Drastic Microwave Heating of Percolated Pt Metal Nanoparticles Supported on Al2O3 Substrate

Abstract

Microwave (MW) heating of supported metal nanoparticles (NPs) presents attractive effects on catalysis such as the rapid heating processes and the enhancement of the reaction rate. Improving the heating property of the NPs, which act as the catalytic active sites, the MW effects will become more significant. Here we show a systematic study about the supported Pt NPs structure to improve the MW heating property. We found that the drastic heating was induced by a percolated Pt NPs structure, where the conduction electrons move around in the two-dimensional network. On the other hand, no heating was observed in an isolated Pt NPs system with the confined electrons. We conclude that the percolation of the Pt NPs giving the network structure is one of the important key factors for the efficient MW heating. The optimized Pt NPs catalyst leads to the dramatic MW effects on catalytic reactions.

Designing Local Microwave Heating of Metal Nanoparticles/Metal Oxide Substrate Composites

“…The loading of Pt NPs on the MO x substrates was varied by changing the sputtering time in the range 20–180 s (Figure A). According to our previous paper, the sputtering for 60 s deposits 10.5 nmol of Pt on the 5 mm × 5 mm substrate . A sputtering time of 60 s ensured the maximum level of MW heating (Figure B).…”

“…Metal nanoparticles (NPs) are selectively heated by MWs when supported on metal oxide (MO x ) catalyst supports such as Al 2 O 3 or SiO 2 , which are generally transparent to MWs. , The reaction is accelerated by the rapid formation of high-temperature “hotspots” at the catalyst active sites, enabled by the direct MW irradiation of the supported metal NPs. Jie et al reported that the use of MWs accelerates the dehydrogenation of fossil fuels using Fe@SiC catalyst by selectively heating the Fe NPs and enables a very high selectivity for hydrogen production. , Deng et al reported that the selective heating of Fe supported on a zeolite catalyst with a low Si/Al ratio by MWs promoted the dehydroaromatization of methane .…”

“…Marquardt et al reported that the dielectric properties of metal particles in a range 10 nm to 10 μm depend on their size . More MW heating occurs when the supported metal NPs are in contact with each other than when they are isolated owing to the conduction loss between the metal NPs. ,, Some MO x NPs such as perovskite oxides, supported on cordierite, also exhibit rapid MW heating …”

“…25 More MW heating occurs when the supported metal NPs are in contact with each other than when they are isolated owing to the conduction loss between the metal NPs. 7,26,27 Some MOx NPs such as perovskite oxides, supported on cordierite, also exhibit rapid MW heating. 28 Herein, we report the interaction between metal NPs and MOx supports to design their optimum structure in which efficient MW energy can be applied.…”

Designing Hypoxia‐Responsive Nanotheranostic Agents for Tumor Imaging and Therapy

“…Metal nanoparticles are widely used in catalysis, [ 84 ] imaging, [ 85 ] and medicine [ 86 ] due to their high specific surface area, nanoscale size and unique physicochemical properties. In the acidic environment of hypoxic tumor tissues, the catalytic capacity of many metal nanoparticles can be activated to convert H 2 O 2 to oxygen and water molecules or hydroxyl radicals.…”