02005nas a2200169 4500008004100000022001400041245008700055210006900142260000900211300001400220490000800234520142600242100001701668700002601685700001601711856010801727 2014 eng d a1932-744700aEffect of silicon doping on the reactivity and catalytic activity of gold clusters0 aEffect of silicon doping on the reactivity and catalytic activit cAPR  a7501-75070 v1183 a

Doping is known to be an excellent and simple way of catalyst design. Although notable progress has been made in understanding the reactivity and catalytic activity of gas-phase and supported gold clusters, very few studies have been carried out on the doped gold clusters. In the present work, we have carried out density functional theory calculations to investigate the effect of silicon doping on the reactivity and catalytic activity of gold nanoclusters. The present work particularly focuses on the adsorption and activation of molecular oxygen on the pristine and silicon-doped gold clusters. The results confirm that the silicon-doped Au7Si cluster shows considerable binding and activation of the O-2 molecule in comparison to the pristine Au-8 cluster as reflected in the relevant geometrical parameters (O-O and Au-O bond lengths) and O-O stretching frequency. However, silicon doping has no contrasting effect on the reactivity and catalytic activity of the Au-7 cluster. In addition to the stronger binding and activation of the O-2 molecule, the doped Au7Si cluster leads to a significant reduction in the activation barrier (0.57 eV) for the environmentally important CO oxidation reaction in contrast to the catalytically inactive pristine Au-8 cluster (1.22 eV). Thus, our results highlight the critical role of doping foreign impurities for future endeavors in the field of gold nanocatalysis.

1 aManzoor, Dar1 aKrishnamurty, Sailaja1 aPal, Sourav uhttp://library.ncl.res.in/content/effect-silicon-doping-reactivity-and-catalytic-activity-gold-clusters01802nas a2200229 4500008004100000022001400041245009900055210006900154260011000223300001300333490000700346520091800353653002501271653003601296653001801332653001901350653002001369653002601389100001701415700001601432856012401448 2014 eng d a0376-471000aEnhanced interaction of molecular oxygen with amino acid complexes of silver and gold clusters0 aEnhanced interaction of molecular oxygen with amino acid complex aDR K S KRISHNAN MARG, PUSA CAMPUS, NEW DELHI 110 012, INDIAbNATL INST SCIENCE COMMUNICATION-NISCAIRcAUG a996-10000 v533 a

Density functional theory calculations have been carried out to study the effect of amino acid adsorption on the reactivity of silver and gold clusters with molecular oxygen. It is found that the amino acids glycine and alanine form stable complexes with both Ag-4 and Au-4 clusters. However, the extent of interaction is more in the case of the Au-4 cluster, as reflected from the increase in binding energy in the amino acid Au-4 complexes. Our results confirm that the adsorption of amino acids glycine and alanine enhances the reactivity of Ag-4 and Au-4 clusters towards O-2 molecule. The enhanced reactivity of O-2 molecule towards the amino acid metal cluster complexes is manifested by an increase in the O-2 binding energy and a decrease in the M-O (M = Ag, Au) bond length. Moreover, it is found that the co-adsorption of amino acids and O-2 molecule on the Ag-4 and Au-4 clusters is cooperative.

10aAmino acid complexes10aDensity functional calculations10aGold clusters10aMetal clusters10aSilver clusters10aTheoretical chemistry1 aManzoor, Dar1 aPal, Sourav uhttp://library.ncl.res.in/content/enhanced-interaction-molecular-oxygen-amino-acid-complexes-silver-and-gold-clusters-002378nas a2200169 4500008004100000022001400041245009500055210006900150260011000219300001400329490000700343520167300350100001702023700002602040700001602066856012602082 2016 eng d a1463-907600aEndohedrally doped gold nanocages: efficient catalysts for O-2 activation and CO oxidation0 aEndohedrally doped gold nanocages efficient catalysts for O2 act aTHOMAS GRAHAM HOUSE, SCIENCE PARK, MILTON RD, CAMBRIDGE CB4 0WF, CAMBS, ENGLANDbROYAL SOC CHEMISTRYcMAR a7068-70740 v183 a

Gold nanocages are the most attractive catalytic materials as all the atoms in the cage type clusters reside on the surface, making them available for chemisorption by reacting molecules. Due to a hollow space at the center, their chemical and catalytic properties can be tuned effectively and easily by endohedral doping. While a significant experimental and theoretical understanding is currently available on the structural and electronic properties of doped gold cages, very little information is available on their reactivity and catalytic behavior. In the present work, with the help of density functional theory calculations we demonstrate that endohedral doping leads to a notable increase in the binding energy of molecular oxygen on the gold nanocages. The enhancement in the O-2 binding energy on the doped gold cages is also confirmed by a significant decrease in the Au-O and an increase in the O-O bond lengths, corroborated by a red shift (similar to 250 cm(-1)) in the O-O stretching frequency as compared to the pristine cage. Furthermore, interestingly, the doped gold cages show very low activation barriers for the environmentally important CO oxidation reaction as compared to the pristine gold cage. Importantly, the decrease in the barrier height is comparatively greater for the rate limiting step of O-O-C-O intermediate formation and as a result the CO oxidation is expected to be more facile on the doped gold cages. Thus, the current study highlights the role of heteroatom doping in imparting new chemical and catalytic properties to gold cages and is expected to spur further research in the design of efficient gold nanocatalysts.

1 aManzoor, Dar1 aKrishnamurty, Sailaja1 aPal, Sourav uhttp://library.ncl.res.in/content/endohedrally-doped-gold-nanocages-efficient-catalysts-o-2-activation-and-co-oxidation-0