F-doped β-MnO2 nanomaterials fabricated using a one-step plasma-assisted route display attractive functional performances in view of photo-activated self-cleaning/antifogging applications and wastewater treatment.
We report on a one-step hybrid atmospheric pressure plasma-liquid synthesis of ultra-small NiO nanocrystals (2 nm mean diameter), which exhibit strong quantum confinement and excellent compatibility as hole transport layer for various solar absorber layers.
and catalysis, capable of producing supported nanoparticles in a single synthesis step. [2][3][4][5][6][7] Exsolution was first observed on stoichiometric perovskite oxides where nanoparticles could be produced from transition metals present on the B-site of the perovskite oxide. This mechanism was initially referred to as solid-state recrystallization or self-regeneration. [8] Recently, however, the use of defect chemistry to synthesize the host oxides has revived the interest in exsolution because it allows a greater number of active cations, enhanced surface nucleation and nanoparticle growth and an overall faster and better controlled process. [3,9,10] Furthermore, the defect chemistry also allows for a structure that does not change when the reaction conditions change from oxidizing to reducing thus producing extremely controllable and stable catalysts. These advances have triggered fast growing research activities in the exsolution of nanoparticles and their application for environmental catalysis, solid oxide fuel cells, electrolysers, and chemical looping. [11][12][13][14][15][16][17][18][19] Exsolution is now an established term that refers to the growth of nanoparticles via the supply of metallic ionic species from an oxide host. This allows the formation of well anchored and partially embedded nanoparticles (socketed) on the support oxide, while also exhibiting crystallographic alignment. The application interest in exsolved nanoparticles High-performance nanoparticle platforms can drive catalysis progress to new horizons, delivering environmental and energy targets. Nanoparticle exsolution offers unprecedented opportunities that are limited by current demanding process conditions. Unraveling new exsolution pathways, particularly at low-temperatures, represents an important milestone that will enable improved sustainable synthetic route, more control of catalysis microstructure as well as new application opportunities. Herein it is demonstrated that plasma direct exsolution at room temperature represents just such a step change in the synthesis. Moreover, the factors that most affect the exsolution process are identified. It is shown that the surface defects produced initiate exsolution under a brief ion bombardment of an argon low-pressure and lowtemperature plasma. This results in controlled nanoparticles with diameters ≈19-22 nm with very high number densities thus creating a highly active catalytic material for CO oxidation which rivals traditionally created exsolved samples.
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