Copper-Palladium Tetrapods with Sharp Tips as a Superior Catalyst for the Oxygen Reduction Reaction

The development of superior non-Pt catalysts for the oxygen reduction reaction (ORR) is highly desirable but still challenging. Herein, we prepared 50-nm CuPd tetrapods with catalytic performance towards the alkaline ORR that was higher than that of Pd nanoparticles, CuPd nanoparticles, CuPd tetrahedrons, and 7-nm CuPd tetrapods. The mass activity of 50-nm CuPd tetrapods was 0.29AmgPd(-1), which was superior to that of commercial Pt/C and most Pd-based catalysts reported to date. Mechanistic studies revealed that the enhanced performance could be attributed to the synergy of the alloy effect and sharp-tip effect, both of which enable the accumulation of negative charges on the Pd atoms at the vertices of the tetrapods. The high negative charge density of the Pd atoms at the vertices lowers the Pd d-band center and, thus, its oxygen adsorption energy. This work provides a pathway to improve the activity of ORR catalysts by modulating their electronic structures, which opens up new sight to design promising non-Pt catalysts for the ORR.