A density functional theory (DFT) method was used to study the adsorption of Hg-0 on activated carbon supported Pd-n (n <= 38) clusters, the size and Cu modulation of Pd clusters were investigated. The adsorption energies of Hg-0 on Pd-n/AC (n = 4, 6, 8, 13, 19, 23) show that the strongest adsorption strength is on the Pd-13/AC. AC can prevent Pd clustering to a bulk and disperse cluster on the surface by comparing the interaction energy of Pd-n cluster on AC with the binding energy per atom of corresponding Pd-n cluster. Furthermore, some of Pd atoms in Pd-13 cluster were substituted by Cu atoms to improve the adsorption of Hg-0 and reduce the dosage of Pd. CuPd12, Cu2Pd11 and Cu6Pd7 are the most stable bimetallic clusters. In addition, the adsorption of Hg-0 shows that Cu2Pd11/AC is the most effective adsorbent for Hg-0. (C) 2016 Elsevier B.V. All rights reserved.