Enhanced Visible-Light Absorption and Photocurrent Generation of Three-Dimensional Metal–Dielectric Hybrid-Structured Films

The two-dimensional planar metal–semiconductor–metal sandwich structure can achieve single-band or multiband absorption. This sandwich structure is mostly affected by the thickness of the middle dielectric and the size of the top metal nanoparticles (NPs), which makes the absorption of the planar sandwich structure sensitive to the angle of the incident light. Here, three-dimensional (3D) metal–dielectric hybrid-structured films based on titanium dioxide (TiO2) and gold (Au) were designed and fabricated, which consist of three parts: an uneven Au film based on a porous substrate, a 50 nm TiO2 film, and top random Au nanoparticles. The 3D Au/TiO2–Au NP film exhibited a strong absorption and weak angle dependence in the visible-light range of 400–850 nm. The photocurrent density of the 3D Au/TiO2–Au NP film photoanode increased to 15.8 μA cm–2 at a potential of 1.23 V versus the reversible hydrogen potential under the irradiation of visible light (λ > 420 nm), resulting in an enhancement factor of ∼32 compared with the bare TiO2 photoanode (0.5 μA cm–2). This 3D metal–dielectric hybrid-structured film and its preparation strategy may have potential application value in photocatalysis, photoelectric conversion, and other solar absorption systems.