Since graphene-based materials have shown great potential in many fields,it is important to explore ultrafast and high-efficient methods to synthesize reduced graphene oxide(rGO) using inexpensive reducing agents unde...Since graphene-based materials have shown great potential in many fields,it is important to explore ultrafast and high-efficient methods to synthesize reduced graphene oxide(rGO) using inexpensive reducing agents under mild conditions.Here,we reported a novel method for the ultrafast chemical reduction of graphene oxide(GO) at room temperature using sodium borohydride(NaBH_(4)),sodium molybdate(Na_(2)MoO_(4)) and hydrochloric acid(HCl).The reduction was carried out within 2 min.A series of characterization results revealed that the obtained reduced graphene oxide has higher reduction degree than that synthesized by NaBH_(4) alone at high temperature.Moreover,rGO electrode based on the present reducing method exhibited a superior specific capacitance of 139.8 F/g at a current density of1 A/g,indicating that it can be used as electrode materials for supercapacitors.展开更多
A mechanism study on MoO2 electrodeposition from ammonium molybdate solution was presented via linear sweep voltammetry,species distribution diagram,Raman spectra,Fourier transform infrared spectrometry and X-ray diff...A mechanism study on MoO2 electrodeposition from ammonium molybdate solution was presented via linear sweep voltammetry,species distribution diagram,Raman spectra,Fourier transform infrared spectrometry and X-ray diffractometry.The results show that there exist two reducible species in ammonium molybdate aqueous solution,i.e.Mo7 O24^6- and molybdenum ammonium complex.In weak acid medium without NH4^+,an obvious reduction peak denoting the reduction of Mo7 O24^6- to molybdenum(Ⅳ)oxides emerges at around-0.7 V(vs SCE).While in neutral and basic solutions without NH4^+,the dominant species changes to MoO4^2-,and accordingly,no reduction peak appears except hydrogen evolution.NH4^+ plays an important role in MoO2 electrodeposition.A new current peak appears at-1.25 V(vs SCE)in both acid and basic solutions,which is attributed to the reduction of molybdenum complex.The effects of solution composition and the electrodeposition conditions on the current efficiency were discussed systematically.By optimizing the electrodeposition conditions,the current efficiency can reach up to51.9%.展开更多
A one-pot method for the synthesis of uniform Eu^(3+)-doped NaBi(MoO_(4))_(2)nanoparticles with an ellipsoidal shape and tetragonal crystal structure functionalized with polyacrylic acid is reported for the first time...A one-pot method for the synthesis of uniform Eu^(3+)-doped NaBi(MoO_(4))_(2)nanoparticles with an ellipsoidal shape and tetragonal crystal structure functionalized with polyacrylic acid is reported for the first time in the literature.The method is based on a homogeneous precipitation reaction from solutions in an ethylene glycol/water medium containing appropriate bismuth,sodium,and molybdate precursors and polyacrylic acid.The luminescence properties(excitation and emission spectra and luminescence lifetime)of such nanoparticles are evaluated for different Eu^(3+)doping levels,finding an intense red emission for all synthesized samples.The X-ray attenuation properties of the nanoparticles have been also analyzed,which were found to be better than those of a commercially computed tomography contrast agent(iohexol).The dispersibility of the nanoparticles in a physiological medium was also analyzed,finding that they could be well dispersed in a 2-N-morpholinoethanesulfonic acid monohydrate medium(pH=6.5).Finally,the cell viability of such a phosphor has been analyzed using MIA-PaCa-2 cells and its in vivo toxicity has been evaluated using the nematode Caenorhabditis elegans model finding no significant toxicity in both cases up to a nanoparticle concentration of 100μg mL-1,which is within the range required for most in vivo applications.The developed Eu^(3+)-doped NaBi(MoO_(4))_(2)nanoparticles are,therefore,excellent candidates for their use as bimodal probes for luminescence imaging and X-ray computed tomography.展开更多
The design and development of high-performance anodes pose significant challenges in the construction of next-generation rechargeable lithium-ion batteries(LIBs).Sodium molybdate dihydrate(Na_(2)MoO_(4)·2H_(2)O)h...The design and development of high-performance anodes pose significant challenges in the construction of next-generation rechargeable lithium-ion batteries(LIBs).Sodium molybdate dihydrate(Na_(2)MoO_(4)·2H_(2)O)has garnered increasing attention due to its cost-effectiveness,non-toxicity and earth abundance.To enhance the Li storage performance of Na_(2)MoO_(4)·2H_(2)O,a crystallographic orientation regulation strategy is proposed in this work.Initially,density functional theory calculations are carried out to demonstrate that the(020)crystal plane of Na_(2)MoO_(4)·2H_(2)O