, c = 21.9839（18） A, β = 115.307（5）°, V = 1366.69（15）A3, Z = 4, D_c = 1.391 mg/cm^（-3）, Mr = 349.58, F（000） = 600, R = 0.0748 and wR = 0.1917 for 2392 observed reflections（I 〉 2σ（I））. The colorless block crystals of complex 1（[Zn（L）（H_2O）]_n） also belong to monoclinic system, space group P2_1/c with a = 22.7464（10）, b = 6.0430（3）, c = 9.7704（4） ？, β = 92.525（4）°, V = 1341.70（10）A3, Z = 4, D_c = 1.731 mg/cm_（-3）, M_r = 349.58, F（000） = 712, R = 0.0596 and wR = 0.1688 for 2357 observed reflections（I 〉 2σ（I））. Only the oxygen atoms of phosphonic group are coordinated with the metal zinc probably because the hydrogen atom of tetrazole has been substituted by ethyl group. Photoluminescence properties of the complex are also investigated.展开更多
Two new Zn~Ⅱ coordination polymers,namely,[Zn L（o-bdc）]n（1） and [Zn L（mbdc）]_n·n H_2O（2）（L = 4？-（3-pyridyl）-3,2？：6？,3？？-terpyridine,H_2（o-bdc） = benzene-1,2-dicarboxylic acid,H_2（m-bdc） = be...Two new Zn~Ⅱ coordination polymers,namely,[Zn L（o-bdc）]n（1） and [Zn L（mbdc）]_n·n H_2O（2）（L = 4？-（3-pyridyl）-3,2？：6？,3？？-terpyridine,H_2（o-bdc） = benzene-1,2-dicarboxylic acid,H_2（m-bdc） = benzene-1,3-dicarboxylic acid）,were synthesized by hydrothermal methods. The crystal structures have been determined by single-crystal X-ray diffraction. Compound 1 crystallizes in monoclinic C2/c space group,with a = 28.016（2）,b = 11.3815（11）,c = 19.8071（17） ？,β = 133.961（2）°,V = 4546.2（7） ？3,Z = 8,Mr = 539.83,Dc = 1.577 Mg/m^3,μ = 1.127 mm-1,F（000） = 2208,the final R = 0.0426 and w R = 0.0986 for 2875 observed reflections with I 〉 2σ（I） and displays a 1D coordination chain. While compound 2 crystallizes in monoclinic C2/c space group,with a = 15.6003（14）,b = 11.9152（11）,c = 26.633（3） ？,β = 94.320（2）°,V = 4936.5（8） ？~3,Z = 4,M_r = 1115.67,Dc = 1.496 Mg/m^3,μ = 1.043 mm^（-1）,F（000） = 2272,the final R = 0.0499 and w R = 0.1342 for 2659 observed reflections with I 〉 2σ（I） and shows a classical 3D cds topological network with point symbol of {65.8}. Furthermore,thermal stability and luminescent properties of 1 and 2 have also been investigated.展开更多
Two new coordination polymers containing rigid bis（triazole）, namely, [Ni（btb）_（0.5）（nph）（H_2O）]_n（1） and [Zn（btb）（SO_4）]_n（2）（btb = 4,4a-bis（1,2,4-triazolyl-1-yl）-biphenyl, H_2nph = 3-nitrophthal...Two new coordination polymers containing rigid bis（triazole）, namely, [Ni（btb）_（0.5）（nph）（H_2O）]_n（1） and [Zn（btb）（SO_4）]_n（2）（btb = 4,4a-bis（1,2,4-triazolyl-1-yl）-biphenyl, H_2nph = 3-nitrophthalic acid） have been synthesized and characterized by elemental analysis, IR spectra, and single-crystal X-ray diffraction. Complex 1 shows a 3D trinodal（3,4,4）-connected sqc69 topology. Complex 2 presents a 2D uninodal 4-connected sql network, which is further packed into a 3D supramolecular framework by C-H···O hydrogen bonds. Thermal stabilities and fluorescence properties of two complexes have been discussed in detail.展开更多
Hydrothermal reactions of 3-cyanopyridine and Na N3 with Zn Cl_2 or Cd Cl_2·5/2H_2 O in the presence of 1,4-benzenedicarboxylic acid（H2bdc） yielded two new coordination polymers,{[Zn（3-ptz）（bdc）_（0.5）（H...Hydrothermal reactions of 3-cyanopyridine and Na N3 with Zn Cl_2 or Cd Cl_2·5/2H_2 O in the presence of 1,4-benzenedicarboxylic acid（H2bdc） yielded two new coordination polymers,{[Zn（3-ptz）（bdc）_（0.5）（H_2O）_2]n·2H_2O}_n（1） and [Cd_2（3-ptz）_2Cl_2]_n（2）,based on in situ synthesized 5-（3-pyridyl）tetrazolate（3-ptz-） organic ligand.They have been structurally characterized by elemental analysis（EA）,infrared spectroscopy（IR） and single-crystal/powder X-ray diffraction（PXRD）.In 1,two Zn（Ⅱ） ions are linked together through two μ_2-（3-ptz-） ligands to form a dimeric unit of [Zn（μ_2-3-ptz）（H_2O）_2]2^2＋,which is further connected with other equivalent units by μ_2-bdc^2-spacers,resulting in an infinite 1D polymeric chain of [Zn_2（3-ptz）_2（H_2O）_2（bdc）]_n,and then strong hydrogen bonding interactions extend these 1D chains into a 3D supramolecular structure.In 2,the Cd（Ⅱ） ions are connected through μ_4-（3-ptz-） ligands and Cl-anions,leading to infinite 2D layers of [Cd_2（3-ptz）Cl_2]_n^n＋,which are further linked by another μ_4-（3-ptz-） pillared ligand to form a 3D layered-pillared framework architecture of [Cd）2（3-ptz））2Cl）2]）n.Furthermore,thermal stability of these compounds was measured by thermogravimetric analysis（TGA） and their photoluminescent properties were also investigated in the solid state at room temperature.展开更多
