Hydrogen and Oxygen Evolution in a Membrane Photoreactor Using Suspended Nanosized Au/TiO2 and Au/CeO2

• Published in: ChemEngineering Vol. 3; no. 1; p. 5
• Main Authors: Marino, Tiziana, Figoli, Alberto, Molino, Antonio, Argurio, Pietro, Molinari, Raffaele
• Format: Journal Article
• Language: English
• Published: Basel MDPI AG 01-03-2019
• Subjects: Aqueous solutions; Catalytic activity; Cerium oxides; Chemical engineering; Chemical evolution; Electrolytes; Ferric ions; Fossil fuels; Gold; Hydrogen; Hydrogen evolution; Ion concentration; Light; Membrane reactors; Membranes; Nanoparticles; Oxidation; Oxygen; Particle size; Phenols; Photocatalysis; photocatalytic membrane reactor; Semiconductors; Solar energy; Titanium dioxide; Water splitting; Z-scheme
• ISSN: 2305-7084; 2305-7084
• DOI: 10.3390/chemengineering3010005

Photocatalysis combined with membrane technology could offer an enormous potential for power generation in a renewable and sustainable way. Herein, we describe the one-step hydrogen and oxygen evolution through a photocatalytic membrane reactor. Experimental tests were carried out by means of a two-compartment cell in which a modified Nafion membrane separated the oxygen and hydrogen evolution semi-cells, while iron ions permeating through the membrane acted as a redox mediator. Nanosized Au/TiO2 and Au/CeO2 were employed as suspended photocatalysts for hydrogen and oxygen generation, respectively. The influence of initial Fe3+ ion concentration, ranging from 5 to 20 mM, was investigated, and the best results in terms of hydrogen and oxygen evolution were registered by working with 5 mM Fe3+. The positive effect of gold on the overall water splitting was confirmed by comparing the photocatalytic results obtained with the modified/unmodified titania and ceria. Au-loading played a key role for controlling the photocatalytic activity, and the optimal percentage for hydrogen and oxygen generation was 0.25 wt%. Under irradiation with visible light, hydrogen and oxygen were produced in stoichiometric amounts. The crucial role of the couple Fe3+/Fe2+ and of the membrane on the performance of the overall photocatalytic system was found.