The nitrogen-coordinated metal single-atom catalysts(M−N−C SACs)with an ultra-high metal loading synthetized by direct high-temperature pyrolysis have been widely reported.However,most of metal single atoms in these c...The nitrogen-coordinated metal single-atom catalysts(M−N−C SACs)with an ultra-high metal loading synthetized by direct high-temperature pyrolysis have been widely reported.However,most of metal single atoms in these catalysts were buried in the carbon matrix,resulting in a low metal utilization and inaccessibility for adsorption of reactants during the catalytic process.Herein,we reported a facile synthesis based on the hard-soft acid-base(HSAB)theory to fabricate Co single-atom catalysts with highly exposed metal atoms ligated to the external pyridinic-N sites of a nitrogen-doped carbon support.Benefiting from the highly accessible Co active sites,the prepared Co−N−C SAC exhibited a superior oxygen reduction reactivity comparable to that of the commercial Pt/C catalyst,showing a high turnover frequency(TOF)of 0.93 e^(−)·s^(-1)·site^(-1)at 0.85 V vs.RHE,far exceeding those of some representative SACs with a ultra-high metal content.This work provides a rational strategy to design and prepare M−N−C single-atom catalysts featured with high site-accessibility and site-density.展开更多
Calcium ions(Ca^(2+))and manganese ions(Mn^(2+))are essential for sustaining life activities and are key monitoring indicators in drinking water.Developing highly sensitive,selective,and portable detection methods for...Calcium ions(Ca^(2+))and manganese ions(Mn^(2+))are essential for sustaining life activities and are key monitoring indicators in drinking water.Developing highly sensitive,selective,and portable detection methods for Ca^(2+)and Mn^(2+)is significant for water quality monitoring and human health.In this paper,blue fluorescent Ti3C2 MXene-based quantum dots(MQDs,λ_(em)=445 nm)are prepared using Ti_(3)C_(2)MXene as the precursor.Through the chelation effect of ethylene diamine tetraacetic acid(EDTA),a blue and red dual-emission fluorescent probe,MQDs-EDTA-Eu^(3+)-DPA,was constructed.Herein,dipicolinic acid(DPA)acts as an absorbing ligand and significantly enhances the red fluorescence of europium ions(Eu^(3+))at 616 nm through the“antenna effect”.The blue fluorescence of MQDs serves as an internal reference signal.High concentrations of Ca^(2+)can quench the red fluorescence of Eu^(3+)-DPA;Mn^(2+)can be excited to emit purple fluorescence at 380 nm after coordinating with DPA,red fluorescence of Eu^(3+)-DPA serves as the internal reference signal.Based on the above two fluorescence intensity changes,ratiometric fluorescence detection methods for Ca^(2+)and Mn^(2+)are established.The fluorescence intensity ratio(IF_(616)/IF_(445))exhibits a linear relationship with Ca^(2+)in the range of 35-120μmol/L,with a detection limit of 5.98μmol/L.The fluorescence intensity ratio(IF_(380)/IF_(616))shows good linearity with Mn^(2+)in the range of 0-14μmol/L,with a detection limit of 28.6 nmol/L.This method was successfully applied to the quantitative analysis of Ca^(2+)and Mn^(2+)in commercially available mineral water(Nongfu Spring,Ganten,and Evergrande),with recovery rates of 80.6%-117%and relative standard deviations(RSD)of 0.76%-4.6%.Additionally,by preparing MQD-based fluorescent test strips,visual detections of Ca^(2+)and Mn^(2+)are achieved.This work demonstrates the application potential of MQDs in the field of visual fluorescence sensing of ions in water quality.展开更多
Hanyu Xu 1,Xuedan Song 1,*,Qing Zhang 1,Chang Yu 1,Jieshan Qiu 1,2,*1 Liaoning Key Lab for Energy Materials and Chemical Engineering,State Key Laboratory of Fine Chemicals,School of Chemical Engineering,Dalian Univers...Hanyu Xu 1,Xuedan Song 1,*,Qing Zhang 1,Chang Yu 1,Jieshan Qiu 1,2,*1 Liaoning Key Lab for Energy Materials and Chemical Engineering,State Key Laboratory of Fine Chemicals,School of Chemical Engineering,Dalian University of Technology,Dalian 116024,Liaoning Province,China.展开更多
A trinuclear copper complex [Cu_(3)(L2)_(2)(SO_(4))_(2)(H_(2)O)_(7)]·8H_(2)O(1)(HL2=1-hydroxy-3-(pyrazin-2-yl)-N-(pyrazin-2-ylmethyl)imidazo[1,5-a]pyrazine-8-carboxamide) with a multi-substituted imidazo[1,5-a]py...A trinuclear copper complex [Cu_(3)(L2)_(2)(SO_(4))_(2)(H_(2)O)_(7)]·8H_(2)O(1)(HL2=1-hydroxy-3-(pyrazin-2-yl)-N-(pyrazin-2-ylmethyl)imidazo[1,5-a]pyrazine-8-carboxamide) with a multi-substituted imidazo[1,5-a]pyrazine scaffold was serendipitously prepared from the reaction of the pro-ligand of H_(2)L1(N,N'-bis(pyrazin-2-ylmethyl)pyrazine-2,3-dicarboxamide) with CuSO_(4)·5H_(2O) in aqueous solution at room temperature.Complex 1 was characterized by IR,single-crystal X-ray analysis,and magnetic susceptibility measurements.Single-crystal X-ray analysis reveals that the complex consists of three Cu(Ⅱ) ions,two in situ transformed L2~-ligands,two coordinated sulfates,seven coordinated water molecules,and eight uncoordinated water molecules.Magnetic susceptibility measurement indicates that there are obvious ferromagnetic coupling interactions between the adjacent Cu(Ⅱ) ions in 1.CCDC:1852713.展开更多
基金supported by Shanxi Province Science Foundation for Youths(202203021212300)Taiyuan University of Science and Technology Scientific Research Initial Funding(20212064)Outstanding Doctoral Award Fund in Shanxi Province(20222060).
