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Graphene aerogel keeps single-atom catalysts stable

Unconventional support material firmly anchors active species, prevents agglomeration

by Mitch Jacoby
August 11, 2019 | A version of this story appeared in Volume 97, Issue 32


To get the most out of precious metals used as industrial catalysts, researchers try to disperse the metals as finely as possible on a support material. The smaller the particle, the larger the fraction of atoms that reside at the surface, where they are exposed and available to convert reactants to products. But tiny particles tend to be unstable. Under reaction conditions, they fuse with nearby particles, covering would-be active sites and thwarting efforts to maximize efficiency and cut costs. The same holds for single-atom catalysts. One way to keep the atoms or particles isolated is to put very few of them on the support, but that leads to relatively inactive catalysts. Uğur Ünal and Alper Uzun of Koç University and their coworkers in the US may have come up with a way around that limitation. The researchers report that an easy-to-make, inexpensive graphene aerogel support firmly anchors high concentrations of catalytic iridium species containing a single metal atom. Other groups previously found that single-atom catalysts coalesced if their concentration on standard metal-oxide supports exceeded just a few percent. In contrast, the Koç team boosted the iridium loading to about 15% by weight and showed via spectroscopy and microscopy that every metal atom was isolated and catalytically active (ACS Catal. 2019, DOI: 10.1021/acscatal.9b02231).


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