Synergistic t_2g-to-π* Electron Transfer and Nanotube Engineering in Spinal Catalysts for Ultra-Efficient Chloride...

Facing the massive energy consumption of over 200 TWh y^-1 of chlor-alkali industry, developing high-activity and durable non-precious CER (chlorine evolution reaction) catalysts is urgently needed to address the high overpotentials and suppress the dissolution high-valance metal species. Herein, a carbon quantum dots functionalized trimetallic Fe/Co/Ni spinel oxide nanotube architecture (FCNO@CQDs) is constructed, featuring t_2g-to-π* π-backbonding for dramatically enhanced CER activity and stability. The reverse electron flow from Co d-obritals to the vacant CQDs' π* orbitals can upshift the d-band center for enhanced intermediate adsorption, while stabilizing high-valent Co centers via increased bond order. Meanwhile, the open nanotube architecture facilitates rapid mass transfer and efficient Cl₂ desorption, validated by fluid dynamics simulations and in situ microscopic analysis. Electrochemically, FCNO@CQDs achieves an ultralow overpotential of 174 mV at 500 mA cm^-2 and exceptional selectivity of 98.8%-99.7% across a broad potential range, outperforming commercial Ru/Ir-based dimensionally stable anodes (DSA). Mechanistic studies reveal a dynamic transition from the Volmer-Heyrovský pathway to a hybrid Volmer-Heyrovský and Tafel mechanism under high Cl* coverage (θ_Cl ∼72%), enabling rapid kinetics. By bridging molecular orbital theory with nanoscale architecture design, FCNO@CQDs provides a valuable strategy for optimizing cost-effective, high-performance CER catalysts.