Single-atom materials have demonstrated attractive physicochemical characteristics.However,understanding the relationships between the coordination environment of single atoms and their properties at the atomic level ...Single-atom materials have demonstrated attractive physicochemical characteristics.However,understanding the relationships between the coordination environment of single atoms and their properties at the atomic level remains a considerable challenge.Herein,a facile waterassisted carbonization approach is developed to fabricate well-defined asymmetrically coordinated Co–N_(4)–O sites on biomass-derived carbon nanofiber(Co–N_(4)–O/NCF)for electromagnetic wave(EMW)absorption.In such nanofiber,one atomically dispersed Co site is coordinated with four N atoms in the graphene basal plane and one oxygen atom in the axial direction.In-depth experimental and theoretical studies reveal that the axial Co–O coordination breaks the charge distribution symmetry in the planar porphyrin-like Co–N_(4) structure,leading to significantly enhanced dielectric polarization loss relevant to the planar Co–N_(4) sites.Importantly,the film based on Co–N_(4)–O/NCF exhibits light weight,flexibility,excellent mechanical properties,great thermal insulating feature,and excellent EMW absorption with a reflection loss of−45.82 dB along with an effective absorption bandwidth of 4.8 GHz.The findings of this work offer insight into the relationships between the single-atom coordination environment and the dielectric performance,and the proposed strategy can be extended toward the engineering of asymmetrically coordinated single atoms for various applications.展开更多
Density functional theory is used to investigate the complexes structures and properties of poly(vinyl ethylene carbonate)(PVEC/LiTFSI)and poly(vinylene carbonate)(PVCA/LiDFOB)electrolytes containing five-membered rin...Density functional theory is used to investigate the complexes structures and properties of poly(vinyl ethylene carbonate)(PVEC/LiTFSI)and poly(vinylene carbonate)(PVCA/LiDFOB)electrolytes containing five-membered ring carbonate groups under the polymer/Li^(+)model and the polymer/lithium salt model.In addition,the calculated and experimental values of the oxidation potentials of the two electrolytes were compared,and the reasons for the differences in the oxidation potentials of the two electrolytes are elucidated.The calculation results show that the PVEC/LiTFSI has more free ion structures and diverse coordination structures compared to PVCA/LiDFOB electrolyte.This provides a reasonable theoretical explanation for its higher ionic conductivity and lower cation mobility number.The PVEC/LiTFSI electrolyte has a lower oxidation potential compared to the PVCA/LiDFOB electrolyte,which is attributed to the proton transfer that occurs during its oxidation.展开更多
Photocatalytic decomposition of sugars is a promising way of providing H_(2),CO,and HCOOH as sus-tainable energy vectors.However,the production of C_(1) chemicals requires the cleavage of robust C−C bonds in sugars wi...Photocatalytic decomposition of sugars is a promising way of providing H_(2),CO,and HCOOH as sus-tainable energy vectors.However,the production of C_(1) chemicals requires the cleavage of robust C−C bonds in sugars with concurrent production of H_(2),which remains challenging.Here,the photo-catalytic activity for glucose decomposition to HCOOH,CO(C_(1) chemicals),and H_(2) on Cu/TiO_(2)was enhanced by nitrogen doping.Owing to nitrogen doping,atomically dispersed and stable Cu sites resistant to light irradiation are formed on Cu/TiO_(2).The electronic interaction between Cu and nitrogen ions originates valence band structure and defect levels composed of N 2p orbit,distinct from undoped Cu/TiO_(2).Therefore,the lifetime of charge carriers is prolonged,resulting in the pro-duction of C_(1) chemicals and H_(2) with productivities 1.7 and 2.1 folds that of Cu/TiO_(2).This work pro-vides a strategy to design coordinatively stable Cu ions for photocatalytic biomass conversion.展开更多
