Rational surface Design and electron Regulation of co-deposition Ru and Ti on TiO₂ nanotubes as self-supporting electrode for high-performance chlorine evolution reaction

The chlorine evolution reaction (CER) is essential for chlorine (Cl₂) production. However, the catalyst deactivation and side reaction oxygen evolution reaction (OER) are still serious problems for CER. Improving the stability and selectivity of catalyst for long term electrocatalytic reaction in large current density is highly desired. In this work, a self-supporting Ti/RuO₂@TiO₂ nanotubes (NTs) electrode had been developed by co-sputtering titanium (Ti) and ruthenium oxide (RuO₂) onto the high-ordered titanium dioxide (TiO₂) nanotubes substrate. This process produced a well-distributed incorporation of Ti species within the RuO₂ coating. It has revealed that the presence of Ti element optimizes the surface morphology of electrode and modulates the electronic state of ruthenium (Ru) species, effectively preventing over-oxidation and thereby enhancing stability. The Ti/RuO₂@TiO₂ NTs self-supporting electrode exhibits remarkable electrocatalytic activity for CER, evaluated by lower overpotential (58 mV) at 10 mA cm^-2 and reduced Tafel slope (78 mV dec^-1) than that of other electrodes. Moreover, its mass activity achieving 478 mA mg_Ru^-1 at 1.3 V (vs SCE) is 4.3 times that of commercial dimensionally stable anodes (DSA). After operating for approximately 150 h at 100 mA cm^-2, the electrode exhibits minimal performance degradation, underscoring its exceptional stability. Additionally, the large potential difference between CER and OER makes it maintain high Cl₂ selectivity, achieving up to 91 % across varying current densities and reaction times. This work provides valuable strategy for designing novel Ru-based catalysts for practical CER applications in seawater and industrial environments.