Selectivity in the Ligand Functionalization of Photocatalytic Metal Oxide Nanoparticles for Phase Transfer and Self‐Assembly Applications

Abstract

The functionalization of photocatalytic metal oxide nanoparticles of TiO 2 , ZnO, WO 3 and CuO with amineterminated (oleylamine) and thiol-terminated (dodecane-1thiol) alkyl-chain ligands was studied under ambient conditions. A high selectivity was observed in the binding specificity of a ligand towards nanoparticles of these different oxides. It was observed that oleylamine binds stably to only TiO 2 and WO 3 , whereas dodecane-1-thiol binds stably only to ZnO and CuO. Similarly, polar-to-nonpolar solvent phase transfer of TiO 2 and WO 3 nanoparticles could be achieved by using oleylamine, but not dodecane-1-thiol, whereas the opposite holds for ZnO and CuO. The surface chemistry of ligand-functionalized nanoparticles was probed by attenu-ated total reflectance (ATR)-FTIR spectroscopy, which enabled the occupation of the ligands at the active sites to be elucidated. The photostability of the ligands on the nanoparticle surface was determined by the photocatalytic selfcleaning properties of the material. Although TiO 2 and WO 3 degrade the ligands within 24 h under both UV and visible light, ligands on ZnO and CuO remain unaffected. The gathered insights are also highly relevant from an application point of view. As an example, because the ligand-functionalized nanoparticles are hydrophobic in nature, they can be self-assembled at the air-water interface to give nanoparticle films with demonstrated photocatalytic as well as antifogging properties.

Plasmon resonance of gold and silver nanoparticle arrays in the Kretschmann (attenuated total reflectance) vs. direct incidence configuration

“…When plasmonic nanostructures are arranged periodically, electrodynamic coupling of the nanostructures enhances the light-matter interaction as compared to isolated nanostructures 1 , 2 . Thus, periodic arrays of nanostructures have gained increasing attention in recent years for the application in light driven processes such as solar energy harvesting 3 , photovoltaics 4 , photocatalysis 5 , 6 , SERS (surface-enhanced Raman spectroscopy) 7 , fluorescence 8 , SEIRA (surface-enhanced infrared absorption spectroscopy) 9 , sensing 10 , photoemission and photodetection 11 , etc. The plasmonic enhancement of these various processes can occur through different mechanisms.…”

Microwave‐Assisted Synthesis of ZnO Nanoparticles: Phase Transfer to Water

“…[ 8 ] Particle extraction through liquid–liquid interface for colloidal processing of ZnO particles was also performed with the use of octanohydroxamic acid and bufexamac as extractors. [ 9 ] Lenaerts et al [ 10 ] found that a polar‐to‐nonpolar solvent phase transfer of TiO 2 and WO 3 nanoparticles could be achieved by using oleylamine, but not dodecane‐1‐thiol, whereas the opposite holds for ZnO and CuO. In contrast to most phase transfer agents in use, polysorbate 80 is a synthetic nonionic surfactant of highly proven safety, which makes it useful for drug formulation.…”

Effect of size distribution, skewness and roughness on the optical properties of colloidal plasmonic nanoparticles

“…The particle size distribution for specific values of μ and σ was obtained by the iterative procedure. The number of particles, NTotal had to be first estimated with different values until the total number of atoms calculated from the entire distribution of nanoparticles with the given μ and σ results in 1.5055 x 10 19 . The molar mass and density values used in the calculations were 107.9 gm/mole and 10.5 gm/cm 3 .…”

“…[15][16] Thus, the minimization of the polydispersity is one of the important challenges of this synthesis route as highly polydisperse or irregular particles poses difficulties for further applications. [17][18] [19] It is widely believed and accepted that the optical properties of plasmonic nanoparticles strongly depend on the size, polydispersity and nonuniformity of the particle morphology. [20][21] [22] [23]It has also been shown that polydispersity has a strong effect on the total energy absorption and thus, on the plasmonic heat generation.…”