Cu-doped phosphorene as highly efficient single atom catalyst for CO oxidation: A DFT study

Abstract

Abstract Cu embedded phosphorene is evaluated as single-atom catalyst through DFT calculations for carbon monoxide oxidation reaction. Furthermore, the energy and structural behavior of this catalyst is also studied. We adopted Langmuir-Hinshelwood (LH) mechanism, Eley-Rideal (ER) mechanism and Trimolecular Eley-Rideal (TER) mechanism for CO oxidation by employing Cu embedded phosphorene catalyst. In the LH mechanism (CO + O2 → OOCO → CO2 + O*), the activation energy barrier for the formation of peroxy type intermediate OOCO is 15.36 kcal/mol. Furthermore, this intermediate is dissociated into CO2 and O* in the rate-limiting step with an energy barrier of 5.91 kcal/mol. In the ER mechanism (CO + O2 → CO3 → CO2 + O*), a carbonate-like intermediate is formed after the adsorption of the CO molecule over the pre-adsorbed O2 molecule. The activation energy barrier for the formation of this intermediate is 52.54 kcal/mol. This intermediate is dissociated into CO2 molecule and O* moiety in the rate-limiting step with an energy barrier of 28.46 kcal/mol. In the TER mechanism (2CO + O2→ OCO-OCO → 2CO2), an O2 molecule is activated over the pre-adsorbed two CO molecules and an intermediate OCO-OCO is formed. The activation energy for this reaction is only 2.27 kcal/mol. This intermediate is further dissociated into two CO2 molecules after the elongation of bond length of O2 from 1.41 A to 1.57 A with an energy barrier of 7.36 kcal/mol as a rate-limiting step. Ultimately, these two CO2 molecules are desorbed from the surface of the catalyst and -104.84 kcal/mol is released exothermically. Hence, the results manifest that Cu-embedded phosphorene is a promising and highly activated catalyst for CO oxidation by following the TER mechanism.