Platinum-Supported Zirconia Nanotube Arrays Supported on Graphene Aerogels Modified with Metal-Organic Frameworks: Adsorption and Oxidation of Formaldehyde at Room Temperature.

Precious-metal catalysts (e.g., Au, Rh, Ag, Ru, Pt, and Pd) supported on transition-metal oxides (e.g., Al2 O3 , Fe2 O3 , CeO2 , ZrO2 , Co3 O4 , MnO2 , TiO2 , and NiO) can effectively oxidize volatile organic compounds. In this study, porous platinum-supported zirconia materials have been prepared by a "surface-casting" method. The synthesized catalysts present an ordered nanotube structure and exhibited excellent performance toward the catalytic oxidation of formaldehyde. A facile method, utilizing a boiling water bath, was used to fabricate graphene aerogel (GA), and the macroscopic 3D Pt/ZrO2 -GA was modified by introducing an adjustable MOF coating by a surface step-by-step method. The unblocked mesoporous structure of the graphene aerogel facilitates the ingress and egress of reactants and product molecules. The selected 7 wt.% Pt/ZrO2 -GA-MOF-5 composite demonstrated excellent performance for HCHO adsorption. Additionally, this catalyst achieved around 90 % conversion when subjected to a reaction temperature of 70 °C (T90 % =70 °C). The Pt/ZrO2 -GA-MOF-5 composite induces a catalytic cycle, increasing the conversion by simultaneously adsorbing and oxidizing HCHO. This work provides a simple approach to increasing reactant concentration on the catalyst to increase the rate of reaction.