Figure 5: Characterization and PEC water-splitting performance of TiO2 NWs with high W- and C-doping concentrations.

(a) TEM and high-resolution TEM images of W/C no. 2 (W: 17.5 at.%, C: 18.3 at.% at the NW surface). Scale bar, 50 nm (TEM) and 5 nm (high-resolution TEM). (b) STEM image. Scale bar, 50 nm. (c) Concentration profiles of W and C dopants along the NW diameter in W/C no. 2. Comparison of W/C no. 1 (blue) and W/C no. 2 (red) with (d), three electrodes J–V curves (W/C no. 1, W: 10.2 at.%, C: 13.1 at.% at the NW surface), (e) IPCE, (f) light absorption (quartz substrate), (g) charge transfer efficiency and (h) charge transport efficiency. The data of undoped TiO2 NWs (black) are added for reference.