Oxidation of CO on a carbon-based material composed of nickel hydroxide and hydroxyl graphene oxide, (Ni₄(OH)₃-hGO) - A first-principles calculation

Nickel or nickel hydroxide clusters and graphene oxide (GO) composites are novel nanomaterials in the application of electrochemical catalysts. In this work, we calculated the energy of Ni₄ adsorbed onto saturated hydroxyl graphene oxide (hGO), which forms a Ni₄(OH)₃ cluster on the hydroxyl graphene oxide (Ni₄(OH)₃-hGO) and releases 4.47 eV (5.22 eV with DFT-D3 correction). We subsequently studied the oxidation of CO on the Ni₄(OH)₃-hGO system via three mechanisms - LH, ER and carbonated mechanisms. Our results show that the activation energy for oxidation of the first CO molecule according to the ER mechanism is 0.14 eV (0.12 eV with DFT-D3 correction), much smaller than that with LH (E_a = 0.65 eV, 0.61 eV with DFT-D3 correction) and with carbonated (E_a = 1.28 eV, 1.20 eV with DFT-D3 correction) mechanisms. The barrier to oxidation of the second CO molecule to CO₂ with the ER mechanism increases to 0.43 eV (0.37 eV with DFT-D3 correction), but still less than that via LH (E_a = 1.09 eV, 1.07 eV with DFT-D3 correction), indicating that CO could be effectively oxidized through the ER mechanism on the Ni₄(OH)₃/hGO catalyst.