Photocatalysis has attracted much interest due to its potential advantages in utilizing solar energy to degrade organic pollutants and develop new energy[1–4]. As a traditional photocatalyst, semiconductor TiO2 has enormous potential in photocatalysis, but its wide band gap (3.2 eV) limits the use of light energy[5, 6].
Silicon materials, which exhibit a wide optical adsorption range, high optical absorption efficiency, and high electron mobility, become a great potential photoelectric conversion material for its important applications in the field of photovoltaics and photocatalysis[7–10]. The realization of the silicon structure, especially the preparation of nanowire arrays, is very significant for the development and production of efficient quantum devices, photoelectric devices, and electronic and optical sensors[11–15]. Various methods have been developed to prepare one-dimensional silicon nanostructures, such as chemical vapor deposition, supercritical fluid-liquid–solid synthesis, laser ablation, thermal evaporation decomposition, and other processes.
In recent years, a simple catalytic etching technique with metal particles as catalyst to prepare large-area aligned monocrystalline silicon nanowire arrays on silicon wafers has been reported[20–27]. The technique is actually a wet chemical corrosion, the process of which is relatively simple, low cost, and controllable. Recent works on the etching method with depositions of two-dimensional (2-D) micro/nanoparticle arrays[28–33] or 2-D nanopattern fabrications[34, 35] with highly ordered configurations, which are applicable for enabling highly dense nanowire formation, have also been reported. The controlled depositions of micro/nanoparticles result in close-packed highly ordered 2-D arrays with monolayer configuration, and these methods had been implemented in photonic devices[28–33]. In addition, the use of diblock copolymer lithography methods had enabled the fabrication of highly ordered and ultrahigh-density 2-D nanopattern arrays[34, 35]. However, literatures about the influence of etching solution composition on the morphologies and properties of Si nanowire arrays are rarely reported.
In this paper, we use monocrystalline silicon wafers as the matrix, Ag as the catalyst, and hydrofluoric acid (HF) and hydrogen peroxide (H2O2) as the etching solution to prepare silicon nanowire arrays utilizing the wet chemical etching method. The photoelectric properties of the monocrystalline silicon nanowire arrays and the silicon wafers were also investigated. Additionally, in our study, we found that the increase of H2O2 concentration can influence the morphology and surface characteristics of the nanowires, which may affect their light absorption and photocatalytic properties.