“…The equipment and measurement methods such as field-emission scanning electron microscope (FE-SEM; S4800S; Hitachi & Horiba Co., Tokyo, Japan), transmission electron microscope (TEM; JEM-ARM200F; JEOL Co., Tokyo, Japan), and diffuse reflectance UV-Vis-NIR spectrophotometer (SolidSpec-3700; Shimadzu Co., Tokyo, Japan) used in this study for the surface characterization of the Au and Pt multi-coated TiO 2 nanotubes are the same as in our previous study [24]. The X-ray photoelectron spectroscopy (XPS; K-Alpha; Thermo Fisher Scientific Inc., Waltham, MA, USA) was equipped with a monochromatic A1 Kα source.…”