Boosting the thermal stability and catalytic performance by confining Ag single atom sites over antimony-doped tin oxide via atom trapping

Catalysts based on single atoms of noble metals have attracted much research interest. However, single atoms are mobile and prone to sintering (forming large clusters) under reaction conditions, especially at elevated temperatures. Driven by the long-standing interest in the development of thermally stable catalysts, there is an urgent demand for synthesizing sintering-resistant single-atom catalysts. Here, we report a high-temperature self-assembly route to fabricate thermally stable silver (Ag) single-atom catalysts by confining Ag single atom sites over antimony-doped tin oxide (ATO) via atom trapping at 800 °C in air. Unique self-dispersion of Ag species takes place over the ATO support after high-temperature aging, contrary to a tendency of sintering or coalescence. Extended X-ray absorption fine structure (EXAFS) analysis confirms the presence of predominantly high dispersed isolated Ag species in Ag/ATO-800 °C aged sample. CO oxidation tests reveal that the stable single-atom Ag-on-ATO catalyst shows negligible decay and even a slight increase in experimentally observed activity after 800 °C aging. In contrast, the high temperature aging treatment causes serious catalyst deactivation, as expected for conventional Al₂O₃ supported noble metal catalyst. Our finding paves the way for using commercially available support to disperse and stabilize noble metal single atoms via atom trapping for the automotive CO oxidation reaction.