Bimetallic Ag‐Pt Sub‐nanometer Supported Clusters as Highly Efficient and Robust Oxidation Catalysts

Abstract

A combined experimental and theoretical investigation of Ag‐Pt sub‐nanometer clusters as heterogeneous catalysts in the CO→CO2 reaction (COox) is presented. Ag9Pt2 and Ag9Pt3 clusters are size‐selected in the gas phase, deposited on an ultrathin amorphous alumina support, and tested as catalysts experimentally under realistic conditions and by first‐principles simulations at realistic coverage. In situ GISAXS/TPRx demonstrates that the clusters do not sinter or deactivate even after prolonged exposure to reactants at high temperature, and present comparable, extremely high COox catalytic efficiency. Such high activity and stability are ascribed to a synergic role of Ag and Pt in ultranano‐aggregates, in which Pt anchors the clusters to the support and binds and activates two CO molecules, while Ag binds and activates O2, and Ag/Pt surface proximity disfavors poisoning by CO or oxidized species.

Magnetron-sputtered copper nanoparticles: lost in gas aggregation and found by in situ X-ray scattering

“…The method has acquired particular popularity as is evidenced by an increasing number of papers that have been published in recent years. Single-metal, [4][5][6][7][8][9][10][11][12][13][14][15] alloyed [16][17][18][19][20][21][22][23][24][25][26] and heterostructured NPs [27][28][29][30][31][32][33][34][35][36][37][38][39][40] have been successfully synthesized.…”

From Isolated Ions to Multilayer Functional Materials Using Ion Soft Landing

“…[66] Furthermore,e lectrochemical characterization of soft-landed clusters has been used to examine an unusual size dependence of the electrocatalytic conversion of CO 2 on Cu nanoclusters. [75] Thee lectrochemical activity of size-selected Pt clusters supported on glassy carbon electrodes for the ORR was examined as af unction of cluster coverage.Apronounced increase in the O 2 reduction current was observed at acritical edge-to-edge distance that was substantially greater than what could be accounted for by the increasing cluster coverage alone. [14,15,20] It follows that, over the last few years,u nexpected phenomena have started to present themselves at these high surface coverages of clusters.F or example,O stwald ripening is aw ell-known process by which the size distribution of clusters or nanoparticles evolves as smaller particles dissolve and the material is redeposited onto larger particles.…”

“…[74] These findings have substantial implications for the preparation of both catalytically active and stable surfaces. [75] Thee lectrochemical activity of size-selected Pt clusters supported on glassy carbon electrodes for the ORR was examined as af unction of cluster coverage.Apronounced increase in the O 2 reduction current was observed at acritical edge-to-edge distance that was substantially greater than what could be accounted for by the increasing cluster coverage alone. [76] This increased activity ( Figure 5) was attributed to overlap of the electric double layers in solution when neighboring clusters reached ac ritical separation (coverage).…”

Von isolierten Ionen zu mehrschichtigen funktionellen Materialien durch sanfte Landung von Ionen

“…[66] Weiterhin wurde über elektrochemische Charakterisierung von sanft gelandeten Clustern die ungewçhnliche Grçßenabhängigkeit von Kupfer-Nanoclustern bei der elektrokatalytischen CO 2 -Umsetzung untersucht. [75] Die elektrochemische Aktivitätv on grçßenselektierten Pt-Clustern, aufgetragen auf Glaskohlenstoff-Elektroden, in der ORR wurde als Funktion der Bedeckung untersucht. Oberflächen, die über SLI mit Clustern bestückt wurden, enthielten diese Cluster bis vor kurzem in geringem Bedeckungsgrad, um Wechselwirkungen zwischen den Clustern mçglichst gering zu halten.…”

“…[74] Diese Erkenntnisse haben wichtige Auswirkungen auf die Präparation stabiler katalytisch aktiver Oberflächen. [75] Die elektrochemische Aktivitätv on grçßenselektierten Pt-Clustern, aufgetragen auf Glaskohlenstoff-Elektroden, in der ORR wurde als Funktion der Bedeckung untersucht. Ein bedeutender Anstieg im O 2 -Reduktionsstrom wurde bei einem kritischen "Kante-zu-Kante"-Abstand beobachtet, der deutlich zu groß war,als dass er alleine auf die Zunahme der Bedeckung zurückgeführt werden konnte (Abbildung 5).…”