A Theoretical Study On Construction And Electrocatalytic Performance Of Molybdenum Disulfide-based Oxygen Reduction Catalyst

The oxygen reduction reaction（ORR）has a key role in various electrochemical energy conversion and storage applications such as fuel cells and metal–air batteries.In principle,ORR can process through direct four-electron transfer pathway,or two-electron transfer pathway,the former pathway is expected to occur to achieve higher.Thus,efficient ORR electrocatalysts are essential for the practical applications of fuel cells by promoting the four-electron pathway O₂ into H₂O.The current bottleneck of fuel cells lies in the sluggish kinetics of ORR at the cathode,which greatly hinders the performance of fuel cells.efficiency than the latter one.Currently,Pt-based materials are the most conventional electrocatalysts employed to promote ORR because of their high activity and low overpotential.However,the high cost,less abundance,poor durability,and poor stability of Pt-based catalysts in an electrochemical environment have imposed great limitation for the large-scale application of fuel cells.Therefore,great efforts have been devoted to searching for inexpensive,durable,and effective ORR catalysts as the repalcement of Pt–based catalysts.In this paper,by using density functional theory（DFT）to calculate and analyze the relative electrical properties of doped molybdenum disulfide-based catalysts,we evaluate the ORR catalytic activity of these catalysts.The detailed results are as follows:（1）By introducing the elemental Pd in the defective MoS₂ monolayer,we have systematically analysed the structures,electronic properties,and ORR/OER catalytic activities of several Pd_n（n=1-6,and 13）nanoparticles anchored on the defective MoS₂monolayer.Our results demonstrated that all these studied Pd_n/MoS₂ systems have good stability and high chemical reactivity for the activation of the O₂ molecule,except the case of Pd₁/MoS₂,and Pd₆/MoS₂ exhibits the best ORR activity among all the studied Pd_n（n=1-6,and 13）nanoparticles anchored on the defective MoS₂ monolayer.,while the anchored Pd₂ cluster is identified as the bifunctional catalyst for ORR and OER.（2）Using density functional theory to study a series of transition metals（V,Cr,Mn,Fe,Co,Ni,Cu,Ru）loaded on the surface of molybdenum disulfide with different configurations S defects Structural stability（1T,2H）,electronic properties and chemical activity.The results show that the catalyst has good thermodynamic stability,Moreover,the adsorption and activation of O₂ on the catalyst is mainly realized through the transfer of electrons,which has a strong influence on the binding and catalytic activation of molecular oxygen,and provides greater possibilities for the subsequent oxygen reduction reaction（ORR）.