Yeast bio-template synthesis of porous anatase TiO2 and potential application as an anode for sodium-ion batteries

Porous anatase TiO2 samples have been prepared by a bio-template route using low-cost yeast cells as templates. The structure, morphology and electrochemical performance of the prepared samples have been characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), transmission electron microscopy (TEM), Brunauer-Emmett-Teller (BET) analysis, galvanostatic charge/discharge tests and cyclic voltammograms (CV). The results showed that the prepared samples have a hierarchical porous structure replicated from the microstructure of yeast template, which combines macropores (1.5-2.5 μm) and thin pore wall (0.2-0.7 μm) composed by mesopore (9.78 nm) and 10-20 nm active material. The prepared porous TiO2 delivered a discharge capacity of about 255.98 mAh g−1 and its capacity retention was about 80% after 100 cycles at 1/3C. Remarkably, it still showed a high discharge capacity of 112.93 and 84.65 mAh g−1 even at 5 and 10C, respectively. The good rate performance can be ascribed to the hierarchical porous structure, which provided good access of the electrolyte to the electrode interface, reducing path lengths for ion diffusion and accommodating volume changes during cycling.