| Metal-organic frameworks(MOFs)were a sort of crystalline organic-inorganic hybrid functional materials self-assembled by metal cation/ion clusters and organic ligands,which not only maintain good stability and purity,but also have diverse structures,regular pore channels,adjustable metal sites and pores,and are an ideal class of electrode materials.Metal ions/ion clusters can look upon as active sites for catalytic reactions and redox reactions,and functional groups in organic ligands(COO-,etc.)and the conjugate system can form hydrogen bonds with small biological molecules(such as uric acid,dopamine,etc.)or attract each other through?-?interaction.Due to its poor electrical conductivity,the conductive carbon black(CB)was doped into MOFs by physical grinding method to study its electrochemical properties in this paper.n this paper,five complexes with novel structure and stable chemical properties were synthesized by using Cu(?)and Co(?)ions and nitrogen-containing ligands and carboxylic acid ligands,and the correlation analysis is carried out.The study is described in the following sections:1.1-(tetrazo-5-yl)-4-(triazo-1-yl)benzene(HTTB),3,5-di(2',4'-dicarboxylphenyl)benzoic acid(H5L),1,10-phenanthroline(phen),2,2'-bipyridine(bpy),bis(pyrid-4-ly)biphenyl(4,4'-bibp)were selected with metal-centered Cu(?)cations by hydrothermal method using a self-assembly strategy to synthesize 4 novel complexes,namely,{[Cu2(TTB)(SO4)(OH)]·H2O·Me CN}n(1),[Cu2(?2-H3L)(phen)2](2),[Cu2(?2-H3L)2(bpy)2]{[Cu4(?4-HL)4(bpy)4(H2O)](DMF)}n(3)and{[Cu0.5(?2-H3L)0.5(4,4'-bibp)][Cu0.5(?2-H3L)0.5(4,4'-bib p)]}n(4).XRD results show that complex 1 was a 2D layered structure composed of a unique 1D{Cu2(Tetrazole)(SO4)(OH)}n cluster,which was further expanded into 3D supramolecular structure by hydrogen bonding.The complexes 2-4 were1D structures,which were composed of binuclear Cu structures.However,the binuclear Cu structures had different structures due to the different steric effects of auxiliary ligands(such as phen,bpy and 4,4'-bibp).The electrochemical catalytic hydrolysis performance of(1-4)/CB@NF electrode composed of CB and compound 1-4 loaded with NF by grinding method was studied.The electrocatalytic research showed that the 1/CB@NF electrode showed better OER performance than Ru O2@NF,reaching a current density of 10 m A·cm-2when the overpotential of OER was 377 m V in 1.0 M KOH electrolyte,with the Tafel slope of 1/CB@NF was 15.6 m V·dec-1.Meanwhile,the overpotential of HER was 242 m V at a current density of 10 m A·cm-2,with the Tafel slope being 23.1 m V·dec-1,also suggested the HER performance of 1/CB@NF was better than that of Pt/C@NF.The durability test manifested the electrocatalytic activity of 1/CB@NF can maintain 90%after 12 h in 1.0 M KOH.The electrocatalytic properties showed that 1 is an excellent candidate multifunctional material in energy conversion.In addition,the electrochemical experimental results of complexes 2-4 show that the 2/CB@NF electrode had the best electrochemical performance among the three materials,even better than the noble metals Pt/C@NF and Ru O2@NF.The2/CB@NF electrode reached a current density of 10 m A cm-2 in 1.0 M KOH solution requiring an overpotential of only 421 m V during OER.Meanwhile,the overpotential of the2/CB@NF electrode is only 227 m V during the HER process.The Tafel slopes of 2/CB@NF in HER and OER processes were 18.6 and 25.3 m V dec-1,respectively.The corrosion resistance experiment showed that the 2/CB@NF electrode had outstanding stability.2.The Co(?)cation and aromatic?-conjugated triphenyl-3,2",5",3"-tetracarboxylic acid ligand(H4TATP)were used to construct the complexes by a mixed-ligand strategy and hydrothermal method,namely,[Co3(?3-O)2(TATP)(H2O)4](5).The structural characterization revealed that the complex 5 was a three-dimensional structure consisting of 1D rod-shaped[Co3(COO)4(?3-O)2]n SBUs.The modified 5/CB/GCE sensor was made up with 5 and CB are applied dropwise to the GCE electrode by using a modified glassy carbon electrode(GCE)strategy.And the prepared modified electrode of 5/CB/GCE showed remarkable electrochemical sensing performances for detect UA in PBS solution(p H=7)with high sensitivity,high selectivity,good recyclability,large detection range(0.4-400?M),excellent anti-interference,and low detection limit of 3.4 ppb through electrocatalytic oxidation effects.Whether in urine or serum,the 5/CB/GCE sensor can accurately detect the levels of UA.This work demonstrates MOFs-based composite materials had great potentials in the clinical medicine,thereby providing a new way to design and develop the electrochemical sensors or biosensors. |
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