In collaboration with Milo Shaffer (Imperial College London), we investigate the preparation and uses of metal (Cu), metal oxide (ZnO, Cu2O, CuO) and layered zinc hydroxide (LZH) nanomaterials. We have developed preparations from well-defined organometallic reagents, using low-temperature conditions and producing colloidal solutions/inks of the nanomaterials, soluble in common organic solvents and even in water. To make ZnO or LZH, the synthesis exploits the controlled hydrolysis of organo-zinc reagents with sub-stoichiometric amounts of zinc carboxylate/phosphinate complexes to make small (3-4 nm), highly crystalline ZnO nanoparticles or exfoliated LZH nanosheets.
Our team also investigates the formation mechanisms for these well-defined nanomaterials from solutions of organometallic precursors. As part of this research, we discovered a series of zinc cluster complexes present during the formation of colloidal zinc oxide nanoparticles. By using 31P NMR spectroscopy, in combination with single crystal X-ray diffraction experiments, we identified organometallic clusters comprising 4, 6, 9, 11 zinc centres which are progressively implicated during ZnO nanoparticle synthesis.
We also developed routes to prepare ultra-small, monodisperse Cu and Cu2O nanoparticles from organo-copper precursors; redox cycling between Cu(0) and Cu(I) states is feasible by exposure of solutions to the air or by treatment with low-pressures of hydrogen (3 bar). The new nanomaterials, both zinc and copper containing, are under investigation as catalysts (carbon dioxide hydrogenation), photoactive materials and in polymer composites.