Photo–Hydrogen Generation by Silicon Nanowires from Water -Splitting Process

Abstract

Energy is the most basic need to survive on the earth from the very beginning of life. Out of many sources (i.e., biomass, wind energy, hydropower, nuclear energy and fossil fuels), light energy of sun is the most abundant and readily available renewable source on this planet. Therefore, to achieve a ‘Carbon-free future’, hydrogen is one of the best fit, produced by splitting of water using solar energy.1 Silicon, being the second most abundant material on earth and having superior band structure in nano-regime for efficient solar spectrum absorption, is chosen as the core photocatalyst material to make the whole process more efficient and cost-effective.2 Here, we have tried to fabricate vertically aligned Si-nanowire arrays by three different approaches with conventional Metal Assisted Chemical Etching method (MACE). Out of them, one is modified MACE method using Silica nanoparticles as masking layer where we can control the diameter and spacing between Si-NWs, second one is using Au layer as the protecting layer and rest is same. The last one is basic MACE method. Then hydrogenated and chlorinated to match the band edges with the water redox potential level.3–6 We have produced hydrogen by using the said system as a photo-anode under UV radiation in a quartz reactor and detected by gas chromatography. This result shows that the experiment is on the right path. In future, we will fabricate sub-10nm of diameter Si-NWs by modified MACE method and that can be used for the enhancement of the efficiency of the process.