Design And Research Of Several Oxygen Electrodes Based On Carbon Materials

With energy crisis and serious environmental problems caused by the massive consumption of fossil fuels,proton exchange membrane fuel cells?PEMFC?are becoming the focus of renewable energy technology development due to the advantages of no pollution,high power density,and low temperature operation.In the marine field,fuel cells can assist diesel engines in power supply.Pt/C catalysts are still widely used in cathode catalysts,and the high cost of precious metals impedes the large-scale application of fuel cells.In this paper,first-principle method is used to study a series of non-noble metal doped carbon material catalysts,and the catalytic performance is analyzed from the perspective of thermodynamics,these provides a theoretical basis for the design and synthesis of catalytic materials.The article focuses on the following:1.The catalytic activity of TM₃?HHTP?₂ monolayer?TMX4,which TM = Fe,Co,Ni,X = O,S,Se?was studied.According to adsorption energy of the reaction intermediates,its adsorption strength decreases in the order of Fe,Co,Ni.The activity of metal center of Ni/Fe systems is relatively less affected by their ligands,and the change values of their ORR overpotentials are less than 0.10 V and 0.15 V,respectively.As the ligand changes from O/S to Se,the adsorption energy of OOH and OH in Co system is significantly weakened.The ORR/OER overpotential of Co O4 and Co S4 is located at the apex of the volcano curve,their adsorption strength is moderate,and overpotential is the smallest.2.The electrocatalytic activity of TM/O_x doped graphene?TM = Fe,Co,Ni,Cu,x = 1,2,3,4?was studied,in which Ni O2-pen doped graphene catalyst has low overpotential and good stability.According to the Pauli's exclusion principle,the 4?* anti-bonding orbitals of Ni C4,Ni O1,Ni O2-pen and Ni O2-opp are full,and the electron repulsion increases,which weakens the adsorption capacity of the intermediate product.In addition,as the O coordination number increases,the binding energy generally shows a downward trend,and the catalytic activity of TM/O moiety is inversely proportional to the binding energy.The enhancement of binding energy weakens the adsorption capacity of the active center to a certain extent,and reduces the corresponding overpotential,which has reference significance for the design and screening of single-atom catalysts.3.The electrocatalytic performance of TMN4 doped substrates?graphene,graphane and fluorographene?was systematically studied.In addition to Ni N4 anchored graphane,graphene functionalization significantly reduces the adsorption energy of the active part of TMN4,of which fluorographene doped with Fe N4 has the best ORR catalytic performance.Second,the adsorption energy of OH has a linear relationship with the d-band center.In addition,graphene functionalization strengthens the pd orbital coupling of TM and its coordinated N atoms,and improves stability greatly.The sp hybridization makes the N-p orbital be adjusted by the adjacent C-p orbital,indicating that H/F atom modification can change the electronic structure of TM active center of graphene through C,N atom and improve the catalytic performance.