Size effect of CO2 adsorption onto Au cluster-functionalized monolayer ZnAl layered double hydroxides: Insights from first-principles computations

CO₂ capture technology can effectively reduce the concentration of greenhouse gas in the atmosphere and purify the exhausts in fuel engines. Monolayer layered double hydroxides (LDHs) has a large specific surface area and may have excellent ability to capture CO₂. In this paper, structure, electronic properties and capacity of two-dimensional monolayer ZnAl layered double hydroxides (mono-LDHs) with supported gold clusters Au_n (n = 1,2,3,4,5,8,10,13) for CO₂ capture were investigated by density functional theory (DFT). The results show that Au₁/mono-LDHs has the best structural stability due to the biggest binding energy. When the size of the supporting Au_n cluster increased, the ability of Au_n/mono-LDHs to adsorb CO₂ is increased first then decreased quickly. Au₈/mono-LDHs exhibited the best performance for CO₂ adsorption. The adsorption energy of Au₈/mono-LDHs reaches -2.31 eV, which is 10 times greater than that of mono-LDHs. Our work manifests that size-dependent effect between the ability of mono-LDHs on CO₂ capture and Au_n clusters, and open new avenues for designing Au cluster loaded two-dimensional monolayer layered double hydroxides.