A novel composite catalyst (CoFeP@C) was constructed by high-quality CoFeP nanoparticles embedded in a N, P dual-doped carbon matrix. These CoFeP nanoparticles are rich in active sites of the oxygen evolution reaction (OER) at surfaces and provide metallic conductivity in their bulk phases. The N, P dual-doped carbon matrix provided abundant active sites of the oxygen reduction reaction (ORR) and formed a conductive network substrate. The ideal composite structure endowed CoFeP@C with highly efficient bifunctional performance for catalyzing both OER and ORR, accordingly making CoFeP@C an ideal catalyst for rechargeable Zn-air batteries. The liquid Zn-air battery of CoFeP@C has achieved a large power density of 143.5 mW/cm2 and can be charged and discharged stably for 200 h (1200 cycles). The solid-state Zn-air battery of CoFeP@C has achieved a power density of 72.6 mW/cm2 and can stably run for 20 h. This work has deepened the understanding of synergistic catalysis and paved one way for the development of high-performance bifunctional catalysts.
Keywords: bifunctional catalyst; metal phosphide; oxygen evolution reaction; oxygen reduction reaction; rechargeable Zn−air battery.