Figure 2

SEM cross-sectional images of the TiO₂ photo-electrode films with acetylene-black of (a) 0 and (b) 1.5 wt%. (c), (d) Enlarged SEM image from the cross-section (red circle) of TiO₂ photo-electrode films with an acetylene-black of 0 and 1.5 wt%, respectively.