Fluorescence Sensing And Electrocatalytic Hydrogen Evolution Of La^Ⅲ-and Co^Ⅱ-MOFs

Metal organic framework compounds（MOFs）have important potential applications in many research fields due to their large specific surface area and structural design control.In recent years,MOFs can be used as a fluorescent sensing material to identify heavy metal ion contaminants in water.At the same time,derivatives prepared with MOFs as precursor can also be used as non-precious metal catalysts in electrocatalytic hydrogen evolution reaction to reduce the overpotential in the reaction and it can achieve a large-scale production of hydrogen by industrialized electrolyzed water.Therefore,in this paper,we have prepared two kinds of three-dimensional MOFs materials by simple solvothermal synthesis method,and systematically completed their structure,properties and mechanism in fluorescence sensing and electrocatalytic hydrogen evolution reaction.The main contents are as follows:（1）Based on 4,4-（（5-carboxy-1,3-phenylene）bis（oxy））dibenzoic acid（H₃cpbda）and La（NO₃）₃·6H₂O,a 3D porous MOFs,[La（cpbda）（H₂O）_1.5]_n（1）,was synthesized by hydrothermal method and further characterized by singlecrystal X-ray diffraction,PXRD,IR,TGA and fluorescence spectroscopy.Owing to its good stabilities and fluorescence property,the sensing experiments on sixteen cations and eleven anions were implemented.Moreover,the further titration processes show La-MOFs can sensitively detect the Fe（III）cation and Cr（VI）-containing anions by quenching responses.（2）Based on the ZIF framework and the polyacid TO₄ unit,a novel polymetallic hybrid zeolite imidazole skeleton（HZIF-MoCo）was assembled by using dimethylimidazole（2-Mim）as a ligand and transition metal ions（Co）and polyacid compounds（H₂MoO₄）.Subsequently,in order to obtain a bimetallic dopedcarbonnanotube,CoP-Mo₂C@NCcompositecatalyst,the three-dimensional MOFs structure was subjected by two step post-treatment called carbonation and phosphating.The results show that the optimized CoP-MoC₂/NC exhibits a significantly enhanced HER electrocatalytic activity and stability over the entire pH range compared to the conventional catalyst obtained by calcining the precursor directly with a Co or Mo decorated imidazole frame.The optimized hybrid displays superior HER activity which can benefit from the unique porous structure,a high conductivity,as well as the strong interaction of metal-dopant,Mo₂C and in situ formed carbon species.This composite material proposes a new thought for exploring high-efficiency mixed metal HER composite catalyst.