Anthropogenic　ammonia　emissions　present　significant　environmental　and　human　health　risks,　while　they　can　be　effectively　purified　by　selective　catalytic　oxidation　employing　high-performance　catalysts.　Herein,　cost-effective　Fe-Ce　composite　oxide　catalysts　featuring　tailored　phase　structures　were　constructed　via　a　facile　one-step　sol–gel　approach.　The　rational　tuning　of　Fe　content　led　to　the　formation　of　well-crystallized　CeO2-like　solid　solution　and　poorly　crystallized　surface　Fe2O3.　The　coexistence　of　these　two　phases,　coupled　with　the　electron　transfer　at　their　interface,　gave　rise　to　abundant　oxygen　vacancies.　These　vacancies　generated　additional　Lewis　acid　sites　(Fe2+　and　Ce3+),　thereby　facilitating　the　adsorption　of　NH3.　Simultaneously,　they　enhanced　lattice　oxygen　mobility　and　increased　active　surface　oxygen　species　to　accelerate　the　oxidation　of　NH3　through　both　i-SCR　and　imide　mechanisms.　Consequently,　superior　catalytic　activity,　high　N2　selectivity,　and　robust　stability　were　achieved　on　the　optimized　Fe-Ce　composite　oxide　under　demanding　conditions.　The　strategy　of　regulating　the　synergy　between　solid　solutions　and　surface　oxides　can　be　extended　to　construct　other　efficient　and　stable　composite　oxides　for　pollutant　elimination.　©　2025　Elsevier　B.V.