Photocatalytic Hydrogen Production Using Porous 3D Graphene-Based Aerogels Supporting Pt/TiO(2) Nanoparticles

Composites involving reduced graphene oxide (rGO) aerogels supporting Pt/TiO(2) nanoparticles were fabricated using a one-pot supercritical CO(2) gelling and drying method, followed by mild reduction under a N(2) atmosphere. Electron microscopy images and N(2) adsorption/desorption isotherms indicate the formation of 3D monolithic aerogels with a meso/macroporous morphology. A comprehensive evaluation of the synthesized photocatalyst was carried out with a focus on the target application: the photocatalytic production of H(2) from methanol in aqueous media. The reaction conditions (water/methanol ratio, catalyst concentration), together with the aerogel composition (Pt/TiO(2)/rGO ratio) and architecture (size of the aerogel pieces), were the factors that varied in optimizing the process. These experimental parameters influenced the diffusion of the reactants/products inside the aerogel, the permeability of the porous structure, and the light-harvesting properties, all determined in this study towards maximizing H(2) production. Using methanol as the sacrificial agent, the measured H(2) production rate for the optimized system (18,800 µmol(H2)h(−1)g(NPs)(−1)) was remarkably higher than the values found in the literature for similar Pt/TiO(2)/rGO catalysts and reaction media (2000–10,000 µmol(H2)h(−1)g(NPs)(−1)).