Preparation and evaluation of nanoporous-pyramids structured silicon powder as an effective photocatalyst for degradation of methyl red

Abstract

In this paper, a new, simple, and relatively inexpensive method is reported to fabricate the hierarchical structure in silicon powder. Pyramidal texturing of silicon using alkaline etchants followed by metal-assisted etching (in hydrogen fluoride/Iron (III) chloride solution) to generate circular pores on the pyramids. This surface modification exhibited high efficiency of light absorption and reduction of light reflectance. An average reflectance reduced to ~ 4% in porous-pyramids structured silicon. The specific surface area increased from 2 to ~ 20 m2/g after porosification of pyramids structured silicon. And the absorption intensity increased, especially in the short wavelength. The energy gap of porous-pyramids structured silicon estimated as 1.6 eV from Tauc relation. The presence of combining pyramids and nanoporosification was the key factor to capture solar energy for eliminating environmental pollutants. To check the potential application of porous-pyramid silicon as a photocatalyst, the degradation of methyl red was measured after using it. The results reveal after 1 h, 95.8% degradation of methyl red.