Characterisation and Modification of Pristine Crystalline Fullerites for Sensors

This work explores the functionalisation of fullerites with metal nanoparticles to exploit their potential as a hydrogen sensing material. Fullerites are ideal materials for gas adsorption due to the porosity and high surface area. By introducing transition metals such as iridium and palladium covalently, we create a sensory material, as these metals have a natural affinity to hydrogen. 
This investigation is an ongoing detailed study aimed at controlling the growth of fullerites through careful control of the experimental parameters. As a result we have an understanding of growth mechanism and can report the controlled growth of fullerite rods with true nanoscale dimensions.
High purity single crystal fullerites with uniform dimensions are synthesized by a rapid and facile approach which can be completed over a timescale of typically a few minutes. Our initial studies demonstrated defect free LLIP grown rods with a hexagonal cross-section and novel faceted tips (Figure a). The rods typically have a length:diameter ratio of 10:1 with diameters typically ~500 nm. The majority of the rods have a diameter between 0.2 - 0.8 μm and length of 4 - 8 μm.

The growth of rods of 50 nm diameter has been achieved thus representing an order of magnitude decrease in scale of the structures obtained using this method. We can also obtain other crystalline structures with large area:thickness ratios as shown in Figure b.

The fullerite structures were characterised using spectroscopy techniques of Fourier transform infrared spectroscopy, Raman spectroscopy, ultra-violet/visible/near-infrared absorption spectroscopy and photoluminescence spectroscopy.
With respect to the use of such structures in nanoelectronic devices we report initial trials in which pristine fullerites have been incorporated into polymer photovoltaic devices and demonstrated to improve device efficiency.
A large photoconductivity exists under light illumination, making these rods a possible candidate for optical switch.