Capturing Irradiation with Nanoantennae: Plasmon‐Induced Enhancement of Photoelectrolysis

Abstract

In solving the energy challenge of solar irradiation′s inconsistency, a desirable approach is mimicking nature′s photosynthesis by collecting and storing solar energy via water splitting. TiO2 is a promising candidate, a wide‐gap semiconductor with low cost, high efficiencies in the UV region, and photostability. Its shortcomings in the visible spectrum can be improved via band gap engineering, mainly co‐catalyst doping, thereof Au nanoparticles. In contrast, we deposit a structured semiconductor on a plasmonic‐active co‐catalyst: we reverse the species order with respect to illumination and achieve a patterned structure for both species in which TiO2 pillars are grown on a Raman‐active Au substrate. The pillars act as antennae, coupling incoming light absorption while feeding on the substrate′s plasmonic effects. The aforementioned system shows impressive incident‐photon‐to‐current efficiencies (IPCEs) in the visible region, along with increased photocurrents in the UV and red shifts depending on deposition depth, diameter, and annealing temperature. We were able to tune the system′s photoresponse by changing the nanostructure geometry and therewith tuned the resonance to the incoming irradiation.

Determining the Efficiency of Photoelectrode Materials by Coupling Cavity‐Microelectrode Tips and Scanning Electrochemical Microscopy

“…Most frequently, the choice is based on a compromise between stability and activity, the latter depending on the range of frequencies that the semiconductor can absorb. For example, titanium dioxide has a sufficient stability but its wide band gap (around 3.2 eV) excludes the absorption of visible light . On the other hand, materials like WO 3 , Fe 2 O 3 , BiVO 4 or Cu(I) and Cu(II) oxides can absorb part of the visible spectrum but are still under characterization in terms of stability and performances …”