Platinum　(Pt)　and　Pt-based　alloys　have　been　extensively　studied　as　efficient　catalysts　for　both　the　anode　and　cathode　of　direct　methanol　fuel　cells　(DMFC).　Defect　engineering　has　been　revealed　to　be　practicable　in　tuning　the　charge　transfer　between　Pt　and　transition　metals/supports,　which　leads　to　the　charge　density　rearrangement　and　facilitates　the　electrocatalytic　performance.　Herein,　Pr-doped　CeO2　nanocubes　were　used　as　the　noncarbon　support　of　a　PtCu　catalyst.　The　concentration　and　structure　of　oxygen　vacancy　(Vo)　defects　were　engineered　by　Pr　doping.　Besides　the　Vo　monomer,　the　oxygen　vacancy　with　a　linear　structure　is　also　observed,　leading　to　the　one-dimensional　PtCu.　The　Vo　concentration　shows　the　volcanic　scenario　as　Pr　increased.　Accordingly,　the　activities　of　PtCu/PrxCe1-xO2　toward　methanol　oxidation　and　oxygen　reduction　reactions　exhibit　the　volcanic　scenario.　PtCu/Pr0.15Ce0.85O2　exhibits　the　optimal　catalytic　performance　with　the　specific　activity　3.57　times　higher　than　that　of　Pt/C　toward　MOR　and　1.34　times　higher　toward　ORR.　The　MOR　and　ORR　mass　activities　of　PtCu/Pr0.15Ce0.85O2　reached　1.05　and　0.12　A·mg-1,　which　are　3.09　and　0.92　times　the　values　of　Pt/C,　respectively.　The　abundant　Vo　afforded　surplus　electrons,　which　tailored　the　electron　transfer　between　PtCu　and　PrxCe1-xO2,　leading　to　enhanced　catalytic　performance　of　PtCu/PrxCe1-xO2.　DFT　calculations　on　PtCu/Pr0.15Ce0.85O2　revealed　that　Pr　doping　reduced　the　band　gap　of　CeO2　and　lowered　the　overpotential.　©　2023　American　Chemical　Society.