The Fe-N-C material represents an attractive oxygen reduction reaction electrocatalyst,and the FeN_(4)moiety has been identified as a very competitive catalytic active site.Fine tuning of the coordination structure of...The Fe-N-C material represents an attractive oxygen reduction reaction electrocatalyst,and the FeN_(4)moiety has been identified as a very competitive catalytic active site.Fine tuning of the coordination structure of FeN_(4)has an essential impact on the catalytic performance.Herein,we construct a sulfur-modified Fe-N-C catalyst with controllable local coordination environment,where the Fe is coordinated with four in-plane N and an axial external S.The external S atom affects not only the electron distribution but also the spin state of Fe in the FeN_(4)active site.The appearance of higher valence states and spin states for Fe demonstrates the increase in unpaired electrons.With the above characteristics,the adsorption and desorption of the reactants at FeN_(4)active sites are optimized,thus promoting the oxygen reduction reaction activity.This work explores the key point in electronic configuration and coordination environment tuning of FeN_(4)through S doping and provides new insight into the construction of M-N-C-based oxygen reduction reaction catalysts.展开更多
文摘The crystal and molecular structures of cydta (trans-1, 2-cyclohexanediaminetetraacetic acid) have been determined by single\|crystal X-ray structure analyses. The reasons that RE Ⅲ -edta and RE Ⅲ -cydta complexes select different coordinate structures were discussed and illustrated through the comparison of the molecular and crystal structures between edta and cydta, (NH_ 4 )\[Y Ⅲ (edta)(H_ 2 O)_ 3 \]\55H_ 2 O and (NH_ 4 )\[Y Ⅲ (cydta)(H_ 2 O)_ 2 \]\55H_ 2 O as well as (NH_ 4 )\[Gd Ⅲ (edta)(H_ 2 O)_ 3 \]\55H_ 2 O and (NH_ 4 )\[Gd Ⅲ (cydta) (H_ 2 O) _ 2 \]\55H_ 2 O complexes.
文摘The title complex was synthesised and its molecular and crystal structures were determined by single crystal X ray reflection structure analysis. The crystal data are as follows: K[In Ⅲ(EDTA)(H 2O)]·2H 2O (EDTA=ethylene diamine N, N, N′, N′ tetraacetate), Monoclinic, C c space group, a=0.9096(2) nm,b=1.1996(2) nm, c =1.5144(3) nm, β =99.40(3)°, V =1.6302(6) 3, Z =3, D c=1.498 g·cm -3 , μ =1.325 mm -1 , F (000)=726, R =0.0320 and R W=0.0903 for 2315 observed independent reflections. The complex anion [In Ⅲ(EDTA)(H 2O)] - has a seven coordinate pseudo pentagonal bipyramidal (PB D 5h ) structure, in which the EDTA serves as a hexadentate ligand with two N atoms and four O atoms and one water molecule (H 2O) directly coordinated to the central metal ion In Ⅲ as a seventh ligand. 〓〓
基金Project supported by Guizhou Provincial Basic Research Program (Natural Science)(Qian Ke He Basic-ZK 2024 General 626)National Natural Science Foundation of China (52164018)Scientific Research Foundation for High-level Talents of Anhui University of Science and Technology (13210025)。
文摘Rare earth elements(REEs) are associated with phosphorite,which is an important strategic reserve resource.During sorting process of phosphorite,REEs may move with specific host minerals,however,occurrence state and moving pattern of REEs from rock to products are still unclear,which limits separation and enrichment of REEs from phosphorite.Mappings of scanning electron microscope(SEM) and electron probe X-ray micro-analyzer(EPMA) of REEs are highly consistent with those of calcium and phosphorus,and complementary with that of magnesium,which indicates that fluorapatite(Fap) is the main host mineral of REEs.The results of flotation and leaching experiments further indicate that REEs are enriched along with Fap from phosphorite to products.Occupied sites and occupation number of REEs were obtained by X-ray diffraction(XRD) refinement based on the Rietveld method.La,Ce,Nd,and Y can occupy both Ca1 and Ca2 sites.The ratios of La,Ce,Nd,and Y at Ca2 and Cal sites are 4.20,3.70,3.00,and 1.33,showing a decreasing trend,indicating that La,Ce,and Nd tend to occupy Ca2 sites,while Y tends to occupy Ca1 sites.X-ray absorption fine structure(XAFS) shows that REEs mainly form coordinate structures with oxygen and fluorine,which is a direct evidence that REEs replace calcium(Ⅱ) in phosphorite in an isomorphism form.Coordination structure and polyhedral configuration analysis indicate that substitution degree of La,Ce,Nd,and Y is Y> La> Ce≈Nd from easy to difficult at Cal and Ca2 sites.The research enriches the mineralization theory of REEs-bearing phosphorite and provides certain theoretical guidance for selective enrichment of REEs from phosphorite.
