Synthesis of Ag-Ni-Fe-P Multielemental Nanoparticles as Bifunctional Oxygen Reduction/Evolution Reaction Electrocatalysts.

Multielemental nanoparticles (MENPs) provide the possibility to integrate multiple catalytic functions from different elements into one nanoparticle. However, it is difficult to synthesize Ag-based MENPs with transition metals such as Ni and Fe because of the strong phase segregation between Ag and the other metals. Here, we show that nonmetal element P can help the amalgamation of Ag with other metals. Ag-Ni-Fe-P MENPs are successfully synthesized by a solution-phase chemistry, and they demonstrate excellent bifunctional oxygen reduction reaction (ORR)/oxygen evolution reaction (OER) catalytic activities (the potential gap of the potential at 10 mA·cm-2 for OER and half-wave potential for ORR is 630 mV). More important, the synergistic effect from the MENPs endows them with even higher ORR or OER activity than the Ag or NiFeP nanoparticles. A rechargeable Zn-air battery is fabricated by using the Ag-Ni-Fe-P MENPs as the air electrode. The battery has an energy efficiency of ∼60% at 10 mA cm-2. Its performance is almost unchanged during a working period of 250 h, surpassing the Pt/C+IrO2-based battery. These results suggest that the rationally designed MENPs can integrate multiple catalytic functions together and achieve a synergistic effect, which can be used as high-performance multifunctional catalysts.