Electrochemical N2 reduction offers a promising alternative to the Haber-Bosch process for sustainable NH3 synthesis at ambient conditions,but it needs efficient catalysts for the N2 reduction reaction(NRR).Here,we re...Electrochemical N2 reduction offers a promising alternative to the Haber-Bosch process for sustainable NH3 synthesis at ambient conditions,but it needs efficient catalysts for the N2 reduction reaction(NRR).Here,we report that FeOOH quantum dots decorated graphene sheet acts as a superior catalyst toward enhanced electrocatalytic N2 reduction to NH3 under ambient conditions.In 0.1 M LiClO4,this hybrid attains a large NH3 yield rate and a high Faradaic efficiency of 27.3µg·h^−1·mg−1cat.and 14.6%at−0.4 V vs.reversible hydrogen electrode,respectively,rivalling the current efficiency of all Fe-based NRR electrocatalysts in aqueous media.It also shows strong durability during the electrolytic process.展开更多
Carbon dots(CDs)have been attracted much attention and widely studied due to their excellent fluorescence(FL)properties,better biocompatibility and outstanding photo/chemical stability.However,the disadvantage of lowe...Carbon dots(CDs)have been attracted much attention and widely studied due to their excellent fluorescence(FL)properties,better biocompatibility and outstanding photo/chemical stability.However,the disadvantage of lower quantum yield(QY)still limits its wide application.Herein,we reported a novel and convenient strategy to prepare photo-induced Ag/CDs(p-Ag/CDs)by irradiating the mixed Ag+and hydrophobic CDs(h-CDs)acetone solution with ultraviolet(UV)light.The obtained p-Ag/CDs exhibit a greatly enhanced FL emission together with a blue shift(460 nm)than h-CDs(520 nm).The QY of p-Ag/CDs is measured to be 51.1%,which is 10.4 times higher than that of h-CDs(4.9%),indicating that photo-induced Ag modulation can effectively improve the optical properties of CDs.The mechanisms for the FL enhancement and blue shift of h-CDs are studied in detail.The results prove that the greatly enhanced FL emission is from the generated Ag nanoparticles(AgNPs)by UV light irradiation based on metal-enhanced fluorescence(MEF),and the increased oxygen-contained groups in this process lead to the blue shift in CDs fluorescence.Interestingly,the p-Ag/CDs exhibit higher sensitivity and selectivity for sulfide ions(S2-)detection than that of h-CDs,which have a lower response to S2-.This work not only offers a novel strategy to improve the FL properties of materials but also endows them with new functions and broadens their application fields.展开更多
In this work,the reduction of mercury ions(Hg2+)to elemental mercury(Hg0)was easily achieved using highly reductive carbon dots(r-CDs),which synthesized from sucrose by a simple and cost-effective method.After a caref...In this work,the reduction of mercury ions(Hg2+)to elemental mercury(Hg0)was easily achieved using highly reductive carbon dots(r-CDs),which synthesized from sucrose by a simple and cost-effective method.After a careful mechanistic study,the reduction was probably accomplished with the large numbers of electrons contained in r-CDs rather than the oxidation of its functional groups.Additionally,a3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide(MTT)assay showed that the r-CDs were nontoxic to wildlife and human beings.Consequently,the r-CDs were used as an alternative to toxic reductants(SnCl2 or NaBH4)for the sensitive and in situ determination of mercury by cold vapor gene ration(CVG)coupled to a miniature point discharge optical emission spectrometer(μPD-OES).Limit of detection of 0.05μg/L was obtained for Hg2+,with relative standard deviation(RSD)less than 5.4%at a concentration of 5μg/L.The accuracy of r-CDs induced CVG-μPD-OES was validated by the determination of mercury in a certified reference material(DOLT-5,dogfish liver)and five natural water samples collected from different rivers and lakes in Chengdu City,Since r-CDs are nontoxic and prepared from abundant and inexpensive sucrose,the r-CDs induced CVG-μPD-OES retains the great potential for the inexpensive and enviro nmentally friendly field analysis of mercury in natural water.The accuracy of the proposed method was validated by the analysis of a certified reference material and several water samples with satisfactory results.展开更多
基金supported by the National Natural Science Foundation of China(No.21575137).
