Preparation Of Ferrocenyl Metal Organic Framework Materials And Their Electrooxidation Performance For Sugars And Alcohol

Electrolysis of water for hydrogen production is a highly efficient and environmentally friendly method.However,the sluggish oxygen evolution reaction(OER)results in a significant voltage gap between the two half-reactions,which hinders the large-scale application of hydrogen energy.To address this issue,the researchers devised a strategy to substitute OER with biomass materials such as glycerol,urea,methanol,glucose and benzyl alcohol.This approach not only offers thermodynamic advantages but also presents more attractive economic prospects.In this study,three metallocene-based organic frameworks were synthesized via solvothermal method using nickel nitrate hexahydrate,copper nitrate trihydrate and cobalt acetate tetrahydrate as metal ion sources while 1,1’-ferrocenedicarboxylic acid and ferroceneformic acid served as ligands for the electrooxidation of glycerol,glucose and benzyl alcohol.The main research contents are as follows:(1)NiFcMOF,Cu FcMOF,NiCu FcMOF(1:1),NiCu FcMOF(1:1.5)and NiCu FcMOF(1:2)electrocatalysts were synthesized on nickel foam via a solvothermal method.The electrochemical properties of these five catalysts for the oxidation of glycerol were investigated under basic conditions.The results indicate that the theoretical voltage required for glycerol oxidation is lower than that for oxygen evolution reaction.NiCu FcMOF(1:1.5)electrocatalyst was employed for the electrooxidation of glycerol with and without 20 m M glycerol,achieving a current density of 10 m A/cm~2 at an anode voltage of 1.46 V and 1.648 V,respectively.The liquid product obtained after a three-hour electrolysis of glycerol at 1.515 V and 1.565V was analyzed using liquid chromatography-mass spectrometry(LC-MS),which revealed that NiCu FcMOF(1:1.5)electrocatalyst effectively oxidized glycerol into tartric acid,glycolic acid,and formic acid.The Faraday efficiencies of tartaric acid,glycolic acid,and formic acid at a voltage of 1.515 V are 10.45%,5.1%,and 83.24%,respectively,with a glycerol conversion rate of 8.66%.At a voltage of 1.565 V,the Faraday efficiencies for tartaric acid,glycolic acid,and formic acid were found to be6.20%,3.26%,and 73.16%respectively with a corresponding glycerol conversion rate of 11.18%.(2)Cu FcMOF electrocatalyst organometallic framework was synthesized on nickel foam via solvothermal method using copper nitrate and 1,1’-ferrocenedicarboxylic acid as precursors.The electrooxidation of the framework under25 m M glucose condition resulted in a significantly higher overpotential for glucose electrooxidation(GEOR)at 1.488 V compared to that of OER at 1.78 V.Liquid chromatography-mass spectrometry(LC-MS)analysis revealed that Cu FcMOF electrocatalyst effectively catalyzed the oxidation of glucose into gluconic acid and arabinose.After electrolysis at 1.465 V for 1,2 and 3 hours,the Faraday efficiencies of gluconic acid were determined to be 9.32%,11.56%,and 12.97%,respectively,while those of arabinose were found to be significantly higher at values of 52.60%,54.75%,and 63.27%.Similarly,after electrolysis at a slightly higher voltage of 1.515 V for the same durations(one hour～three hours),the Faraday efficiency values obtained for gluconic acid decreased substantially to levels of only 14%,6.29%and 4.42%.Meanwhile,the corresponding Faraday efficiencies measured for arabose also declined but remained relatively high with values ranging from37.25%to 26.32%.(3)Co FcMOF electrocatalyst bi-ligand composites were synthesized via solvothermal method utilizing cobalt nitrate,1,1’-ferrocenedicarboxylic acid and ferrocenedicarboxylic acid as precursors.Due to the synergistic effect of the two ligands,the synthesized catalyst exhibits a more abundant structure and properties.Co FcMOF electrocatalyst dispersed droplets were incorporated onto a carbon cloth electrode for benzyl alcohol oxidation.The addition of benzyl alcohol not only endows Co FcMOF(1:0.4)electrocatalyst with low oxidation potential(1.54 V),but also yields value-added chemical product benzyl acid,with a Faraday efficiency of 96.57%and a conversion rate of benzyl alcohol of 6.85%.