The　long-range　ordered　lattice　structure　and　interconnected　porous　microstructure　of　porous　single　crystals　(PSCs)　provide　structural　regularity　and　connectivity　in　remote　electron　movement　to　stabilize　oxygen　vacancies　and　activate　lattice　oxygen　linked　to　surface　active　sites.　In　this　work,　we　prepare　NiO　powder,　single-crystal　(SC)　NiO,　and　PSC　NiO.　NiO　contains　a　significant　amount　of　oxygen　vacancies.　We　find　that　the　structure　of　porous　NiO　can　create　more　oxygen　vacancies.　We　load　Pt　onto　these　NiO　crystals　by　atomic　layer　deposition　(ALD)　to　activate　lattice　oxygen　on　definite　NiO　surfaces.　The　results　show　that　Pt-loaded　NiO　effectively　exhibits　CO　oxidation　performance,　in　which　Pt-loaded　PSC　NiO　completely　oxidizes　CO　at　65　°C.　With　1%　CO　fully　adsorbed,　the　density　of　activate　lattice　oxygen　becomes　an　essential　factor　affecting　performance.　PSC　NiO　with　deposited　Pt　clusters　exhibited　stable　CO　oxidation　catalysis　when　run　in　air　at　~65　°C　for　300　h.　©　2024　by　the　authors.