Investigation of ORR and OER Mechanisms by Co- and Fe-doped Silicon Nanocages (Si48 and Si60) and Co- and Fe-doped Silicon Nanotubes (SiNT(5, 0) and SiNT(6, 0)) as Acceptable Catalysts
摘要
In this work, the catalytic activity of Co-Si48, Co-Si60, Co-SiNT (5, 0), Co-SiNT (6, 0), Fe-Si48, Fe-Si60, Fe-SiNT (5, 0), Fe-SiNT (6, 0) as catalysts of oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) are examined. The Fe doped Si-nanotubes and Si-nanocages have more negative the formation energy and adoption energy values than Co doped Si-nanotubes and Si-nanocages. Results indicated that the reactions step of OOH* creation for OER and OH* elimination for ORR are the potential-determining steps. The *O has the most negative adsorption energy than *OH, *OOH, *H, O2 and H2O species. The H2O is desorbed on Si-nanostructures with low adsorption energy. The Gibbs free energy values of reaction step 1 and step 2 (OH− + Si-nanostructure → Si-nanostructure-*OH + e− → Si-nanostructure -*O + H2O + e−) on Co and Fe doped Si-nanostructures are negative values. The overpotential of ORR processes on Co-Si48, Co-Si60, Co-SiNT (5, 0), Co-SiNT (6, 0), Fe-Si48, Fe-Si60, Fe-SiNT (5, 0), Fe-SiNT (6, 0) in water are 1.24, 1.20, 1.15, 1.11, 1.07, 1.04, 1.00 and 0.97 eV. The metal doped Si-nanotubes and Si-nanocages have acceptable potential to catalyze the OER and ORR reactions.