Hydrangea Macrophylla-Like CeO₂ Coated by Nitrogen-Doped Carbon as Highly Efficient ORR Cathode Catalyst in a Hybrid Proton Battery

In this paper, nitrogen-doped carbon (NC) coated tens nanometer hydrangea macrophylla-like CeO₂(CeO₂-NC) was synthesized by simple hydrothermal and polymeric calcination approach. Samples are characterised by SEM, Raman spectroscopy, XPS, etc. CeO₂-NC shows an initial potential of 0.90V (vs. Ag/AgCl) in 9.5 M H₃PO₄. In addition, the CeO₂-NC composite also exhibits a high limiting current (6.25 mA mg⁻¹). CeO₂-NC effectively combines the high initial potential of CeO₂ with the high limiting current of NC. Moreover, a hybrid proton battery assembled with CeO₂-NC composite as the cathode catalyst and MoO₃ (1 mg) as anode catalyst can produce a high capacity of 261.7 mAh at 1 A g⁻¹. The hybrid battery also exhibits excellent catalytic stability. After 1000 cycles at a high current density of 15 A g⁻¹, the capacity of the battery still remains 125.0 mAh, with a retention rate of approximately 90.9%. The improvement in battery performance is due to the use of NC to coat CeO₂, which improves the limiting current and durability of the electrode. The presented hybrid proton batteries have further enriched the application of electrochemical energy storage devices, and the preliminary exploration of cathode catalysts significantly improved the catalytic performance of ORR under acidic conditions.