Research On Two-dimensional Fuel Cell Catalyst

Fuel cell is the most promising energy conversion device,which has the advantages of clean,high-efficiency,low-temperature operation,abundant fuel sources,and mobility.Oxygen reduction reaction（ORR）and hydrogen oxidation reaction（HOR）are electrochemical reactions that occur at the cathode and anode of the fuel cell,respectively.The ORR on the cathode slows down kinetics due to the activation or cleavage of the O=O bond.The current commercial ORR catalyst is Pt/C,but the global platinum reserves are limited.In addition,the HOR activity of platinum group metal catalysts is about two to three orders of magnitude slower in alkalis than in acid electrolytes.This will result in a higher platinum group metal loading on the anode,which is not conducive to the commercialization of fuel cells.Therefore,the development of non-platinum group catalytic materials with high ORR and HOR activity and durability in alkalis is very critical for the commercialization of fuel cells.Generally speaking,a good electrocatalyst has high activity,high surface area,good conductivity and long-term stability.Due to the atomic-level thickness,high specific surface area,and rich surface chemistry of two-dimensional nanomaterials,they have broad application prospects in catalysis.Based on this,this paper uses the advantages of two-dimensional materials to prepare a catalyst with ORR and HOR activity.The main work is as follows:（1）Research on the activity of oxygen reduction catalyst based on two-dimensional metal oxide Mn_xCo_3-xO_{4（0≤x≤3）}.The active sites of the three-dimensional bulk metal oxide are all in the bulk phase,and the active sites are difficult to expose,resulting in low intrinsic activity.Therefore,the development of two-dimensional metal oxides is conducive to fully exposing the active sites in the catalyst bulk phase,thereby improving Its oxygen reduction activity.Add powdered Co（Ac）₂·4H₂O and Mn（Ac）₂·4H₂O to the solution composed of P123,EG,C₂H₅OH and H₂O,and synthesize two-dimensional metal oxide Mn_xCo_3-xO_{4（0≤x≤3）}Catalyst.The catalyst is analyzed by physical characterization such as SEM,and the prepared catalyst has a two-dimensional morphology.Subsequently,the ORR activity of the catalyst was explored by the CV and LSV test methods,and the best performance Mn_0.6Co_2.4O₄oxygen reduction catalyst was obtained.Its thickness is 13 nm.The measured half-wave potential is 802 m V,which is higher than that without Mn.The maximum output power of a single cell measured by using the Mn_0.6Co_2.4O₄ catalyst as the cathode is 837.4 m W cm^-2,which is much better than the commercial Pt/C catalyst.Finally,the methanol oxidation resistance test and accelerated aging test Mn_0.6Co_2.4O₄ catalyst were used to obtain good methanol resistance and stability.（2）Research on the activity of Ru/T_i3C₂ hydrogen oxidation catalyst derived from two-dimensional layered Ti₃C₂ material.Ruthenium has similar properties to platinum,and ruthenium has an ideal price,making it a potential substitute for HOR catalysts.However,metal ruthenium is easily oxidized and cannot be used as a HOR catalyst alone.MXene is a new family of two-dimensional materials,with large specific surface area,good hydrophilicity,electrical conductivity and stability,and rich surface chemistry.It has attracted great attention in the electrochemical process.So use the rich surface chemistry and two-dimensional properties of MXene material as a carrier to modify ruthenium to improve the activity and stability of the ruthenium-based catalyst.On the two-dimensional layered Ti₃C₂ carrier,Ru Cl₃ solution was added,and the Ru/Ti₃C₂ hydroxide catalyst was synthesized by hydrogen reduction at 500℃.The catalyst was analyzed by physical characterization such as SEM,and Ru was successfully loaded onto the two-dimensional layered Ti₃C₂ carrier.CV and LSV electrochemical methods are used to explore the oxygen reduction activity of the catalyst.The two-dimensional layered Ti₃C₂ support has no hydrogen oxidation activity,and it shows better hydrogen oxidation activity after adding 20%Ru.