基金supported by the National Research Foundation of Korea(NRF)(NRF-2020M3H4A3106354,NRF-2021M3I3A1083946,and NRF-2021R1A6A3A01087461)the Korea Institute of Science and Technology,and the KISTI Supercomputing Center(KSC-2023-CRE-0492).
文摘Single-atom catalysts(SACs)have garnered interest in designing their ligand environments,facilitating the modification of single catalytic sites toward high activity and selectivity.Despite various synthetic approaches,it remains challenging to achieve a catalytically favorable coordination structure simultaneously with the feasible formation of SACs at low temperatures.Here,a new type of coordination structure for Pt SACs is introduced to offer a highly efficient hydrogen evolution reaction(HER)catalyst,where Pt SACs are readily fabricated by atomically confining PtCl_(2)on chemically driven NO_(2)sites in two-dimensional nitrogen-doped carbon nanosheets at room temperature.The resultant Pt SACs form the NO_(2)-Pt-Cl_(2)coordination structure with an atomic dispersion,as revealed by X-ray spectroscopy and transmission electron microscopy investigations.Moreover,our first-principles density functional theory(DFT)calculations show strong interactions in the coordination by computing the binding energy and charge density difference between PtCl_(2)and NO_(2).Pt SACs,established on the NO_(2)-functionalized carbon support,demonstrate the onset potential of 25 mV,Tafel slope of 40 mV dec^(-1),and high specific activity of 1.35 A mgPt^(-1).Importantly,the Pt SACs also exhibit long-term stability up to 110 h,which is a significant advance in the field of single-atom Pt catalysts.The newly developed coordination structure of Pt SACs features a single Pt active center,providing hydrogen binding ability comparable to that of Pt(111),enhanced long-term durability due to strong metal-support interactions,and the advantage of room-temperature fabrication.
基金supported the National Natural Science Foundation of China(Nos.22108306 and 22478432)Taishan Scholars Program of Shandong Province(No.tsqn201909065)the Natural Science Foundation of Shandong Province(Nos.ZR2024JQ004 and ZR2021YQ15).
文摘Proton exchange membrane fuel cells have been identified as a potentially valuable technology for the efficient conversion of hydrogen energy into electrical energy.Nevertheless,one significant constraint on the performance of fuel cells is the oxygen reduction reaction(ORR).It is meaningful to progress the development of representative ORR electrocatalysts.In recent times,there has been an intensified focus on single-atom catalysts(SACs)due to the advantages of homogeneous distribution and high atom utilization efficiency.In particular,the coordination structure of metal sites plays an important role in the electrochemical performance of SACs.However,the relationship between coordination structures and catalytic performance remains unclear.In this review,we summarized the research progress on SACs in electrocatalytic ORR in recent years.Then the structure-activity relationship in the symmetric and asymmetric coordination structures of SACs was clarified.We further proposed rational design principles for regulating the coordination structure of SACs.Finally,the opportunities and challenges were discussed.
基金supported by the National Natural Science Foundation of China(52170118,52322004,52230002)the China Postdoctoral Science Foundation(2024M763296).
