Nanotechnology

Electrode

Anode

Engineering

Physical chemistry

Composite material

Chemistry

Materials science

Diamond

Cathode

Electrolyte

Chemical engineering

Optoelectronics

Electrochemistry

Doping

Environmental Science & Technology

Efficient, inexpensive, and stable electrode materials are key components of commercially viable electrochemical wastewater treatment system. In this study, blue-black TiO2 nanotube array (BNTA) electrodes are prepared by electrochemical self-doping. The 1-D structure, donor state density, and Fermi energy level position are critical for maintaining the semimetallic functionality of the BNTA. The structural strength of the BNTA is enhanced by surface crack minimization, reinforcement of the BNTA-Ti metal interface, and stabilized by a protective overcoating with nanoparticulate TiO2 (Ti/EBNTA). Ti/EBNTA electrodes are employed as both anodes and cathodes with polarity switching at a set frequency. Oxidants are generated at the anode, while the doping levels are regenerated along with byproduct reduction at the cathode. The estimated maximum electrode lifetime is 16 895 h. Ti/EBNTA has comparable hydroxyl radical production activity (6.6 × 10-14 M) with boron-doped diamond (BDD, 7.4 × 10-14 M) electrodes. The chlorine production rate follows a trend with respective to electrode type of Ti/EBNTA > BDD > IrO2. Ti/EBNTA electrodes operated in a bipolar mode have a minimum energy consumption of 62 kWh/kg COD, reduced foam formation due to less gas bubble production, minimum scale formation, and lower chlorate production levels (6 mM vs 18 mM for BDD) during electrolytic wastewater treatment.

Synthesis and Stabilization of Blue-Black TiO<sub>2</sub> Nanotube Arrays for Electrochemical Oxidant Generation and Wastewater Treatment

Synthesis and Stabilization of Blue-Black TiO2 Nanotube Arrays for Electrochemical Oxidant Generation and Wastewater Treatment

Synthesis and Stabilization of Blue-Black TiO₂ Nanotube Arrays for Electrochemical Oxidant Generation and Wastewater Treatment