Highly enhanced electrocatalytic activity of nano-TiO_2/Ti membrane electrode for phenol wastewater treatment

摘要

Nano-TiO_2/Ti composite membrane electrodes with different morphological TiO_2, 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 TiO_2 catalyst on the structure and properties of TiO_2/Ti composite membrane electrodes were evaluated by X-ray diffraction, field-emission scanning electronic microscopy, and X-ray Photoelectron spectroscopy. Compared with both NP-TiO_2/Ti and NS-TiO_2/Ti, it was found that NW-TiO_2/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 TiO_2/Ti composite membrane electrode as an anode. ECMR with NW-TiO_2/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-TiO_2/Ti, NP-TiO_2/Ti, and Ti electrodes, respectively. Meanwhile, comparing with others, ECMR with NW-TiO_2/Ti had the lowest energy consumption (0.756 kWh/kgCOD). The results demonstrated that the excellent electrochemical performance of ECMR with NW-TiO_2/Ti was deeply related to the nanowire morphology of TiO_2 catalyst coated on Ti substrate electrode, which was mainly reflected in the larger effective electrocatalytic surface area and higher electron transfer rate of NW-TiO_2/Ti composite membrane electrode.