文摘The development of efficient low-load platinum catalysts for CO oxidation is critical for large-scale industrial applications and environmental protection.In this study,a strategy of N_(2)treatment triggered the self-reforming into fully exposed Pt cluster catalysts was proposed.By adjusting the coordination environment of Pt species on the defect support through N_(2)treatment,the CO catalytic activity was significantly enhanced,achieving complete CO oxidation at 130℃with a Pt loading of only 0.1 wt.%.The turnover frequency of N_(2)-treated Pt_(FEC)/Ti-D at 160℃was 18.3 times that of untreated Pt_(SA)/Ti-D.Comprehensive characterization results indicated that the N_(2)treatment of the Pt single-atom defect catalyst facilitated the reconfiguration and evolution of the defect structure,leading to the aggregation of Pt single atoms into fully exposed Pt clusters.Notably,these fully exposed Pt clusters exhibited a reduced coordination of Pt–O in the first coordination shell compared to single atoms,which resulted in the formation of Pt–Pt metal coordination.This unique coordination structure enhanced the adsorption and activation of CO and O_(2)on the catalyst,thereby resulting in exceptionally low-temperature CO oxidation activity.This work demonstrates a promising strategy for the design,synthesis,and industrial application of efficient low-platinum load catalysts.
基金financial support from the National Natural Science Foundation of China (No.52000084)the China Postdoctoral Science Foundation (No.2019M662630)。
文摘Si coordination structures have been proven to greatly influence the ammonia-selective catalytic reduc-tion(NH_(3)-SCR)catalytic properties and the hydrothermal stability of Cu-based silicoaluminophosphate-form catalysts.However,the role of various Si coordination structures in the NH_(3)-SCR reaction over Cu-SAPO-34 catalyst remains unknown.Herein,a batch of Cu-SAPO-34 samples with various Si contents was synthesized via a one-pot method to study the role of Si coordination structures in the NH_(3)-SCR catalytic properties and hydrothermal stability.Cu/34-2 with the highest proportion of Si(xOAl)(x=1~3)struc-tures exhibits remarkable durability with 90%NO reduction efficiency within 200~450℃ even after a hydrothermal aging treatment at 850℃.In contrast,Cu/34-1 and Cu/34-4 with the highest proportions of Si(4OAl)and Si(0OAl)structures,respectively,are significantly deactivated by the same hydrothermal treatment.To better understand this phenomenon,the relationship between the Si coordination struc-tures and SCR performance is established using characterization techniques and kinetics measurements.Results reveal that a high content of Si(4OAl)and Si(0OAl)is detrimental to the hydrothermal stability of Cu-SAPO-34 catalyst.However,Si(x OAl)(x=1~3)structures are conducive to the stabilization of isolated Cu^(2+),thus enhancing the stability to severe hydrothermal treatment.
基金financially supported by the National Natural Science Foundation of China(No.21201112)
文摘Two new Ag~Ⅰ-complexes have been synthesized based on the semi-rigid ligand 2-（（pyridin-3-ylmethyl）thio）-5-（6-quinolinyl）-1,3,4-oxadiazole（L）,obtained by the condensation reaction of 5-（6-quinolinyl）-1,3,4-oxadiazole-2-thiol and 3-chloromethyl pyridine hydrochloride. Crystallization of L with Ag OTf and Ag PF_6 in a CH_2Cl_2/MeO H mixed solvent system at room temperature affords a novel supramolecular [Ag_2L_2（CF_3SO_3）_2]（I） and a coordination polymer [Ag L（PF_6）]_n（Ⅱ）,respectively. Two complexes were characterized by TGA,X-ray powder and single-crystal diffraction.
基金supported by the National Natural Science Foundation of China(No.21201002)the Foundation of State Key Laboratory of Structural Chemistry(20130016)+1 种基金Anhui Provincial Natural Science Foundation(1308085QB22)Training Programs of Innovation and Entrepreneurship for Undergraduates(201410360023 and 201410360157)
文摘In order to perform a study on the structural modulation in the Cd（Ⅱ）-L architecture（HL =（E）-2-[2-（3-pyridyl）ethenyl]-8-hydroxyquinoline）, two different dicarboxylic acids, namely, 2-aminoterephthalic acid（H_2ATA） and 4,4￠-biphenyldicarboxylic acid（H_2BPDC）, are employed as the secondary auxiliary ligands. Two new complexes [Cd_2L_2（ATA）]（1） and [Cd_2L_2（BPDC）·2MeO H· 4H_2O]（2） with distinct 3D frameworks were obtained. In complex 1, ligands ATA bridge the 1D Cd（Ⅱ）-L infinite chains into a 3D polymeric coordination network. Complex 2 is a 3D porous framework, in which adjacent 2D Cd（Ⅱ）-L coordination layers were linked together by the coor- dinated BPDC ligands. The variant structures of two complexes indicate that the skeleton of dicarboxylate anions plays a great role in the assembly of such different frameworks. In addition, the photoluminescent properties（fluorescent emission, lifetime, and quantum yield） of polymers 1 and 2 were also investigated in the solid state.
