Past research showed that sintering and coking can be inhibited by growing porous overcoatings on nanometer catalyst particles , but this approach partially blocks the catalytic sites, limiting efficiency . For sub-nano Pt clusters deposited on SiO2 supports, we showed that even a single layer of overcoating completely blocked all Pt sites, rendering the clusters inert . Another strategy is to periodically regenerate catalysts by oxidizing away carbon deposits at high temperatures, however that would tend to deactivate sub-nano clusters by sintering . Alloying sub-nano clusters to modify the chemical and thermal properties is another approach; for example, alloying oxide-supported Pt cluster catalysts with tin or boron prevents carbon deposition and inhibits sintering , albeit at the cost of losing a substantial fraction of the catalytically active Pt sites.