First principle study of the interaction of elemental Hg with small neutral, anionic and cationic Pd n (n = 1‒6) clusters

Abstract

Density functional theory (DFT)-based calculations have been performed so as to study the interaction of elemental mercury (Hg) with small neutral, cationic and anionic palladium clusters (Pd n , n = 1-6). Results of these calculations clearly indicate that frontier molecular orbital (FMO) theory is a useful method to predict the selectivity of Hg adsorption. Binding energies of Hg on cationic Pd n clusters are generally found to be greater than those on neutral and anionic clusters. Results of natural bond orbital (NBO) analysis show that the flow of electrons in the neutral and charged complexes is mainly due to s orbitals of Hg. NBO analysis also indicates that, in most of the cases, the binding energies of Hg with Pd n clusters are directly proportional to charge transfer, i.e., greater the charge transfer, higher is the binding energy.

Tuning the Adsorption of Elemental Mercury by Small Gas-Phase Palladium Clusters: First-Principles Study

“…These two new isomers have 0.04 and 0.67 eV energies higher than the most stable geometry. Hg BE in Bridge1 isomer (−0.46 eV) agrees well with the ealier study (−0.463 eV), which however reported this isomer to be the lowest-energy structure of HgPd 5 . The same study did not reveal any information about an isomer with hollow geometry for HgPd 5 .…”

“…However, there is no information about the threefold adsorption geometry of HgPd 3 complex in an earlier report. 38 B3LYP results predict the lowest-energy structure of HgPd 4 to be in top adsorption (M = 3) with slightly higher energy of 0.009 eV for the hollow adsorption geometry (M = 3). M06-L level calculation shows that bridge adsorption of Hg in triplet state is favored in Pd 4 cluster, which is followed by the hollow adsorption structure (M = 3) with only 0.03 eV higher in energy.…”

“…Despite the thrust in designing efficient Hg removal catalysts/ sorbents and the availability of evidence in support of Pd in this respect, research attention has not been focused on the Hg adsorption behavior on pure/alloy clusters of Pd on suitable support. In fact, to the best of our knowledge, there is so far only one study, reported by Siddiqui and Bouarissa, 38 on the interaction of elemental Hg with some small gas-phase Pd n (n = 1−6) clusters in neutral, cationic, and anionic states. In the present study, DFT was used to study the nature of binding of Hg atom on gas-phase small neutral Pd n (n = 1−6) clusters.…”

Simultaneous catalytic oxidation of elemental mercury and arsine over CeO2(111) surface: A density functional theory study

“…Currently, the main methods of Hg 0 and AsH 3 removal involve adsorption and catalytic oxidation [12]. In particular, noble metal catalysts, such as Au [13], Ag [14], Pd [15,16], Pt [17], Ru [18], and Ir [19], have excellent catalytic activity. These materials have, thus, been used as adsorbents and catalysts to remove Hg 0 and AsH 3 .…”

“…However, the high cost of noble metals has limited their commercialization and application. Fortunately, noble-metal-modi ed carbon materials, which are signi cantly cheaper than pure noble metals, also show catalytic effects [19,20]. In addition, single or binary metal oxides, especially transition metal oxides, other modi ed carbon materials, zeolites, and molecular sieves have been reported to show high Hg 0 and AsH 3 removal e ciencies [21][22][23][24].…”