Co-doped triel-pnicogen graphene as metal-free catalyst for CO oxidation: Role of multi-center covalency.

Abstract

Third and fifth group atoms, named triel and pnicogen, respectively, were used for graphene doping. AlP and AlN structures were selected as co-doped graphene-based catalysts. The electronic structure and catalytic properties of binary AlN, AlP co-doped graphene were investigated through density functional theory (DFT). Results show that the AlP co-doped graphene strictly enhances the oxygen reactivity compared to AlN one. The CO oxidation on AlP and AlN co-doped graphene sheets is mainly done through Eley-Rideal mechanism as follows: CO + O2➔CO2 + Oads and CO + Oads➔ CO2. The CO oxidation reaction paths over the AlN and AlP-co-doped graphene have revealed that they can be regarded as the competent catalyst for CO oxidation in the presence of O2. Mechanistically, both AlP and AlN co-doped graphene catalysts are appropriately active in the first step while the second step is too hard to do regarding the multi-center covalency character between O2 and AlP co-doped graphene and hence its catalytic efficiency is significantly lower compared to AlN co-doped graphene sheet. Thus, the substitution of a C-C bond with Al-N is an effective way to design the graphene-based catalysts for CO oxidation.