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 Au-1/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. Au-8/mono-LDHs exhibited the best performance for CO2 adsorption. The adsorption energy of Au-8/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.