Role of Graphene Oxide Aerogel Support on the CuZnO Catalytic Activity: Enhancing Methanol Selectivity in the Hydrogenation Reaction of CO2

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AbstractA novel CuZnO multicomponent catalyst, involving reduced graphene oxide (rGO) as a support, was synthesized to be applied in the catalytic hydrogenation of CO2 to methanol. The CuZnO@rGO composite was prepared as a 3D aerogel by a two‐step process involving supercritical CO2 for macrostructuration and H2 treatment for reduction. Electron microscopy was applied to visualize the meso/macroporous morphology formed by the supercritical drying. The elemental mapping depicted a homogenous distribution of CuZnO nanoparticles deposited on the rGO flakes. It was demonstrated that methanol production increases for the CuZnO@rGO composite in comparison to unsupported similar CuZnO nanoparticles. This behavior was ascribed to a different interaction established between the Cu0 and ZnO nanoparticles used as synthetized or deposited on rGO. It is shown that the highly reduced rGO component stimulates H2O desorption produced during the hydrogenation reaction, thus it serves as a support hindering the sintering of Cu0 nanoparticles. The formation of a diluted surface alloy of Zn into Cu0 was determined for the unsupported CuZnO NPs, while for the CuZnO@rGO aerogel composite, the absence of any additional phase, e. g., a surface alloy or reduced ZnO, was confirmed. The composite aerogels show excellent MeOH selectivity at high temperature (up to 260 °C) and low pressure (10 bar).