Mott–Schottky Heterojunction on Self-Supporting TiO ₂ Nanotubes Enables Efficient and Stable Chlorine Evolution Reaction

Chlorine evolution reaction (CER), pivotal for modern chemical manufacturing, remains hindered by catalyst deactivation and competitive oxygen evolution reaction. To address these, a Mott-Schottky heterojunction electrocatalyst was demonstrated via in situ growth of Ru-RuO₂ nanoparticles on TiO₂ nanotubes (NTs). The difference of work functions renders electron spontaneous migration at the heterojunction interface, generating a built-in electric field and upshifting the d-band center of the catalyst, which optimizes the adsorption to key intermediates and strengthens catalyst-support interaction. The resultant self-supporting Ru-RuO₂/TiO₂ NTs electrode exhibits excellent CER performance with low overpotential of 43 mV at 50 mA cm^-2. Crucially, the electrode demonstrates 95.8% Cl₂ selectivity and stable operation over 600 h at 100 mA cm^-2, significantly surpassing Ru-RuO₂/Ti plate (selectivity: 87.7%, stability: ∼70 h) and dimensionally stable anode (selectivity: 84.8%, stability: ∼100 h). This work demonstrates a feasible pathway to design efficient CER self-supporting catalysts for the chlor-alkali industry and environmental protection.