Rough gold films as broadband absorbers for plasmonic enhancement of TiO(2) photocurrent over 400–800 nm

Recent years have witnessed an increasing interest in highly-efficient absorbers of visible light for the conversion of solar energy into electrochemical energy. This study presents a TiO(2)-Au bilayer that consists of a rough Au film under a TiO(2) film, which aims to enhance the photocurrent of TiO(2) over the whole visible region and may be the first attempt to use rough Au films to sensitize TiO(2). Experiments show that the bilayer structure gives the optimal optical and photoelectrochemical performance when the TiO(2) layer is 30 nm thick and the Au film is 100 nm, measuring the absorption 80–90% over 400–800 nm and the photocurrent intensity of 15 μA·cm(−2), much better than those of the TiO(2)-AuNP hybrid (i.e., Au nanoparticle covered by the TiO(2) film) and the bare TiO(2) film. The superior properties of the TiO(2)-Au bilayer can be attributed to the rough Au film as the plasmonic visible-light sensitizer and the photoactive TiO(2) film as the electron accepter. As the Au film is fully covered by the TiO(2) film, the TiO(2)-Au bilayer avoids the photocorrosion and leakage of Au materials and is expected to be stable for long-term operation, making it an excellent photoelectrode for the conversion of solar energy into electrochemical energy in the applications of water splitting, photocatalysis and photosynthesis.