A Comparative Study of CO Oxidation on Nitrogen- and Phosphorus-Doped Graphene

The geometry, electronic structure, and catalytic properties of nitrogen- and phosphorus-doped graphene (N-/P-graphene) are investigated by density functional theory calculations. The reaction between adsorbed O-2 and CO molecules on N- and P-graphene is comparably studied via Langmuir-Hinshelwood (LH) and Eley-Rideal (ER) mechanisms. The results indicate that a two-step process can occur, namely, CO+O-2 -> CO2-O-ads and CO-O-ads -> CO2. The calculated energy barriers of the first step are 15.8 and 12.4 kcal mol(-1) for N- and P graphene, respectively. The second step of the oxidation reaction on N- graphene proceeds with an energy barrier of about 4 kcal mol(-1). It is noteworthy that this reaction step was not observed on P-graphene because of the strong binding of O-ads species on the P atoms. Thus, it can be concluded that low-cost N-graphene can be used as a promising green catalyst for low-temperature CO oxidation.