Orbital-Engineered Sn/RuO₂ Nanocatalyst with Self-Regulating Electron Configuration for Durable Chlorine Evolution at...

Chlorine evolution reaction (CER) is a critical electrochemical process in the chlor-alkali industry and water treatment, yet conventional ruthenium (Ru)-based electrodes suffer from severe structural instability under operating conditions. This study proposes an orbital-engineered self-regulating strategy by tailoring the electronic configuration of RuO₂ through tin (Sn) doping. The resulting Sn/RuO₂ nanocatalyst achieves exceptional stability over 800 h at an industrial current density of 1 A cm^-2, significantly surpassing RuO₂ catalyst (∼100 h), while maintaining good activity and selectivity (97.9%). Both experimental and theoretical analyses reveal that the orbital hybridization improves p-d coupling between Ru 4d and Sn 5s/5p states by incorporating Sn. This specific orbital interaction triggers a concerted electron density redistribution, which weakens the Ru-O bond by modulating its π* orbital occupancy, lowering the energy barrier for chlorine intermediate adsorption, while simultaneously enhances the antibonding orbital of the Sn-O bond, strengthening its covalent character and effectively anchoring the lattice oxygen against anodic dissolution. The Ru-O-Sn bridge serves as an efficient electron feedback channel that establishes a favorable electronic structure for sustained catalysis, which suppresses Ru overoxidation and maintains stable electronic states throughout prolonged electrolysis. This work establishes an orbital engineering paradigm for designing high-performance nanocatalysts, demonstrating that deliberate modulation of electronic orbitals via strategic doping offers a practical route to simultaneously achieve high activity and exceptional durability under demanding industrial conditions.