offers the lowest energy barrier for Li^(+)migration.Subsequently,the preferred crystallographic orientation of Na_(2)MoO_(4)·2H_(2)O crystal is tuned through a low-temperature recrystallization method.Furthermore,the microstructure and phase changes of Na_(2)MoO_(4)·2H_(2)O during the lithiation/de-lithiation process are studied using in situ and ex situ XRD tests,ex situ XPS and cyclic voltammetry to unravel its Li^(+)storage mechanism.Upon application as LIBs anode,the Na_(2)MoO_(4)·2H_(2)O single-crystal particles with a preferred(020)surface exhibit superior reversible capacity,high-capacity retention and high cycling stability.The enhanced Li storage performance should be attributed to the regulated crystallographic orientation and small changes in the crystal microstructure during the charge/discharge process,which facilitates Li^(+)migration and bolsters structural stability.Notably,this study introduces a novel concept and a simple synthesis method for the advancement of electrodes in rechargeable batteries.展开更多
The production of MoO3 from Sarcheshmeh molybdenite concentrate via a pyro-hydrometallurgical process was studied.The molybdenite concentrate and sodium carbonate were premixed and fused under air atmosphere.Then the ...The production of MoO3 from Sarcheshmeh molybdenite concentrate via a pyro-hydrometallurgical process was studied.The molybdenite concentrate and sodium carbonate were premixed and fused under air atmosphere.Then the fused products were leached in water and the dissolved molybdenum was recovered as ammonium molybdate.The ammonium molybdate was then calcined to produce mo-lybdic oxide.At the fusion stage,the effect of the mass ratio of carbonate to sulfide on the reaction products and the solubility of the products was investigated.The results show that during the fusion,sodium molybdate and sodium sulfate are the final reaction products and sodium sulfide is detected as an intermediate reaction product.By melting at 850℃with 5wt%excess carbonate,the maximum solubility of the products is obtained.The molybdenum is recovered from the solutions as ammonium molybdate.展开更多
文摘Since graphene-based materials have shown great potential in many fields,it is important to explore ultrafast and high-efficient methods to synthesize reduced graphene oxide(rGO) using inexpensive reducing agents under mild conditions.Here,we reported a novel method for the ultrafast chemical reduction of graphene oxide(GO) at room temperature using sodium borohydride(NaBH_(4)),sodium molybdate(Na_(2)MoO_(4)) and hydrochloric acid(HCl).The reduction was carried out within 2 min.A series of characterization results revealed that the obtained reduced graphene oxide has higher reduction degree than that synthesized by NaBH_(4) alone at high temperature.Moreover,rGO electrode based on the present reducing method exhibited a superior specific capacitance of 139.8 F/g at a current density of1 A/g,indicating that it can be used as electrode materials for supercapacitors.
基金Project(51374185) supported by the National Natural Science Foundation of China
文摘A mechanism study on MoO2 electrodeposition from ammonium molybdate solution was presented via linear sweep voltammetry,species distribution diagram,Raman spectra,Fourier transform infrared spectrometry and X-ray diffractometry.The results show that there exist two reducible species in ammonium molybdate aqueous solution,i.e.Mo7 O24^6- and molybdenum ammonium complex.In weak acid medium without NH4^+,an obvious reduction peak denoting the reduction of Mo7 O24^6- to molybdenum(Ⅳ)oxides emerges at around-0.7 V(vs SCE).While in neutral and basic solutions without NH4^+,the dominant species changes to MoO4^2-,and accordingly,no reduction peak appears except hydrogen evolution.NH4^+ plays an important role in MoO2 electrodeposition.A new current peak appears at-1.25 V(vs SCE)in both acid and basic solutions,which is attributed to the reduction of molybdenum complex.The effects of solution composition and the electrodeposition conditions on the current efficiency were discussed systematically.By optimizing the electrodeposition conditions,the current efficiency can reach up to51.9%.
基金the I+D+I Grant RTI2018-094426-B-I00 and funded by MCIN/AEI/10.13039/501100011033 and by“ERDF A way of making Europe”R.M.Calderón-Olvera acknowledges the financial support from the CONACYT-801024 postdoctoral grant+5 种基金support from the FPI program(PRE2019-090170)the grant FPU19/00527 funded by MCIN/AEI/10.13039/501100011033 and by“ESF Investing in your future”the FPU predoctoral contract(FPU19/01311)from Ministerio de Educación Cultura y Deporte(Spain)DGA and Fondos Feder(Bionanosurf E15_17R)and CIBER-Consorcio Centro de Investigación Biomédica en Red(CB16/01/00263)Instituto de Salud Carlos III(Spanish Ministry of Science and Innovation and European Commission,European Regional Development Fund)the European Commission NextGenerationEU(Regulation EU 2020/2094).
