Spin-related symmetry breaking induced by half-disordered hybridization in Bi _xEr _2-xRu ₂O ₇ pyrochlores for acidic oxygen evolution

Abstract

While acidic oxygen evolution reaction plays a critical role in electrochemical energy conversion devices, the sluggish reaction kinetics and poor stability in acidic electrolyte challenges materials development. Unlike traditional nano-structuring approaches, this work focuses on the structural symmetry breaking to rearrange spin electron occupation and optimize spin-dependent orbital interaction to alter charge transfer between catalysts and reactants. Herein, we propose an atomic half-disordering strategy in multistage-hybridized Bi _xEr _2-xRu ₂O ₇ pyrochlores to reconfigure orbital degeneracy and spin-related electron occupation. This strategy involves controlling the bonding interaction of Bi-6 s lone pair electrons, in which partial atom rearrangement makes the active sites transform into asymmetric high-spin states from symmetric low-spin states. As a result, the half-disordered Bi _xEr _2-xRu ₂O ₇ pyrochlores demonstrate an overpotential of ~0.18 V at 10 mA cm ⁻² accompanied with excellent stability of 100 h in acidic electrolyte. Our findings not only provide a strategy for designing atom-disorder-related catalysts, but also provides a deeper understanding of the spin-related acidic oxygen evolution reaction kinetics.

Abstract

While water electrolysis offers a potential path for renewable hydrogen fuel, water oxidation electrocatalysts typically suffer from poor stabilities in acid. Here, authors prepare ruthenium-based pyrochlores and demonstrate promising activities and durabilities for acidic water electro-oxidation.