High CO2 Photoreduction Performance Achieved with Ceria-Based Photocatalysts

High CO2 Photoreduction Performance Achieved with Ceria-Based Photocatalysts Olimpia Tammaro,1* Vincenzo Russo,2 Bruno Masenelli3, Matteo Tommasi4, Ilenia Rossetti4, Serena Esposito1 1Departement of Applied Science and Technology, Politecnico di Torino, Corso Duca degli Abruzzi 24, 10129 Turin, Italy 2 Department of Chemical Sciences, University of Naples Federico II, Complesso Universitario Monte Sant’Angelo, 80126 Naples, Italy 3 Université de Lyon, INSA-Lyon, ECL, UCBL, CPE, CNRS, INL-UMR5270, Villeurbanne, France 4 Chemical Plants and Industrial Chemistry Group, Dipartimento Chimica, Università degli Studi di Milano, CNR-SCITEC and INSTM Unit Milano Via C. Golgi 19, 20133 Milan, Italy e-mail: olimpia.tammaro@polito.it, The massive presence of CO2 in the atmosphere represents a global challenge for industry and academia to combat climate change that is affecting the environment with implications for human life. One promising approach to reduce the concentration of CO2 is photoconversion reactions. In these reactions, CO2, after being adsorbed onto an appropriate substrate, reacts with the reactive species generated when the substrate (photocatalyst) is illuminated with an appropriate light source (UV or visible light) [1]. The present research aims to design a high-performance catalyst capable of enhancing CO2 conversion under UV or visible light irradiation. In this scenario, cerium oxide (ceria) emerges as a promising candidate, due to the easy conversion between Ce(III) and Ce(IV) states which generates a strong catalytic potential without any structural modification of the fluorite structure. Furthermore, exploiting the doping with other metals is possible to tune the light absorption range. Among the heteroatom dopants, Fe3+ is a promising candidate as it can create defect states in the band gap or introduce energy levels in it. Fe-doped Ceria nanoparticles (NPs) have been synthetized by reverse microemulsion method conducted at room temperature. This approach involves the formation of an inner aqueous core, containing cerium and dopant precursors simultaneously, where a controlled nanoprecipitation takes place. The aqueous core stage acts as a nanoreactor, favoring the effective inclusion of heteroatoms in larger quantities. The adopted one-pot reverse micelle strategy allowed the preparation of mesoporous catalyst with a high nominal molar percentage of 2.5, 5, 7.5 and 10%. The set of prepared catalysts have been characterized by several techniques and their photocatalytic activity has been tested at 8 bar and compared with TiO2-P25 as benchmark commercial catalyst. For all the prepared samples the activity was higher than the benchmark P25. In particular the productivity of formic acid and the conversion of the hole scavenger both increased with Fe content. For instance, the catalysts with 2.5% and 5% of Fe showed a productivity of formic acid respectively of 22.1 mol/kgcat h and 26.8 mol/kgcat h of formic acid, respectively, vs. ca. 14 for P25. References [1] Conte F.; García-López E.I.; Marcì G.; Bianchi C.L.M.; Ramis G.; Rossetti I.,Catalysts, 2022, 12, 1628.