Probing porosity and pore interconnectivity in self-assembled TiO ₂-graphene hybrid nanostructures using hyperpolarized ¹²⁹Xe NMR

Hyperpolarized (HP) ¹²⁹Xe NMR was used to probe the porosity and interconnectivity of pores in self-assembled hybrid TiO ₂-graphene nanostructures. We have demonstrated that HP ¹²⁹Xe NMR is a powerful technique in probing any changes in porosity and interconnectivity of the pores caused by the addition of a small amount of functionalized graphene sheets (FGSs) (1% weight percent) into the network of mesoporous TiO ₂. To obtain the information on the changes in porosity and interconnectivity of the pores caused by the addition of a small amount of FGSs, a comparative study has been carried out by acquiring HP ¹²⁹Xe NMR spectra under identical experimental conditions for both pure mesoporous TiO ₂ and hybrid TiO ₂-FGSs. The HP ¹²⁹Xe NMR results from our comparative study suggest that TiO ₂ and graphene are mixed uniformly on the nanoscale and the resulting hybrid nanostructure has better channel connectivity between different domains, enhancing the transport property for Li-insertion/extraction.