Diborane Interactions with Pt₇/Alumina: Preparation of Size-Controlled Borated Pt Model Catalysts

Abstract

Bimetallic catalysts provide the ability to tune catalytic activity, selectivity, and stability. Model catalysts with size-selected bimetallic clusters on well-defined supports offer a useful platform for studying catalytic mechanisms, however, producing size-selected bimetallic clusters can be challenging. In this study, we present a way to prepare bimetallic model (Pt n B m /alumina) cluster catalysts by depositing size-selected Pt 7 clusters on an alumina thin film, then selectively adding boron by exposure to diborane and heating. The interactions between Pt 7 /alumina and diborane were probed using temperature-programmed desorption/reaction (TPD/R), X-ray photoelectron spectroscopy (XPS), low energy ion scattering (ISS), plane wave density functional theory (PW-DFT), and molecular dynamic (MD) simulations. It was found that the diborane exposure/heating process does result in preferential binding of B in association with the Pt clusters. Borated Pt clusters are of interest because they are known to exhibit reduced affinity to carbon deposition 1 in catalytic dehydrogenation. At high temperatures, theory, in agreement with experiment, shows that boron tends to migrate to sites beneath the Pt clusters forming Pt-B-O suf bonds that anchor the clusters to the alumina support.

Advanced XPS characterization: XPS-based multi-technique analyses for comprehensive understanding of functional materials

“…Comparisons of these changing ISS ratios with CO TPDs led to the conclusion that low temperature CO desorption in the TPD was due to CO adsorbed onto Pd-TiO 2 peripheral sites, rather than directly on-top of Pd clusters. A similar experimental procedure has been used to study other Pd cluster/metal oxide systems 172,173 as well as the relationships between Pt cluster sizes and ethylene 227 and diborane 228 surface reactions.…”

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.…”

Moving Mountains: Reshaping the Activity Volcano of Electrocatalysis with Fluxional Subnano Clusters

“…One approach to mitigate sintering is to use a conductive substrate with appropriate anchoring sites, such as graphdiyne, black phosphorous, nanocarbon with engineered defects, and conducting metal oxides. [22][23][24] While stronger cluster-support interaction will reshape the PES of the cluster and affect the cluster-support charge transfer, [25][26][27] we expect the trends across fluxional clusters toward increased activity of more weakly binding metals to hold true, because fluxionality is characteristic of clusters also on more strongly binding surfaces.…”