基金financially supported by the National Key R&D Program of China (2021YFA1502800)the National Natural Science Foundation of China (21825203,22288201,and 91945302)+1 种基金the Photon Science Center for Carbon Neutrality,Liao Ning Revitalization Talents Program (XLYC1902117)the Youth Innovation Fund of Dalian institute of Chemical Physics (DICP I202125)。
文摘In-depth understanding of the electrolyte-dependent intercalation chemistry in batteries through direct operando/in situ characterizations is crucial for the development of the high-performance batteries.Herein,taking the Al/graphite battery as a model system,the effect of electrolyte coordination structure on the intercalation processes has been investigated over the batteries with either 1-hexyl-3-methylimidazolium chloride(HMICl)-AlCl_(3) or 1-ethyl-3-methylimidazolium chloride(EMICl)-AlCl_(3) ionic liquid electrolyte using operando X-ray photoelectron spectroscopy(XPS)and X-ray diffraction.With a weaker anion-cation interaction in HMI-based electrolyte,the XPS-derived atomic ratio between cointercalated N and intercalated Al is 0.9,which is lower than 1.6 for EMI-based electrolyte.Attributed to the additional de-solvation process,the batteries with the HMI-based electrolyte show a lower ionic diffusion rate,capacity,and cycling performance,which agree with the operando characterization results.Our findings highlight the critical role of the electrolyte coordination structure on the(co-)intercalation chemistry.
文摘Fifteen M(S2COR)n complexes were prepared.According to the data provided by IR,UV-Vis absorption spectrometry and X-ray diffraction,this paper covers the relationship between molecular structures of xanthate complexes and their absorption spectra and a criterion of chelate stability is also proposed.The stability mechanism of xanthate chelates and related rules were investigated.
基金Subject supported by the Doctoral Foundation of National Education Commission of China
文摘The coordination compounds,{Cu[CH_3C_6H_4N(CH_2COO)_2]}.2H_2O and {Cu[CH_3OC_6H_4N(CH_2COO)_2]}.2H_2O,have been prepared and its crystal struc- tures determined.The final discrepancy factors are R=0.052,R_w=0.061 for (I)and R=0.052,R_w=0.039 for(Ⅱ).The geometry of the coordination poly- hedron with Cu(Ⅱ)is a distorted tetragonal pyramid for(Ⅰ)and an unsym- metrical and extended tetragonal bipyramid for(Ⅱ),respectively.The re- sults of EHMO calculations indicate that the ligand mainly provided the field with very few of its electrons being coordinated to the central atom.
基金Support by National Natural Science Foundation of China(21371052)the Scientific Research Fund of Heilongjiang Provincial Education Department(12531512)
文摘A novel tetrazylphosphonate ligand, namely ethyl 4-（2-ethyl-2H-1,2,3,4-tetrazol-5-yl） benzylphosphonate（Et-L）, was designed and successfully achieved from p-cyano benzyl chloride, based on which a zinc coordination polymer（1） with a 2D layer structure has been hydrothermally synthesized and structurally characterized by elemental analysis, IR, TGA and X-ray single-crystal diffraction. The colorless block crystals of H_2L·H_2O were also obtained under the same hydrothermal conditions, which belongs to monoclinic system, space group P2_1/c with a = 13.3141（7）, b = 5.1650（3）, c = 21.9839（18） A, β = 115.307（5）°, V = 1366.69（15）A3, Z = 4, D_c = 1.391 mg/cm^（-3）, Mr = 349.58, F（000） = 600, R = 0.0748 and wR = 0.1917 for 2392 observed reflections（I 〉 2σ（I））. The colorless block crystals of complex 1（[Zn（L）（H_2O）]_n） also belong to monoclinic system, space group P2_1/c with a = 22.7464（10）, b = 6.0430（3）, c = 9.7704（4） ？, β = 92.525（4）°, V = 1341.70（10）A3, Z = 4, D_c = 1.731 mg/cm_（-3）, M_r = 349.58, F（000） = 712, R = 0.0596 and wR = 0.1688 for 2357 observed reflections（I 〉 2σ（I））. Only the oxygen atoms of phosphonic group are coordinated with the metal zinc probably because the hydrogen atom of tetrazole has been substituted by ethyl group. Photoluminescence properties of the complex are also investigated.
