基于密度泛函理论的S掺杂碳载体负载Pt催化剂对氧还原反应的影响

Effects of the S-Doped Carbon Supported Pt Catalyst on Oxygen Reduction Reaction by Density Functional Theory

采用密度泛函方法对比研究了Pt/C催化剂中碳载体掺S前后对氧还原反应(ORR)的影响。从电荷分布、态密度及d带中心等性质出发,分析了金属-载体间相互作用,研究了ORR各物种在催化剂上的吸附并计算了ORR过电势。结果表明:S掺杂使得碳载体表面发生了电子转移,S上的电子转移到邻近的C原子上,负载Pt纳米颗粒后,Pt金属上的电子转移给了碳载体;Pt在S掺杂碳载体上的吸附更强,形成了Pt—C键和Pt—S键,Pt纳米颗粒的分散度和稳定性得到了提升;掺S使得催化剂d带中心下降,对ORR各中间体的吸附减弱,ORR过电势降低,表明掺S能提高催化剂的催化活性。

The effects of S-doped and un-doped carbon supported Pt catalysts on oxygen reduction reaction(ORR)were studied by density functional theory.The metal-support interaction was analyzed from three aspects:charge distribution,density of states and d-band center.Moreover,the adsorption of ORR intermediates on catalysts was studied,and the overpotential of ORR was calculated.The results show that S-doping caused electrons transfer on the surface of carbon carrier,and the electrons on S were transferred to adjacent C atoms.After loading Pt particles,the electrons on Pt metal were transferred to carbon carrier.This also suggests that the adsorption of Pt on S-doped carbon carrier is stronger,thus forming the Pt—C and Pt—S bonds,and further enhancing the dispersion and stability of Pt nanoparticles.Then S-doping lowers d-band center of the catalyst,thus weakening the adsorption of ORR intermediates,and decreasing the overpotential of ORR,which indicates that the catalytic activity of catalyst can be improved by doping S.