Tuning the electronic structure of GaN monolayer by the single-atom promotor for hydrogenation of CO2

The efficient and cost-effective conversion of captured CO2 into valuable chemicals has garnered significant attention, driving the exploration of catalysts for CO2 capture and conversion. Here, we investigated a series of GaN monolayers with single metal atoms (M@GaN, M = Cr, Mn, Fe, Co, Ni, Cu, Zn, Al, and In) using first-principles calculations and ab initio molecular dynamics (AIMD) simulations. We propose a novel approach to enhance CO2 activation performance by tuning the single atom promotor (SAP). Compared to pristine GaN sheet, Ni@GaN, Cu@GaN, and Zn@GaN are predicted to have higher activity for CO2 adsorption and activation, in which the CO2 chemisorption process is predicted to be exothermic (−0.36 to −0.46 eV) with the low barrier (0.21–0.28 eV). This improvement can be attributed to occupied electronic states near the Fermi level in the N atom connected to SAP in the M@GaN (M = Ni, Cu, and Zn), enabling a better match with the LUMO level of CO2. In addition, compared with the AlN monolayer with better CO2 capture capability, Ni@GaN, and Zn@GaN exhibit considerable promise as catalysts for the hydrogenation of CO2 to HCOOH.