Study On The Synthesis And Device Application Of Carbon-based Oxygen Reduction Catalysts For Electrochemical Preparation Of Hydrogen Peroxide

The electrochemical preparation of hydrogen peroxide based on the2-electron oxygen reduction reaction（2e^-ORR）has become an important research direction in the current frontier research field due to its high safety,atomic economy,and environmental friendliness.Carbon-based materials are a promising class of 2e^-ORR electrocatalysts due to their low cost,good selectivity,and high electrical conductivity.However,the current pristine carbon materials have poor selectivity and activity for 2e^-ORR,and the materials have low spatiotemporal yields for electrochemical synthesis of hydrogen peroxide in classical diaphragm electrolyzers,which cannot meet the needs of large-scale preparation.Therefore,in this paper,through the surface functional group modification and pore structure construction of carbon-based materials,the structure-activity relationship was explored and the optimal selection was made.The catalyst is used in a new electrochemical synthesis of hydrogen peroxide device with three chambers,and the optimal preparation efficiency is obtained in combination with the optimization of the device process.The main contents obtained are detailed as follows:（1）Oxygen-functionalized Vulcan XC-72R（O-Vulcan XC-72R）catalysts with different oxidation degrees were obtained by treating carbon materials with nitric acid.The effect of surface oxidation on the electrochemical performance of the catalysts was investigated.O-Vulcan XC-72R-0.5 was selected to have excellent hydrogen peroxide selectivity and ORR activity,and the selectivity was 83-94%in the potential range of 0.4-0.75 V（vs.RHE）.The effect of catalyst structural properties on performance was also explored by the oxidative treatments of different carbons,and it was speculated that the10-20 nm pores had a positive effect on hydrogen peroxide generation.N-doped mesoporous carbon nanoparticle（NMCN）was further synthesized by template method,and the catalysts were oxidized and partially reduced to obtain catalysts O-NMCN-2.0-3 and H₂-O-NMCN-2.0-3.Rotating ring disk electrode（RRDE）tests on the catalysts found that NMCN-2.0 showed 77-81%2e^-ORR selectivity.The oxidized catalyst had good dispersibility and hydrophilicity.The H₂-treated catalyst H₂-O-NMCN-2.0-3 has a certain improvement in H₂O₂activity and selectivity,which may be due to the increase of active sites on the catalyst surface.（2）O-Vulcan XC-72R was used as the cathode catalyst for the electrocatalytic hydrogen peroxide production device,and commercial Pt/C（60%）was used as the anode catalyst.The current density corresponding to the set voltage of-1.5V（-1.0V）and the generation rate of hydrogen peroxide in the test process were taken as performance evaluation criteria.By changing the preparation conditions of MEA and optimizing the components,the performance of the device was improved from the aspects of membrane electrode,the solid electrolyte layer,water flow rate between plates,and test temperature.The highest yield of hydrogen peroxide was 2.68 mmol·h·cm^-2.When tested at 30°C,the device is more stable and hydrogen peroxide does not decompose at a rapid rate.The preparation method of membrane electrode can conduct protons to a greater extent by doping large and small solid electrolytes between suitable thickness solid electrolyte plates,and control the moderate flow rate of water between plates,which can improve the performance of electrocatalytic hydrogen peroxide devices in a certain range.