Spinel oxide electrocatalysts under ML scrutiny: Orb v3 symmetry collapse and ALIGNN prediction failures in Co-based OER spinels
Baek, Hamkins, Li et al. showed in Nature Communications that introducing site-selective cations (Zn, Ga, Mg, Al) into Co–Fe–Cr–Mn–Ni high-entropy spinel oxide (HESO) modulates cation Td/Oh occupancy. Zn preferentially occupies tetrahedral sites — DFT confirms a 1.155–1.360 eV Td preference — driving Co³⁺ into octahedral sites that are the active centers for oxygen evolution. Zn-HESO achieves η₁₀ = 295 mV with a Tafel slope of 25 mV/dec, making it one of the better OER catalysts in the high-entropy oxide family.