Work

Biradical-mediated synergistic electrocatalysis using metal-free redox molecular catalysts

Year: 2025

Type: article

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% H2O2 selectivity, 96.8% Faradaic efficiency, 2.21 mol g⁻¹cat h⁻¹ productivity) and three-electron nitric oxide reduction (NH₂OH as major product, 87.2% Faradaic efficiency, 1.68 mol g-¹cat h-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. Nature’s redox enzymes inspire the design of catalysts with precise spatial control. Here, the authors report stable metal-free bicarbenium catalysts that form biradicals for highly selective oxygen and nitric oxide reduction, revealing a blueprint for open-shell electrocatalysis.

Source: Nature Communications

DOI: 10.1038/s41467-025-66495-0