Bacteria-Assisted Synthesis of Nanosheet-Assembled TiO2 Hierarchical Architectures for Constructing TiO2-Based Composites for Photocatalytic and Electrocatalytic Applications.

Synthesis and application of three-dimensional TiO2 hierarchical architectures are one of the major priorities in the research and development of TiO2 catalysts. Using bacteria as a template and a reactor, a bioinspired strategy was developed in the present study to synthesize nanosheet-assembled TiO2 hierarchical architectures (N-TiO2-HA) and relative composites for photocatalytic and electrocatalytic applications. In the first part of this work, three kinds of bacteria were used for the synthesis of N-TiO2-HA with satisfactory monodispersity, and the growth mechanism was investigated. In the second part, porous TiO2 hollow spheres (P-TiO2-HS), which were obtained by calcining N-TiO2-HA at 750 °C in air, were incorporated with MIL-101(Fe) to improve the visible-light photocatalytic efficiency. The results of the photo-Fenton-assisted degradation of rhodamine B and ciprofloxacin indicate that the synthesized composites have excellent visible-light photocatalytic activity. In the third part, the nanosheet-assembled TiO2-carbon hollow spheres (N-TiO2-C-HS), which were obtained by calcining N-TiO2-HA at 750 °C in argon atmosphere, were electrodeposited with Pt for electrocatalytic oxidation of methanol. The electrochemical measurements show that Pt-deposited N-TiO2-C-HS have better electrocatalytic activity, stability, and tolerance to CO poisoning than commercial Pt/C catalysts.