Tuning surficial atomic configuration of Pt–Ir catalysts for efficient ammonia oxidation and low-temperature direct ammonia fuel cells

•Actual surface Pt/Ir atomic configurations in PtxIry/XC-72 catalysts are totally different by using XPS and HS-LEIS techniques.•The Pt species prefer to be segregated on the topmost surface of PtIr alloys.•The Pt favours the enhancement of current densities and the Ir facilitates reducing onset potentials in ammonia oxidation reaction.•The relationship between current density/onset potential and Pt/Ir atomic ratio were established.•The well-studied Pt5Ir5/XC-72 achieved a compelling peak power density (230.0 mW cm−2) in direct ammonia alkaline exchange membrane fuel cell.