The oxygen reduction reaction (ORR) is important in devices such as metal-air batteries and fuel
cells that can be involved in the transition to sustainable energies. The reaction suffers from sluggish kinetics, so the discovery of high-performance electrocatalysts an interesting research target. For example, metastable phases such as low-temperature or interfacial structures that are difficult to access in bulk may offer catalytically active surfaces.

Minghui Yang, Dalian University of Technology, China, and colleagues have found that the suboxide Zr₃O, which is formed at Zr-ZrO₂ interfaces but does not appear in the experimental Zr-O phase diagram, has a very good oxygen reduction reaction (ORR) performance, surpassing that of a benchmark Pt/C catalyst and most transition-metal-based catalysts.

The team used a solution precursor method to prepare Zr₃O on nitrogen-doped carbon (NC) and related nanoparticle catalysts. The addition of Fe₃C nanoparticles, for example, gave a Zr-Zr₃O-Fe₃C/NC catalyst with outstanding activity and durability that is based on inexpensive metals. A zinc-air battery (ZAB) using this cathode material showed a high power density of 241.1 mW cm^–2 and remained stable for over 50 days of continuous cycling. This demonstrates its potential for practical applications. Overall, the work demonstrates that interfacial or other phases that are difficult to stabilize may be useful in the discovery of high-performance electrocatalysts.

• Electrocatalytic Oxygen Reduction Using Metastable Zirconium Suboxide,
  Huashuai Hu, Zhihang Xu, Zhaorui Zhang, Xiaohui Yan, Ye Zhu, J. Paul Attfield, Minghui Yang,
  Angew. Chem. Int. Ed. 2024.
  https://doi.org/10.1002/anie.202404374