Low-temperature synthesis of PdO-CeO2/C toward efficient oxygen reduction reaction

Abstract PdO-CeO2 nanocomposites have many potential (electro) catalytic applications, but are routinely synthesized at a high temperature. Herein, we report low-temperature synthesis of uniform PdO nanoparticles decorated by nearly amorphous CeO2 supported on carbon (PdO-CeO2/C). Unlike previous chemical oxidation of Pd to PdO at 500 oC, Pd is eletrochemically oxidized to PdO paired with CeO2/CeO2-x at 250 oC. To the best of our knowledge, the synthesis of PdO at such a low temperature has not been reported prior to this study. Compared with commercial Pt/C, PdO-CeO2/C exhibits an excellent oxygen reduction reaction (ORR) activity in alkaline media in terms of a remarkable mass activity (MA) of 1103 mA mgPd-1 (at 0.9 V vs. RHE), which is 5.9 times of that of commercial Pt/C. Density functional theory (DFT) suggests that the high ORR activity may arise from an appropriate oxygen adsorption strength at the interface of PdO-CeO2. Additionally, after 4000 cycles of accelerated durability test (ADT), the MA of the PdO-CeO2/C only decreases 13.4% superior to commercial Pt/C with a loss of 55.5%. The significantly enhanced durability should be correlated to the strong interfacial interaction between PdO and CeO2, which well anchors PdO and suppresses the migration of PdO to form large aggregates.