Highly enhanced electrocatalytic activity of nano-TiO2/Ti membrane electrode for phenol wastewater treatment

Nano-TiO2/Ti composite membrane electrodes with different morphological TiO2, including nanoparticles (NP), nanowires (NW), and nanosheets (NS), were successfully prepared by hydrothermal reaction process under different hydrothermal temperatures. The effects of the morphology of TiO2 catalyst on the structure and properties of TiO2/Ti composite membrane electrodes were evaluated by X-ray diffraction, field-emission scanning electronic microscopy, and X-ray Photoelectron spectroscopy. Compared with both NP-TiO2/Ti and NS-TiO2/Ti, it was found that NW-TiO2/Ti had lower charge transfer resistance and larger peak current. Electrocatalytic membrane reactor (ECMR) has been successfully designed for the treatment of phenolic wastewater, which is assembled with a TiO2/Ti composite membrane electrode as an anode. ECMR with NW-TiO2/Ti had the best electrochemical activity, whose phenol removal rate was 93.13%, but was 84.25%, 82.72%, and 46.86% in the case of NS-TiO2/Ti, NP-TiO2/Ti, and Ti electrodes, respectively. Meanwhile, comparing with others, ECMR with NW-TiO2/Ti had the lowest energy consumption (0.756 kWh/kgCOD). The results demonstrated that the excellent electrochemical performance of ECMR with NW-TiO2/Ti was deeply related to the nanowire morphology of TiO2 catalyst coated on Ti substrate electrode, which was mainly reflected in the larger effective electrocatalytic surface area and higher electron transfer rate of NW-TiO2/Ti composite membrane electrode.