Tuning　the　electronic　state　and　local　structure　of　single-atom　dispersed　metals　is　important　to　improve　the　performance　of　single-atom　catalysts.　Here,　we　find　that　the　electronic　structure　of　Pt　single　atoms　(Pt1)　depends　on　the　facets　of　CeO2.　Various　characterizations　and　density　functional　theory　calculations　demonstrate　that　Pt1　anchored　on　the　(110)　facet　of　CeO2　nanorods　exhibits　a　positively　charged　state,　while　it　approaches　the　metallic　state　on　the　(100)　facet　of　CeO2　nanocubes.　The　different　Pt1　states　on　these　facets　are　attributed　to　the　Pt-O-Ce　microstructures　with　different　electron　transfer　patterns.　The　positively　charged　Pt1　shows　much　weaker　adsorption　of　CO　which　is　favorable　for　its　complete　oxi-dation　at　lower　temperatures.　In　contrast,　the　metallic　Pt1　can　facilitate　the　activation　of　H2　in　the　form　of　dissociation.　The　activated　H　species　on　metallic　Pt1　then　promote　the　preferential　oxidation　of　CO　to　a　greater　extent　and　significantly　reduce　the　reaction　barrier.　This　study　provides　important　implications　for　tailoring　the　electronic　structure　of　single-atom　centers　for　heterogeneous　catalysis　by　bonding　to　specific　facet　supports.(c)　2022　Elsevier　Inc.　All　rights　reserved.