Mechanistic insights into CO2 activation on pristine, vacancy-containing and doped goldene: a single-atom layer of gold†

Goldene, a one-atom-thick gold sheet, is an emerging graphene-like flat 2-dimensional material. In this study, the geometrical and electronic properties, as well as CO₂ adsorption characteristics, of the pristine, vacancy-containing, and X-doped (X = Al, B, S, P and N) goldene sheets have been investigated by employing first-principles calculations based on the density functional theory. The distribution of energy levels and interaction between the CO₂ molecule and goldene (pristine, partially vacant, and doped) is discussed through the projected density of states (PDOS), electronic band structure (EBS), and Bader charge analysis. We found that CO₂ adsorbs physically on pristine goldene (PG) with an adsorption energy of −24.6 kJ mol⁻¹, while the creation of a mono-vacancy (MG), di-vacancy (DG) or tri-vacancy (TG) results in only marginal increases in the binding strength of CO₂ with the goldene, and the nature of the interaction remains physisorption. The calculated adsorption energies of CO₂ at MG, DG and TG are −25.60, −25.10, and −30.90 kJ mol⁻¹ respectively. Among a range of dopants considered in this work, doping by boron and nitrogen atoms causes goldene to absorb CO₂ chemically, with relatively large adsorption energies of −138.9 and −163.7 kJ mol⁻¹ and Bader charge transfers of −1.22 e⁻ and 0.66 e⁻ respectively. Our findings provide an in-depth understanding of the electronic properties of pure, vacancy-containing, and doped goldene, which can aid their potential application in CO₂ activation and conversion.