基金supported by the National Natural Science Foundation of China(Nos.21173164 and 21473133)
文摘Two new Zn~Ⅱ coordination polymers,namely,[Zn L（o-bdc）]n（1） and [Zn L（mbdc）]_n·n H_2O（2）（L = 4？-（3-pyridyl）-3,2？：6？,3？？-terpyridine,H_2（o-bdc） = benzene-1,2-dicarboxylic acid,H_2（m-bdc） = benzene-1,3-dicarboxylic acid）,were synthesized by hydrothermal methods. The crystal structures have been determined by single-crystal X-ray diffraction. Compound 1 crystallizes in monoclinic C2/c space group,with a = 28.016（2）,b = 11.3815（11）,c = 19.8071（17） ？,β = 133.961（2）°,V = 4546.2（7） ？3,Z = 8,Mr = 539.83,Dc = 1.577 Mg/m^3,μ = 1.127 mm-1,F（000） = 2208,the final R = 0.0426 and w R = 0.0986 for 2875 observed reflections with I 〉 2σ（I） and displays a 1D coordination chain. While compound 2 crystallizes in monoclinic C2/c space group,with a = 15.6003（14）,b = 11.9152（11）,c = 26.633（3） ？,β = 94.320（2）°,V = 4936.5（8） ？~3,Z = 4,M_r = 1115.67,Dc = 1.496 Mg/m^3,μ = 1.043 mm^（-1）,F（000） = 2272,the final R = 0.0499 and w R = 0.1342 for 2659 observed reflections with I 〉 2σ（I） and shows a classical 3D cds topological network with point symbol of {65.8}. Furthermore,thermal stability and luminescent properties of 1 and 2 have also been investigated.
基金supported by the National Natural Science Foundation of China(No.51474086)Natural Science Foundation-Steel and Iron Foundation of Hebei Province(B2015209299)the Graduate Student Innovation Fund of North China University of Science and Technology(2015S13)
文摘Two new coordination polymers containing rigid bis（triazole）, namely, [Ni（btb）_（0.5）（nph）（H_2O）]_n（1） and [Zn（btb）（SO_4）]_n（2）（btb = 4,4a-bis（1,2,4-triazolyl-1-yl）-biphenyl, H_2nph = 3-nitrophthalic acid） have been synthesized and characterized by elemental analysis, IR spectra, and single-crystal X-ray diffraction. Complex 1 shows a 3D trinodal（3,4,4）-connected sqc69 topology. Complex 2 presents a 2D uninodal 4-connected sql network, which is further packed into a 3D supramolecular framework by C-H···O hydrogen bonds. Thermal stabilities and fluorescence properties of two complexes have been discussed in detail.
基金supported by the National Natural Science Foundation of China(No.21071099)Natural Science Foundation of Guangdong Province(No.2015A030313750)Characteristic Innovation Projects Guangdong Provincial Department of Education(Natural Science Category,2014KTSCX169)
文摘Hydrothermal reactions of 3-cyanopyridine and Na N3 with Zn Cl_2 or Cd Cl_2·5/2H_2 O in the presence of 1,4-benzenedicarboxylic acid（H2bdc） yielded two new coordination polymers,{[Zn（3-ptz）（bdc）_（0.5）（H_2O）_2]n·2H_2O}_n（1） and [Cd_2（3-ptz）_2Cl_2]_n（2）,based on in situ synthesized 5-（3-pyridyl）tetrazolate（3-ptz-） organic ligand.They have been structurally characterized by elemental analysis（EA）,infrared spectroscopy（IR） and single-crystal/powder X-ray diffraction（PXRD）.In 1,two Zn（Ⅱ） ions are linked together through two μ_2-（3-ptz-） ligands to form a dimeric unit of [Zn（μ_2-3-ptz）（H_2O）_2]2^2＋,which is further connected with other equivalent units by μ_2-bdc^2-spacers,resulting in an infinite 1D polymeric chain of [Zn_2（3-ptz）_2（H_2O）_2（bdc）]_n,and then strong hydrogen bonding interactions extend these 1D chains into a 3D supramolecular structure.In 2,the Cd（Ⅱ） ions are connected through μ_4-（3-ptz-） ligands and Cl-anions,leading to infinite 2D layers of [Cd_2（3-ptz）Cl_2]_n^n＋,which are further linked by another μ_4-（3-ptz-） pillared ligand to form a 3D layered-pillared framework architecture of [Cd）2（3-ptz））2Cl）2]）n.Furthermore,thermal stability of these compounds was measured by thermogravimetric analysis（TGA） and their photoluminescent properties were also investigated in the solid state at room temperature.
基金supported by the National Natural Science Foundation of China(Grant No.52372283)China Postdoctoral Science Foundation(Grant No.2023M730826)+1 种基金Heilongjiang Postdoctoral Fund(Grant No.LBH-Z23121)Postdoctoral Fellowship Program of CPSF(Grant No.GZC20233425).
