Experimental and theoretical investigation of ligand effects on the synthesis of ZnO nanoparticles

ZnO nanoparticles with highly controllable particle sizes(less than 10 nm) were synthesized using organic capping ligands in Zn(Ac)2 ethanolic solution. The molecular structure of the ligands was found to have significant influence on the particle size. The multi-functional molecule tris(hydroxymethyl)-aminomethane (THMA) favoured smaller particle distributions compared with ligands possessing long hydrocarbon chains that are more frequently employed. The adsorption of capping ligands on ZnnOn crystal nuclei (where n = 4 or 18 molecular clusters of(0001) ZnO surfaces) was modelled by ab initio methods at the density functional theory (DFT) level. For the molecules examined, chemisorption proceeded via the formation of Zn...O, Zn...N, or Zn...S chemical bonds between the ligands and active Zn2+ sites on ZnO surfaces. The DFT results indicated that THMA binds more strongly to the ZnO surface than other ligands, suggesting that this molecule is very effective at stabilizing ZnO nanoparticle surfaces. This study, therefore, provides new insight into the correlation between the molecular structure of capping ligands and the morphology of metal oxide nanostructures formed in their presence

Environmental Applications of Semiconductor Photocatalysis

X1113435Nsciescopu

A high-resolution optically addressed spatial light modulator based on ZnO nanoparticles

This is the final version. It was first published by NPG at http://www.nature.com/lsa/journal/v4/n3/full/lsa201532a.htmlAn optically addressed spatial light modulator (OASLM) can modulate the wavefront of a read light by displaying a phase pattern or hologram configured by the intensity distribution of a write light. Using ZnO nanoparticles (NPs) as a novel photoconductor, a high resolution OASLM is fabricated. ZnO NP suspension is spin coated on the ITO coated glass substrate and annealed to form a photosensitive layer. The device is characterized electrically and optically. The device is operated at low driving voltages in the transmission mode. Updatable recording of diffraction grating up to 825 lp mm-1 with the diffraction efficiency (DE) of 0.05% and binary holograms with the pixel size from 2 ?m down to 0.72 ?m are demonstrated using a write laser of 405 nm wavelength and a read laser of 635nm wavelength.This work was supported by the EPSRC through the Platform Grant for LC Photonics (EP/F00897X/1)