High chlorine evolution performance of electrochemically reduced TiO(2) nanotube array coated with a thin RuO(2) layer by the self-synthetic method

Recently, reduced TiO(2) nanotube arrays via electrochemical self-doping (r-TiO(2)) are emerging as a good alternative to conventional dimensionally stable anodes (DSAs) due to their comparable performance and low-cost. However, compared with conventional DSAs, they suffer from poor stability, low current efficiency, and high energy consumption. Therefore, this study aims to advance the electrochemical performances in the chlorine evolution of r-TiO(2) with a thin RuO(2) layer coating on the nanotube structure (RuO(2)@r-TiO(2)). The RuO(2) thin layer was successfully coated on the surface of r-TiO(2). This was accomplished with a self-synthesized layer of ruthenium precursor originating from a spontaneous redox reaction between Ti(3+) and metal ions on the r-TiO(2) surface and thermal treatment. The thickness of the thin RuO(2) layer was approximately 30 nm on the nanotube surface of RuO(2)@r-TiO(2) without severe pore blocking. In chlorine production, RuO(2)@r-TiO(2) exhibited higher current efficiency (∼81.0%) and lower energy consumption (∼3.0 W h g(−1)) than the r-TiO(2) (current efficiency of ∼64.7% of and energy consumption of ∼5.2 W h g(−1)). In addition, the stability (ca. 22 h) was around 20-fold enhancement in RuO(2)@r-TiO(2) compared with r-TiO(2) (ca. 1.2 h). The results suggest a new route to provide a thin layer coating on r-TiO(2) and to synthesize a high performance oxidant-generating anode.