单原子Zn-N_(x)/C(x=0~4)催化剂活化O_(2)的理论研究

Theoretical study on the activation of O_(2)over single atom Zn-N_(x)/C(x=0~4)catalysts

在GGA-PBE/DNP的理论水平下,构建了Zn单原子和氮原子共掺杂单空位(SG)和双空位(DG)石墨烯催化剂模型,分别记作Zn-N_(x)/SG(x=0~3)和Zn-N/DG(x=0~4)。对于Zn-N_(x)/SG或Zn-N_(x)/DG,随着N原子的增加,其稳定性依次升高。研究了在不同含氮配位环境的Zn-N_(x)/SG和Zn-N_(x)/DG对吸附和活化O_(2)的影响。单空位掺杂的Zn-N_(x)/SG活化O_(2)的程度均强于双空位掺杂的Zn-N_(x)/DG。对于Zn-N_(x)/SG或Zn-N_(x)/DG,随着N原子的逐渐增加,Zn位点的正电荷逐渐增加,d带中心与费米能级的能级差逐渐减小,活化氧气的能力逐渐增强。其中,Zn-N_(3)/SG表现出最强的活化O_(2)的能力。

The single-atom Zn-N_(x)/C(x=0~4)catalyst models were studied at GGA-PBE/DNP level,in which zinc atom was located on monovacancy(SG)and divacancy(DG)defective nitrogen-doped graphene,denoted as Zn-N_(x)/SG(x=0~3)and Zn-N_(x)/DG(x=0~4),respectively.For Zn-N_(x)/SG or Zn-N_(x)/DG,their stabilities increase sequentially with the increasing nitrogen atoms.Toward the activation of O_(2),Zn-N_(x)/SG exhibit stronger activity than Zn-N_(x)/DG.For Zn-N_(x)/SG or Zn-N_(x)/DG,the more the doped nitrogen atoms,the more positive the charge at Zn-site,the less negative the energy level difference(ε_(d))for the center of the d-bands relative to the Fermi level,and the stronger the capability of activating O_(2).Among Zn-N_(x)/SG and Zn-N_(x)/DG,Zn-N_(3)/SG displays the strongest activity,toward the activation of O_(2).