RESUMO
In this work, we showed the tuning of the catalytic behavior of dendritic plasmonic colloidosomes (DPCs) by plasmonic hotspots. A cycle-by-cycle solution-phase synthetic protocol yielded high-surface-area DPCs by controlled nucleation-growth of gold nanoparticles. These DPCs, which had varying interparticle distances and particle-size distribution, absorb light over the entire visible region as well as in the near-infrared region of the solar spectrum, transforming gold into black gold. They produced intense hotspots of localized electric fields as well as heat, which were quantified and visualized by Raman thermometry and electron energy loss spectroscopy plasmon mapping. These DPCs can be effectively utilized for the oxidation reaction of cinnamyl alcohol using pure oxygen as the oxidant, hydrosilylation of aldehydes, temperature jump assisted protein unfolding and purification of seawater to drinkable water via steam generation. Black gold DPCs also convert CO2 to methane (fuel) at atmospheric pressure and temperature, using solar energy.
RESUMO
Mimicking enzymatic activity is a challenging task. Herein we report dendritic fibrous nano-silica (DFNS) supported gold (Au) nanoparticles (DFNS/Au) as a peroxidase like artificial enzyme. It showed a superior enzymatic activity in 3,5,3',5'-tetramethylbenzidine (TMB) oxidation chosen as a model reaction, significantly higher than natural horseradish peroxidase (HRP) enzyme as well as other reported nanomaterial based artificial enzymes. A solvent dependent selectivity towards a two-electron oxidation product, TMB-diamine, has also been observed. This study clearly indicates the vital role of the fibrous morphology and unique silica channels of DFNS in the enhancement of the enzymatic activity.
RESUMO
A practical and convenient decarbonylation of a variety of aromatic, heteroaromatic, and alkenyl aldehydes by using palladium nanoparticles supported on novel, fibrous nanosilica, named KCC-1-PEI/Pd, has been developed. Complete conversion of aldehyde functionalities into deformylated products was achieved in all cases and in nearly all cycles tested by reusing the catalyst systems. This method eliminates further purification of products after their isolation. Syntheses of at least three different deformylated products have been shown in sequence with the same catalyst system, which neither requires use of any additives, such as oxidants and bases, nor CO scavengers.