文摘The nitrogen-coordinated metal single-atom catalysts(M−N−C SACs)with an ultra-high metal loading synthetized by direct high-temperature pyrolysis have been widely reported.However,most of metal single atoms in these catalysts were buried in the carbon matrix,resulting in a low metal utilization and inaccessibility for adsorption of reactants during the catalytic process.Herein,we reported a facile synthesis based on the hard-soft acid-base(HSAB)theory to fabricate Co single-atom catalysts with highly exposed metal atoms ligated to the external pyridinic-N sites of a nitrogen-doped carbon support.Benefiting from the highly accessible Co active sites,the prepared Co−N−C SAC exhibited a superior oxygen reduction reactivity comparable to that of the commercial Pt/C catalyst,showing a high turnover frequency(TOF)of 0.93 e^(−)·s^(-1)·site^(-1)at 0.85 V vs.RHE,far exceeding those of some representative SACs with a ultra-high metal content.This work provides a rational strategy to design and prepare M−N−C single-atom catalysts featured with high site-accessibility and site-density.
基金The Tertiary Education Scientific Research Project of the Guangzhou Municipal Education Bureau(2024312227)Innovative and Entrepreneurial Projects of Guangzhou University Students(202411078014)+2 种基金Guangzhou University Open Sharing Fund for Instruments and Equipment(2025)National Major Scientific Research Instrument Development Project(22227804)Sub-subject of the National Key Research Project(2023YFB3210100)。
文摘Calcium ions(Ca^(2+))and manganese ions(Mn^(2+))are essential for sustaining life activities and are key monitoring indicators in drinking water.Developing highly sensitive,selective,and portable detection methods for Ca^(2+)and Mn^(2+)is significant for water quality monitoring and human health.In this paper,blue fluorescent Ti3C2 MXene-based quantum dots(MQDs,λ_(em)=445 nm)are prepared using Ti_(3)C_(2)MXene as the precursor.Through the chelation effect of ethylene diamine tetraacetic acid(EDTA),a blue and red dual-emission fluorescent probe,MQDs-EDTA-Eu^(3+)-DPA,was constructed.Herein,dipicolinic acid(DPA)acts as an absorbing ligand and significantly enhances the red fluorescence of europium ions(Eu^(3+))at 616 nm through the“antenna effect”.The blue fluorescence of MQDs serves as an internal reference signal.High concentrations of Ca^(2+)can quench the red fluorescence of Eu^(3+)-DPA;Mn^(2+)can be excited to emit purple fluorescence at 380 nm after coordinating with DPA,red fluorescence of Eu^(3+)-DPA serves as the internal reference signal.Based on the above two fluorescence intensity changes,ratiometric fluorescence detection methods for Ca^(2+)and Mn^(2+)are established.The fluorescence intensity ratio(IF_(616)/IF_(445))exhibits a linear relationship with Ca^(2+)in the range of 35-120μmol/L,with a detection limit of 5.98μmol/L.The fluorescence intensity ratio(IF_(380)/IF_(616))shows good linearity with Mn^(2+)in the range of 0-14μmol/L,with a detection limit of 28.6 nmol/L.This method was successfully applied to the quantitative analysis of Ca^(2+)and Mn^(2+)in commercially available mineral water(Nongfu Spring,Ganten,and Evergrande),with recovery rates of 80.6%-117%and relative standard deviations(RSD)of 0.76%-4.6%.Additionally,by preparing MQD-based fluorescent test strips,visual detections of Ca^(2+)and Mn^(2+)are achieved.This work demonstrates the application potential of MQDs in the field of visual fluorescence sensing of ions in water quality.
文摘Hanyu Xu 1,Xuedan Song 1,*,Qing Zhang 1,Chang Yu 1,Jieshan Qiu 1,2,*1 Liaoning Key Lab for Energy Materials and Chemical Engineering,State Key Laboratory of Fine Chemicals,School of Chemical Engineering,Dalian University of Technology,Dalian 116024,Liaoning Province,China.
文摘A trinuclear copper complex [Cu_(3)(L2)_(2)(SO_(4))_(2)(H_(2)O)_(7)]·8H_(2)O(1)(HL2=1-hydroxy-3-(pyrazin-2-yl)-N-(pyrazin-2-ylmethyl)imidazo[1,5-a]pyrazine-8-carboxamide) with a multi-substituted imidazo[1,5-a]pyrazine scaffold was serendipitously prepared from the reaction of the pro-ligand of H_(2)L1(N,N'-bis(pyrazin-2-ylmethyl)pyrazine-2,3-dicarboxamide) with CuSO_(4)·5H_(2O) in aqueous solution at room temperature.Complex 1 was characterized by IR,single-crystal X-ray analysis,and magnetic susceptibility measurements.Single-crystal X-ray analysis reveals that the complex consists of three Cu(Ⅱ) ions,two in situ transformed L2~-ligands,two coordinated sulfates,seven coordinated water molecules,and eight uncoordinated water molecules.Magnetic susceptibility measurement indicates that there are obvious ferromagnetic coupling interactions between the adjacent Cu(Ⅱ) ions in 1.CCDC:1852713.
