Ferromagnetic Surface Segregation via Stress-Concentration Coupling Boosts the Oxygen Evolution Reaction in RuO<sub>2</sub>.
basic_science · Level V
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- Record sourced from PubMed, PMID 40913587.
- Also identified by DOI 10.1021/acsnano.5c06052.
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Abstract
RuO<sub>2</sub>, the benchmark catalyst for the oxygen evolution reaction (OER), has traditionally been considered Pauli paramagnetic; however, recent findings have demonstrated its antiferromagnetic (AFM) properties, hinting at the opportunity to enhance RuO<sub>2</sub>'s OER performance by manipulating its magnetic traits. In this study, we successfully induced weak ferromagnetism in commercial RuO<sub>2</sub>, transitioning it from an AFM state using an electrochemical sodiation method. This process resulted in high activity, achieving an overpotential of 145 mV to reach 10 mA cm<sup>-2</sup> and extending the service hours by more than 13 times compared to pristine RuO<sub>2</sub> in 0.5 M H<sub>2</sub>SO<sub>4</sub>. A combination of experimental and theoretical analyses indicated that the sodiation triggers significant surface compressive stress, leading to lattice distortion and disruption of the pristine structural symmetry of RuO<sub>2</sub>. Consequently, orbital degeneration ensues, prompting individual spin-up <i>d</i> electrons to jump to the high-spin state. This mechanism drives the conversion from AFM to weak FM behavior for RuO<sub>2</sub>, ultimately yielding exceptional catalytic activity and stability.