Figure 27.

Comparing the PEC properties of four different photoanodes: TiO₂ nanorods (dark purple solid line), TiO₂ nanorod photonic crystals (green solid line), Au/TiO₂ nanorods (pink solid line), and Au/TiO₂ nanorod photonic crystals (pale purple solid line) [257]. (a) Chronoamperometry measurements performed at an external potential of 1 V vs. Reversible Hydrogen Electrode (RHE). The on/off circles indicate simulated sunlight illumination. (b) Linear sweep voltammetry measurements for a scan rate of 50 mV/s under dark (dotted lines) and illuminated conditions. (c) Photoconversion efficiency as a function of applied potential versus RHE. (d) The resultant evolution of H₂ and O₂ gases for the four photoanodes under simulated sunlight illumination. Of particular note are the IPCE results in (e) which displays the shapes of the IPCE active spectra of the various Au/TiO₂ composite photoanodes. PEC activity within the visible light regime is observed due to the presence of the Au noble metal nanoparticles. Furthermore, the shapes of the IPCE spectra as shown in the inset are noted to be similar to that of LSPR absorption spectra of Au nanoparticles. (f) Amperometric I-t curves for the four different photoanodes for repeated on-off cycles of simulated sunlight. Reprinted with permission from Ref [257] Copyright Royal Society of Chemistry (2014).