Study On The Electrocatalytic Performance And Mechanism Of CO₂RR,HER,and OER On The Metal-doped Two-Dimernsional Materials

As developing of the social economy,it becomes more and more serious for the energy shortage and environmental pollution.Recently,the production of the renewable energy and the CO₂ conversion are the effective alternative.Therefore,to solve the problems,the electrocatalytic CO₂ reduction and H₂ production has been focused by the scientists.However,the electrocatalysts with excellent performance are still scarce,which restricts the widely utilization of electrocatalysis.In this work,using the density functional theory（DFT）simulations,the electrocatalytic CO₂RR,HER and OER are studied on surfaces of the two-dimensional materials doped with metal,and the electronic structure properties are analyzed to evaluating the effects of different materials on the mechanisms.The detailed calculation results are shown as follows:1)The single Ru atom and small cluster of Ru₃ are doped in the 2D materials,such as graphene（GR）,hexagonal boron nitride（h-BN）,graphdiyne（GD）and graphite phase carbon nitride（g-C₃N₄）,forming the electrocatalyst of CO₂ reduction.The results shown that the HER isn’t competited with CO₂RR on the models of Ru@GR（C）,Ru@BN（B）and3Ru@C₃N₄;while that is competited on Ru@GD（C）,Ru@C₃N₄（N）and3Ru@GD,although their active sites are different.Totally,almost of the catalysts are excellent for the CO₂RR with lower overpotential of 0.60 eV,excepting for the 3Ru@C₃N₄.2)For Ru@2D models,the Ru@GR（C）（η=0.20 eV）is the optimal catalyst for HER.Then,for comparison with Ru@2D,the performance of electrocatalytic HER are investigated on the pure 2D materials of GR,h-BN,GD,g-C₃N₄ and N@GR,as well as the GR doped with single atom of Pt,Fe,Co and Ni.The results shown that all the M@GR models of Ru@GR（C）,Pt@GR（C）,Fe@GR（C）,Co@GR（C）and Ni@GR（C）can be used as better HER catalysts（-0.35 eV<η<0.20 eV）;especially for the Fe@GR（C）,itsΔG_*H（η=0.05 eV）is very close to the optimal valueindicating the GR is a excellent substrate of the HER catalyst.3)Relatively,the calculations of the OER performance show that the GR（η=0.69 eV）and g-C₃N₄（η=0.89 eV）doped with single atom Ru are excellent catalysts of Ru@2D.Subsequently,the OER performances of Pt@GR（C）,Fe@GR（C）,Co@GR（C）and Ni@GR（C）are investigated and compareed with Ru@GR（C）.The results show that the Ru@GR（C）still has the best OER performance.In addition,the CN materials doped with metal are constructed and compared with Ru@C₃N₄（N）,and the results show that the models of Co N₄@GR,Pt@C₃N₄（N）,Co@C₃N₄,Co@C₃N₄（N）and Ru@C₃N₄（N）possess the excellent performance of OER（η<0.95 eV）.Based on the calculations,it is found that the rate determination step on the almost catalysts is H₂O+*O→*OOH+H⁺,suggesting that the OER performance of the catalysts is related to the adsorption energy of surface O atom.