Desenvolvimento de fotoeletrodos de si com micro e nanotexturação : otimização do contato posterior e do cocatalisador de superfície

Abstract

The photoelectrochemical process of water for H2 and O2 production is a promising alternative to the predominant high environmental impact energy sources in the global energy matrix. In this process, semiconductor-based photoelectrodes convert the energy emitted by the sun into photogenerated voltage and current that promote the breakdown of the water molecule. The present work is dedicated to the manufacture, optimization and characterization of p-type silicon photoelectrodes, aiming to improve their ability to capture incident photons and to carry charge carriers at the front and rear interfaces. Surface texture via anisotropic chemical etching and selective etching improve the optical properties of the photoelectrode by reducing the average weighted reflectance by 6.18% and 25.27% respectively. Significantly increase the surface area of photoelectrodes. The implementation of adequate metal film preparation and deposition processes for back contact creation and decoration with surface co-catalysts via magnetron sputtering (MS) optimized for textured surfaces has obtained significant improvement in photoelectrode efficiency. The processes developed in this work achieved results such as: 1.63% efficiency for as-cut palladium cocatalyst photoelectrodes with 60 s deposition via MS and 3.26% efficiency with platinum cocatalyst with 30 s deposition; 2.97% efficiency for nanotextured photoelectrode via selective etching with 2.5 min time of chemical etching and with 15 sec deposition cocatalyst; 5.07% efficiency for microtextured photoelectrode via anisotropic chemical etching with platinum surface cocatalyst with 45 s deposition time.