Complexing-Coprecipitation Method to Synthesize Catalysts of Cobalt, Nitrogen-Doped Carbon, and CeO₂ Nanosheets for Highly Efficient Oxygen Reduction

The oxygen reduction reaction (ORR) is the key cathode reaction in renewable-energy technologies. Developing highly efficient, low-cost, methanol-tolerant and durable ORR catalysts is highly needed. In this research, we reported a simple complexing-coprecipitation method to synthesize CeO₂ nanosheets encapsulated by a nitrogen-doped carbon (NC) layer with uniformly dispersed Co nanoparticles catalysts on the surface. In particular, the 0.5Co-NC-CeO₂ sample exhibits high ORR catalytic activity with an onset potential of 875 mV (vs. RHE), a diffusion-limited current density of 4.72 mA/cm² and a positive half-wave potential of 817 mV (vs RHE), while 20% Pt/C presents an onset potential of 934 mV (vs. RHE), a diffusion limited current density of 5.8 mA/cm² and half-wave potential of 850 mV (vs. RHE). In addition, the catalyst 0.5Co-NC-CeO₂ also possesses a robust durability, that is the half-wave potential exhibits a negative shift of only 17 mV after 1000 cycles. The enhanced ORR performance can be attributed to the synergistic effect among Co, the nitrogen-doped carbon layer and CeO₂. The results demonstrated here have implications in designing non-Pt ORR catalysts. © 2019 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim