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 ).