Efficient electrocatalytic bromine evolution and extraction from wastewater by oxygen vacancy enriched Ti/Ov-Co3O4-NRs electrode

Br − -containing wastewater has the risk of increasing Br − levels in receiving bodies if released into aquatic environments. Electrochemical oxidation is regarded as an ideal method for Br − removal and Br 2 extraction because of its simple procedure and high efficiency. In this work, a novel oxygen vacancy enriched Ti/O v -Co 3 O 4 -NRs electrode was fabricated and used for Br − removal and Br 2 extraction in Br − -containing wastewater. Characterization and experimental results showed that the Ti/O v -Co 3 O 4 -NRs electrode has more prominent bromine evolution reaction (BER) performance than several commercial electrodes (graphite, Ti/RuO 2 -Ir, Ti/PbO 2, etc.). Notably, the construction of oxygen vacancies obviously accelerated the removal of Br − (53 % improvement) by facilitating Br − adsorption and electron transfer. In addition, the influence factors such as initial pH, initial Br − concentration, current density, coexisting ions and temperature on Br − removal were optimized. The Ti/O v -Co 3 O 4 -NRs electrode also exhibited highly stable catalytic activity and conductivity. After 10 cycles, the removal rate of Br − decreased by 2.20 %, and the yield of Br 2 decreased by 3.6 %. In actual applications, the unit energy consumption reached 1.59–1.76 kJ·g −1 Br, and the current efficiency remained above 70 % throughout the whole treatment process. In addition, >80 % of the TOC could be removed during Br 2 extraction, which was more acceptable than the current reported experimental value of electrochemical Br 2 extraction and exhibited great application prospects.