Conversion of CO₂and C₂H₆to propanoic acid on an iridium-modified graphene oxide surface: Quantum-chemical investigation

Using density-functional theory, we performed calculations on a single-atom catalyst (SAC) comprising an iridium atom on a modi fied graphene oxide (Ir₁-GO) surface to investigate the conversion of CO₂ and C₂H₆ molecules to propanoic acid. The great catalytic activity of this surface is due to the strong adsorption of C₂H₆ and CO₂ (-0.92 and -0.56 eV adsorption energies, respectively). First, C₂H₆ is dehydrogenated at an oxide site of the surface to form C₂H₅ + OH with a barrier of height 0.63 eV; the adsorbed CO₂ then reacts with ethyl to form C₂H₅COO or COOC₂H₅ with barriers of 0.95 and 1.70 eV, respectively. Less likely, the adsorbed CO₂ might be hydrogenated by hydroxyl to form HCOO or COOH, with energy barriers of 1.34 and 1.49 eV, respectively. We predict that the most likely path for the conversion of the adsorbed CO₂ and ethane molecules on the Ir₁-graphene oxide surface would involve the formation of propanoic acid (C₂H₅COOH). To understand the interaction between adsorbates and surfaces, we calculated and analyzed the local densities of states (LDOS) and the electron localization function (ELF).