Orbital-Engineered Sn/RuO ₂ Nanocatalyst with Self-Regulating Electron Configuration for Durable Chlorine Evolution at Industrial Current Densities

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 RuO 2 through tin (Sn) doping. The resulting Sn/RuO 2 nanocatalyst achieves exceptional stability over 800 h at an industrial current density of 1 A cm –2, significantly surpassing RuO 2 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.