ZnO/perovskite core–shell nanorod array based monolithic catalysts with enhanced propane oxidation and material utilization efficiency at low temperature

• Successful integration of ZnO/perovskite core–shell nanorod arrays onto monolithic substrates by a hydrothermal and colloidal deposition combination method.
• Enhanced catalytic performance for propane oxidation in core–shell nanorod array based monolithic catalysts.
• A catalytic activity sequence of LaCoO3 > LaMnO3 > La2NiO4 on ZnO nanorod arrays revealed at the initial stage of catalytic reaction.
• Good dispersion and size control in perovskite nanoparticles contribute to the enhancement of catalytic performance.
• A new type of Pt-group metals (PGM) free catalysts with improved catalytic performance.

A hydrothermal strategy combined with colloidal deposition synthesis was successfully used to grow ZnO/perovskite (LaBO3, B = Mn, Co, Ni) core–shell nanorod arrays within three dimensional (3-D) honeycomb cordierite substrates. A facile sonication assisted colloidal wash coating process is able to coat a uniformly dispersed perovskite nanoparticles onto the large scale ZnO nanorod arrays rooted on the channel surfaces of the 3D cordierite substrate achieved by hydrothermal synthesis. Compared to traditional wash-coated perovskite catalysts, an enhanced catalytic performance was observed for propane oxidation with 25 °C lower light-off temperature than powder-form coated perovskite catalyst of similar LaMnO3 loading (4.3 mg). Temperature programmed reduction and desorption under H2 and O2 atmosphere, respectively, were used to study the reducibility and oxygen activity of these core–shell nanorod array based monolithic catalysts, revealing a catalytic activity sequence of LaCoO3 > LaMnO3 > La2NiO4 at the initial stage of catalytic reaction. The good dispersion and size control in La-based perovskite nanoparticles and their interfaces to ZnO nanorod array support may contribute to the enhancement of catalytic performance. This work may provide a new type of Pt-group metals (PGM) free catalysts with improved catalytic performance for hydrocarbon oxidations at low temperature.

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