Recent Advances in the Use of Silicon-Based Photocathodes for Solar Fuel Production

With the substantial decrease in the world’s reservoirs of fossil fuels, the need to develop industrial-scale energy-harvesting systems that rely on more sustainable sources is dire. With solar energy being the cheapest, and most giving, research progress utilizing it to replace fossil fuels, as well as to counterbalance the effects of using such fuels, is divided into three tracks: finding cheap and efficient photoabsorbers, devising industrially compatible fabrication procedures, and developing the proposed systems for higher efficiency. Being an abundant element with well-known chemical and electrical properties and well-established fabrication procedures, silicon may be the quickest solution for developing efficient solar energy conversion systems. Indeed, for H₂ production and CO₂ reduction in particular, Si-based materials with different morphologies, structural forms, and combinations were studied for decades. In this chapter, the recent studies for Si photocathodes are demonstrated in a way to classify the different systems and compare their performance. The use of plain and decorated nanostructured Si, as well as SiC nanostructured crystalline photocathodes for solar H₂ production, is briefly presented. Brief insight about amorphous Si and its use for the same purpose is also discussed. Finally, light is shed on the use of Si photocathodes in CO₂ reduction.