Biradical-mediated synergistic electrocatalysis using metal-free redox molecular catalysts.
basic_science · Level V
Where this comes from
- Record sourced from PubMed, PMID 41390842.
- Also identified by DOI 10.1038/s41467-025-66495-0 and PMC identifier 12749437.
- Licence recorded as CC BY-NC-ND.
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Abstract
Nature's redox enzymes achieve remarkable selectivity by organizing active sites with precise spatial control, an ability difficult to replicate in synthetic systems. Inspired by this, we report a class of stable, metal-free bicarbenium-based molecular catalysts that undergo electrochemical two-electron reduction to form biradical intermediates. These biradicals are confined within a rigid xanthene bridge ( ~ 4.3 Å), creating a spatially defined pocket that engages paramagnetic substrates, such as O₂ and NO, resembling nature's synergistic catalysis. This biradical-mediated synergistic catalysis enables highly selective two-electron oxygen reduction (99.3% H<sub>2</sub>O<sub>2</sub> selectivity, 96.8% Faradaic efficiency, 2.21 mol g⁻¹<sub>cat</sub> h⁻¹ productivity) and three-electron nitric oxide reduction (NH₂OH as major product, 87.2% Faradaic efficiency, 1.68 mol g<sup>-</sup>¹<sub>cat</sub> h<sup>-</sup>¹ productivity). Experimental and computational studies confirm the sustained redox cycling, supported by favorable spin-pairing and substrate binding geometries, which enhance both catalytic selectivity and efficiency. This work presents a blueprint for pathway-specific, radical-mediated catalysis, offering new design principles for metal-free electrocatalytic platforms that exploit open-shell reactivity.