Unpaired Electrons-Empowered Bridge-Site Lattice Oxygen for Efficient CO ₂ -to-CH ₄ Conversion via a CO ₂ /H ₂ Fuel Cell

CO₂/H₂ fuel cells represent a promising route for simultaneous CO₂ conversion and power generation, yet face efficiency limitations due to poor CO₂ activation. Effective reduction requires rapid electron transfer to CO₂'s lowest unoccupied molecular orbital, which conventional catalysts struggle to achieve. Herein, we design a RuO₂-based catalyst featuring abundant unpaired electrons that simultaneously enrich bridge-site lattice oxygen and metal centers. These electron enrichments enable efficient electron transfer to CO₂, significantly enhancing activation. In a CO₂/H₂ fuel cell, this catalyst achieves a CO₂ conversion rate of 1242.5 μmol gcat⁻¹ h⁻¹─18 times that of RuO₂/CNTs, while contributing 28.2% of electricity generation versus 1.5% for RuO₂/CNTs. In situ Raman spectroscopy reveals enhanced activation through B2g-mode vibrations under CO₂. Experimental and theoretical analyses verify orbital hybridization involving both Ru 3d and O 2p orbitals with CO₂'s π* orbitals, synergistically promoting adsorption. This work establishes a dual-site activation strategy for developing CO₂ reduction catalysts.