Trends in the CO oxidation and PROX performances of the platinum-group metals supported on ceria

•Ceria loaded with Pt, Pd, Ir, Rh, or Ru was synthesized by solution combustion.•The H2-free CO oxidation activity order is: Rh>Pd>Pt>Ru>Ir.•H2 promotes CO oxidation and the PROX activity order is: Pt>Pd>Rh>Ir>Ru.•This order is consistent with published CO+O activation energy trends from DFT.•CO oxidation competes with CO methanation on Rh and Ru catalysts above 200°C.