Study of electrocatalysts deposition onto TiO2 protective coatings in photoelectrochemical systemsTuesday (27.09.2016) 15:30 - 15:45 Part of:
Photoelectrochemical systems are based on light-absorbing materials, which can be excited by photons and generate charge carriers. In turn, these carriers can facilitate oxidative or reductive reactions in the surface of the material to obtain chemical fuels, important for energy storage. These absorbing materials usually are semiconductors, but its electrochemical instability in aqueous systems is a common problem in the development of photoelectrochemical devices, as the water contact provokes the oxidation of the surface. One of the most used approaches to avoid this issue involves protective coatings, as thin-film metal oxides like TiO2. In this work, thin-films of 100 nm of TiO2 are deposited directly onto silicon (p+ or n+ depending on the photoelectrode) by atomic layer deposition (ALD) technique. Based on this substrate, different electrocatalysts are studied and optimized for an enhanced performance and stability onto TiO2. In particular, for photoanodes using p+ silicon, thermally evaporated Ni with different annealing conditions is compared with electrochemically deposited (Ni-Fe)Ox or Ni-Mo, and its chemical and electrochemical properties are evaluated. For photocathodes using n+ silicon, several techniques of Pt deposition are studied and tested, as thermal evaporation, drop casting or photo-electrodeposition, among others. Also, the use of a thin titanium adhesion layer is evaluated in order to increase the stability of the Pt coating.