Constructing dimensionally stable TiO2 nanotube arrays/SnO2/RuO2 anode via successive electrodeposition for efficient electrocatalytic oxidation of As(III)

Arsenic-containing water needs to be purified to reduce the global hazards of arsenic to human health and ecosystems. Herein, successive electrodeposition of SnO2 and RuO2 nanoparticles on the TiO2 nanotube arrays (TNTAs) was performed to synthesize dimensionally stable TNTAs/SnO2/RuO2 anodes for highly efficient electrocatalytic oxidation of As(III) in aqueous solution. Such a TNTAs/SnO2/RuO2 anode possessed fast charge transfer, higher oxygen evolution potential (OEP), larger electrocatalytic active area, and excellent stability, and delivered effectively electrocatalytic oxidation As(III), of which 10 mg/L of As(III) was completely oxidized into As(Ⅴ) with lower toxicity within 20 min owing to the synergistic effect of RuO2 and SnO2. Impressively, the optimized TNTAs/SnO2/RuO2-10 anode presented an excellent electrochemical stability and longer service lifetime, and its oxidation conversion efficiency of As(III) still could be maintained to be 98% as well as its kinetic reaction constant decreased by only 0.03 even after 11 recycled usage, which was ascribed to the intensified interaction between RuO2 and TNTAs/SnO2. The excellence of the innovative anode was also evidenced through its strong anti-interference ability to coexisting ions and the elucidation of the associated oxidation reaction mechanism of As(III) on the surface of the anode by electron spin resonance and radical scavenger tests. This novel electrode integrates high electrocatalytic activity, high electron transport and high stability, ensures the long-term stable use of the electrode, while realizes efficient and rapid electrocatalytic oxidation of As(III) in aquatic environments. This work provides new ideas for further improving the catalytic performance and stability of dimensionally-stable anode materials.