Preparation And Application Of Iron-carbon Materials And Bismuth Vanadate

Electrochemical technology,such as electrocatalytic oxygen reduction,electro-Fenton,electro-oxidation,and electro-reduction,has the advantages of simple operation,high energy conversion rate,environmental protection and so on.It has been widely applied in the field of environmental pollution protection.Electrocatalyst is the core of electrocatalysis technology.Noble metal catalysts have excellent performance,but they are expensive and have limited earth content.And non-noble metal catalysts have poor activity and unstable performance.Therefore,developing new types of electrocatalysts with high efficiency,low cost and ample contents is the crucial part of further popularizing this technology.Aiming at these problems,this study prepared bismuth vanadate by grinding method,and explored its performance of electrocatalytic oxygen reduction to produce hydrogen peroxide in alkaline,neutral and acidic solutions;Combined with HER,the electrochemical reduction of Cr???by foam iron electrode in alkaline solution was investigated.In addition,carboxylic acid-mediated reduction of Cr???in the natural environment is used to repair polluted waters,soil,etc.Drawn lessons from this,we established an Fe/N-CNTs/formic acid system to catalyze the reduction of Cr???,which greatly improves the performance of Cr???reduction.The main research contents are shown as follows:?1?The bismuth vanadate nanoparticles were prepared by grinding method,and the performance of electrocatalytic oxygen reduction to produce hydrogen peroxide was investigated.The morphology and crystal form of bismuth vanadate were adjusted by changing the dosage and dosing sequence of sodium acetate.The H₂O₂selectivity of bismuth vanadate in alkaline,neutral,and acidic media was measured by rotating disk electrode?RRDE?technology to be 68%,86%,and 4.4%,respectively.While,in the actual process of preparing H₂O₂,the working electrode prepared by Bi VO₄has the highest H₂O₂generation rate in acidic medium,and the H₂O₂concentration is as high as 1.74 mmol/L in 50 minutes.?2?The electro-reduction performance of Cr???under the alkaline conditions was investigated by using an electrochemical workstation and a three-electrode system.The foamed iron and the stainless-steel mesh as counter electrodes,and three different current densities on the removal rate of Cr???were investigated.Combined with HER,the mechanism of Cr???removal by foamed iron as electrodes under alkaline conditions was further explored.The results showed that the reaction rate of the foamed iron as the counter electrode is more than 8 times that of the stainless-steel mesh.With foamed iron as the counter electrode and the working electrode,when the current density is 3 m A/cm²,the effect of electroreduction to remove Cr???is the best,and the removal rate reaches 97.89%at 80 min.?3?Core-shell structured Fe/N-CNTs was synthesized prepared by hydrothermal method,and the performance towards reduction of Cr???to Cr?III?mediated by formic acid was investigated.Fe/N-CNTs/formic acid system has a better effect of removing Cr???than Fe/N-CNTs/oxalic acid system.The reduction efficiency improved with the increasing catalyst dosage within a certain range.It is the same as the formic acid concentration and the initial Cr???concentration.With the optimal conditions,the removal rate of Cr???was 84.52%in 10 minutes and 87.12%in 30minutes.