The Si nanopillars with high aspect ratio were fabricated by dry-etching the thin SiO(2)-covered Si substrate with a rapidly self-assembled Ni nanodot patterned mask. Aspect-ratio-dependent ultra-low reflection and anomalous luminescence of Si nanopillars are analyzed for applications in all-Si based lighting and energy transferring systems. The Si nanopillars induce an ultra-low reflectance and refractive index of 0.88% and 1.12, respectively, at 435 nm due to the air/Si mixed structure and highly roughened surface. The reflectance can be <10% with a corresponding refractive index of<1.80 between 190 and 670 nm. Lengthening the Si nanopillars from 150 +/- 15 to 230 +/- 20 nm further results in a decreasing reflectance, corresponding to a reduction in refractive index by Delta n/n = 18% in the visible and near-infrared wavelength region. After dry-etching an Si wafer into Si nanopillars, the weak blue-green luminescence with double consecutive peaks at 418-451 nm is attributed to the oxygen defect (O(2-))-induced radiation, which reveals less relevance with the ultra-low-reflective Si nanopillar surface.

In this paper, Cu(x)O photocatalyst on plasmonic nanoporous Au film is proposed to enhancing the H(2) evolution rate of pure water splitting. The nanoporous Au film can simultaneously provide surface-enhanced absorption and built-in potential. The reflection spectrum shows that the surface plasmon (SP) assisted absorption wavelength of the Cu(x)O on the nanoporous Au film can be modified by changing the annealing temperature. It is found that the enhancement of the H(2) evolution rate highly depends on the SP-assisted absorption. As the annealing temperature is 220 ° C, the H(2) evolution rate is 58 μmol hr(-1) under the condition that the device area is 0.25 cm(2).

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