Tuning the lattice strain through manipulating crystal structure of high entropy oxides enhances electrocatalytic performance

Coskuner A. B., ERDİL T., ÖZGÜR Ç., Geyikci U., TOPARLI Ç.

Materials Research Bulletin, vol.186, 2025 (SCI-Expanded, Scopus) identifier

  • Publication Type: Article / Article
  • Volume: 186
  • Publication Date: 2025
  • Doi Number: 10.1016/j.materresbull.2025.113333
  • Journal Name: Materials Research Bulletin
  • Journal Indexes: Science Citation Index Expanded (SCI-EXPANDED), Scopus, Academic Search Premier, Chemical Abstracts Core, Chimica, Compendex, INSPEC
  • Keywords: Crystal structure, Electrocatalytic performance, High entropy oxide, Oxygen evolution/reduction reactions, Rechargeable zinc-air battery
  • Middle East Technical University Affiliated: Yes

Abstract

This study investigated the effects of crystal structure on the electrocatalytic OER and ORR performance. High-entropy oxides were synthesized, yielding rock-salt (HRS) and spinel cubic (HSP) crystal structures. Overpotentials for OER at a current density of 10 mA cm−2 were calculated as 311 mV and 357 mV for HRS and HSP, respectively. The zinc-air battery (ZAB) with HRS operated for about 180 h without degradation, while the ZAB with HSP lasted only 60 h. The stability difference between HRS and HSP might be attributed to the additional enthalpic contribution of lattice strain to configurational entropy, which might be much higher for HRS. Using the Williamson-Hall method, HRS has a significantly larger inhomogeneous lattice strain than HSP in the case of holding cationic sites with metals of Co, Cr, Cu, Ni, and Al due to its crystal structure. Thus, HRS is expected to have higher entropy than HSP.