An Efficient Trifunctional Electrocatalyst for High-Current-Density Overall Water Splitting Self-Driven by Zinc–Air Batteries: Synergistic Enhancement through Hierarchical Structure Design and Cerium Oxide Coating

With the continuous development of new energy technologies, there is a growing need for highly efficient, economical, and robust trifunctional electrocatalysts for the hydrogen evolution reaction (HER), oxygen evolution reaction (OER), and oxygen reduction reaction (ORR) to meet the demanding requirements of applications, such as rechargeable zinc-air batteries (ZABs) and overall water splitting, particularly under high current conditions. Unfortunately, most current research on trifunctional catalysts is limited to water electrolysis at low current densities, which restricts their practical application. To address this issue, in this work, through an integrated multistage structural design combined with a cerium oxide coating, we have developed a trifunctional catalyst capable of efficient overall water splitting at high current densities, with enhanced stability. The CoFe@CNT@CeO 2 /IF (Iron foam) catalyst exhibits a half-wave potential of 0.822 V for ORR. At a high current density of 500 mA·cm –2, it shows an HER overpotential of 314 mV, with stable electrochemical performance maintained for 90 h. The OER overpotential is 403 mV, with stable electrochemical performance sustained for 96 h. In addition, the assembled ZAB demonstrates a power density of 135.75 mW·cm –2, and self-driven overall water splitting is successfully realized using this catalyst. These results demonstrate that the prepared trifunctional catalyst holds significant promise for energy storage and conversion applications.