文摘A one-pot method for the synthesis of uniform Eu^(3+)-doped NaBi(MoO_(4))_(2)nanoparticles with an ellipsoidal shape and tetragonal crystal structure functionalized with polyacrylic acid is reported for the first time in the literature.The method is based on a homogeneous precipitation reaction from solutions in an ethylene glycol/water medium containing appropriate bismuth,sodium,and molybdate precursors and polyacrylic acid.The luminescence properties(excitation and emission spectra and luminescence lifetime)of such nanoparticles are evaluated for different Eu^(3+)doping levels,finding an intense red emission for all synthesized samples.The X-ray attenuation properties of the nanoparticles have been also analyzed,which were found to be better than those of a commercially computed tomography contrast agent(iohexol).The dispersibility of the nanoparticles in a physiological medium was also analyzed,finding that they could be well dispersed in a 2-N-morpholinoethanesulfonic acid monohydrate medium(pH=6.5).Finally,the cell viability of such a phosphor has been analyzed using MIA-PaCa-2 cells and its in vivo toxicity has been evaluated using the nematode Caenorhabditis elegans model finding no significant toxicity in both cases up to a nanoparticle concentration of 100μg mL-1,which is within the range required for most in vivo applications.The developed Eu^(3+)-doped NaBi(MoO_(4))_(2)nanoparticles are,therefore,excellent candidates for their use as bimodal probes for luminescence imaging and X-ray computed tomography.
基金supported by the Natural Science Foundation of Guizhou Province(No.ZK 2022-044)the Platform of Science and Technology and Talent Team Plan of Guizhou Province(No.GCC[2023]007)+1 种基金the National Science Foundation of China(Nos.52101010 and 11964006)the Fund of Natural Science Special(Special Post)Research Foundation of Guizhou University(No.2021-018).
文摘The design and development of high-performance anodes pose significant challenges in the construction of next-generation rechargeable lithium-ion batteries(LIBs).Sodium molybdate dihydrate(Na_(2)MoO_(4)·2H_(2)O)has garnered increasing attention due to its cost-effectiveness,non-toxicity and earth abundance.To enhance the Li storage performance of Na_(2)MoO_(4)·2H_(2)O,a crystallographic orientation regulation strategy is proposed in this work.Initially,density functional theory calculations are carried out to demonstrate that the(020)crystal plane of Na_(2)MoO_(4)·2H_(2)O offers the lowest energy barrier for Li^(+)migration.Subsequently,the preferred crystallographic orientation of Na_(2)MoO_(4)·2H_(2)O crystal is tuned through a low-temperature recrystallization method.Furthermore,the microstructure and phase changes of Na_(2)MoO_(4)·2H_(2)O during the lithiation/de-lithiation process are studied using in situ and ex situ XRD tests,ex situ XPS and cyclic voltammetry to unravel its Li^(+)storage mechanism.Upon application as LIBs anode,the Na_(2)MoO_(4)·2H_(2)O single-crystal particles with a preferred(020)surface exhibit superior reversible capacity,high-capacity retention and high cycling stability.The enhanced Li storage performance should be attributed to the regulated crystallographic orientation and small changes in the crystal microstructure during the charge/discharge process,which facilitates Li^(+)migration and bolsters structural stability.Notably,this study introduces a novel concept and a simple synthesis method for the advancement of electrodes in rechargeable batteries.
文摘The production of MoO3 from Sarcheshmeh molybdenite concentrate via a pyro-hydrometallurgical process was studied.The molybdenite concentrate and sodium carbonate were premixed and fused under air atmosphere.Then the fused products were leached in water and the dissolved molybdenum was recovered as ammonium molybdate.The ammonium molybdate was then calcined to produce mo-lybdic oxide.At the fusion stage,the effect of the mass ratio of carbonate to sulfide on the reaction products and the solubility of the products was investigated.The results show that during the fusion,sodium molybdate and sodium sulfate are the final reaction products and sodium sulfide is detected as an intermediate reaction product.By melting at 850℃with 5wt%excess carbonate,the maximum solubility of the products is obtained.The molybdenum is recovered from the solutions as ammonium molybdate.