文摘Single-atom materials have demonstrated attractive physicochemical characteristics.However,understanding the relationships between the coordination environment of single atoms and their properties at the atomic level remains a considerable challenge.Herein,a facile waterassisted carbonization approach is developed to fabricate well-defined asymmetrically coordinated Co–N_(4)–O sites on biomass-derived carbon nanofiber(Co–N_(4)–O/NCF)for electromagnetic wave(EMW)absorption.In such nanofiber,one atomically dispersed Co site is coordinated with four N atoms in the graphene basal plane and one oxygen atom in the axial direction.In-depth experimental and theoretical studies reveal that the axial Co–O coordination breaks the charge distribution symmetry in the planar porphyrin-like Co–N_(4) structure,leading to significantly enhanced dielectric polarization loss relevant to the planar Co–N_(4) sites.Importantly,the film based on Co–N_(4)–O/NCF exhibits light weight,flexibility,excellent mechanical properties,great thermal insulating feature,and excellent EMW absorption with a reflection loss of−45.82 dB along with an effective absorption bandwidth of 4.8 GHz.The findings of this work offer insight into the relationships between the single-atom coordination environment and the dielectric performance,and the proposed strategy can be extended toward the engineering of asymmetrically coordinated single atoms for various applications.
文摘Density functional theory is used to investigate the complexes structures and properties of poly(vinyl ethylene carbonate)(PVEC/LiTFSI)and poly(vinylene carbonate)(PVCA/LiDFOB)electrolytes containing five-membered ring carbonate groups under the polymer/Li^(+)model and the polymer/lithium salt model.In addition,the calculated and experimental values of the oxidation potentials of the two electrolytes were compared,and the reasons for the differences in the oxidation potentials of the two electrolytes are elucidated.The calculation results show that the PVEC/LiTFSI has more free ion structures and diverse coordination structures compared to PVCA/LiDFOB electrolyte.This provides a reasonable theoretical explanation for its higher ionic conductivity and lower cation mobility number.The PVEC/LiTFSI electrolyte has a lower oxidation potential compared to the PVCA/LiDFOB electrolyte,which is attributed to the proton transfer that occurs during its oxidation.
文摘Photocatalytic decomposition of sugars is a promising way of providing H_(2),CO,and HCOOH as sus-tainable energy vectors.However,the production of C_(1) chemicals requires the cleavage of robust C−C bonds in sugars with concurrent production of H_(2),which remains challenging.Here,the photo-catalytic activity for glucose decomposition to HCOOH,CO(C_(1) chemicals),and H_(2) on Cu/TiO_(2)was enhanced by nitrogen doping.Owing to nitrogen doping,atomically dispersed and stable Cu sites resistant to light irradiation are formed on Cu/TiO_(2).The electronic interaction between Cu and nitrogen ions originates valence band structure and defect levels composed of N 2p orbit,distinct from undoped Cu/TiO_(2).Therefore,the lifetime of charge carriers is prolonged,resulting in the pro-duction of C_(1) chemicals and H_(2) with productivities 1.7 and 2.1 folds that of Cu/TiO_(2).This work pro-vides a strategy to design coordinatively stable Cu ions for photocatalytic biomass conversion.
基金supported by the National Key Research and Development Program of China(Grant No.2020YFA0715000)the National Natural Science Foundation of China(Grant No.52127816)+2 种基金supported by the U.S.Department of Energy(DOE),Office of Energy Efficiency and Renewable Energy,Vehicle Technologies Officethe DOE Office of Science by UChicago Argonne LLC under contract no.DE-AC02-06CH11357the Advanced Photon Source(APS),a U.S.Department of Energy(DOE)Office of Science User Facility,operated for the DOE Office of Science by Argonne National Laboratory under Contract No.DE-AC02-06CH11357
文摘The Fe-N-C material represents an attractive oxygen reduction reaction electrocatalyst,and the FeN_(4)moiety has been identified as a very competitive catalytic active site.Fine tuning of the coordination structure of FeN_(4)has an essential impact on the catalytic performance.Herein,we construct a sulfur-modified Fe-N-C catalyst with controllable local coordination environment,where the Fe is coordinated with four in-plane N and an axial external S.The external S atom affects not only the electron distribution but also the spin state of Fe in the FeN_(4)active site.The appearance of higher valence states and spin states for Fe demonstrates the increase in unpaired electrons.With the above characteristics,the adsorption and desorption of the reactants at FeN_(4)active sites are optimized,thus promoting the oxygen reduction reaction activity.This work explores the key point in electronic configuration and coordination environment tuning of FeN_(4)through S doping and provides new insight into the construction of M-N-C-based oxygen reduction reaction catalysts.