文摘Electrochemical N2 reduction offers a promising alternative to the Haber-Bosch process for sustainable NH3 synthesis at ambient conditions,but it needs efficient catalysts for the N2 reduction reaction(NRR).Here,we report that FeOOH quantum dots decorated graphene sheet acts as a superior catalyst toward enhanced electrocatalytic N2 reduction to NH3 under ambient conditions.In 0.1 M LiClO4,this hybrid attains a large NH3 yield rate and a high Faradaic efficiency of 27.3µg·h^−1·mg−1cat.and 14.6%at−0.4 V vs.reversible hydrogen electrode,respectively,rivalling the current efficiency of all Fe-based NRR electrocatalysts in aqueous media.It also shows strong durability during the electrolytic process.
基金the National Natural Science Foundation of China(Nos.U1833202 and 21876117)the Open Research Fund of the School of Chemistry and Chemical Engineering,Henan Normal University(No.2021YB05).
文摘Carbon dots(CDs)have been attracted much attention and widely studied due to their excellent fluorescence(FL)properties,better biocompatibility and outstanding photo/chemical stability.However,the disadvantage of lower quantum yield(QY)still limits its wide application.Herein,we reported a novel and convenient strategy to prepare photo-induced Ag/CDs(p-Ag/CDs)by irradiating the mixed Ag+and hydrophobic CDs(h-CDs)acetone solution with ultraviolet(UV)light.The obtained p-Ag/CDs exhibit a greatly enhanced FL emission together with a blue shift(460 nm)than h-CDs(520 nm).The QY of p-Ag/CDs is measured to be 51.1%,which is 10.4 times higher than that of h-CDs(4.9%),indicating that photo-induced Ag modulation can effectively improve the optical properties of CDs.The mechanisms for the FL enhancement and blue shift of h-CDs are studied in detail.The results prove that the greatly enhanced FL emission is from the generated Ag nanoparticles(AgNPs)by UV light irradiation based on metal-enhanced fluorescence(MEF),and the increased oxygen-contained groups in this process lead to the blue shift in CDs fluorescence.Interestingly,the p-Ag/CDs exhibit higher sensitivity and selectivity for sulfide ions(S2-)detection than that of h-CDs,which have a lower response to S2-.This work not only offers a novel strategy to improve the FL properties of materials but also endows them with new functions and broadens their application fields.
基金the National Natural Science Foundation of China(Nos.2152950121622508 and 21575092)for financial supportthe financial support from the high school talent plan of China Association for Science and Technology。
文摘In this work,the reduction of mercury ions(Hg2+)to elemental mercury(Hg0)was easily achieved using highly reductive carbon dots(r-CDs),which synthesized from sucrose by a simple and cost-effective method.After a careful mechanistic study,the reduction was probably accomplished with the large numbers of electrons contained in r-CDs rather than the oxidation of its functional groups.Additionally,a3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide(MTT)assay showed that the r-CDs were nontoxic to wildlife and human beings.Consequently,the r-CDs were used as an alternative to toxic reductants(SnCl2 or NaBH4)for the sensitive and in situ determination of mercury by cold vapor gene ration(CVG)coupled to a miniature point discharge optical emission spectrometer(μPD-OES).Limit of detection of 0.05μg/L was obtained for Hg2+,with relative standard deviation(RSD)less than 5.4%at a concentration of 5μg/L.The accuracy of r-CDs induced CVG-μPD-OES was validated by the determination of mercury in a certified reference material(DOLT-5,dogfish liver)and five natural water samples collected from different rivers and lakes in Chengdu City,Since r-CDs are nontoxic and prepared from abundant and inexpensive sucrose,the r-CDs induced CVG-μPD-OES retains the great potential for the inexpensive and enviro nmentally friendly field analysis of mercury in natural water.The accuracy of the proposed method was validated by the analysis of a certified reference material and several water samples with satisfactory results.
