Probing Porosity and Pore interconnectivity in Self-Assembled TiO2-Graphene Hybrid Nanostructures Using Hyperpolarized 129Xe NMR

Hyperpolarized (HP) Xe-129 NMR was used to probe the porosity and interconnectivity of pores in self-assembled hybrid TiO2 graphene nanostructures. We have demonstrated that HP Xe-129 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 TiO2. 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 Xe-129 NMR spectra under identical experimental conditions for both pure mesoporous TiO2 and hybrid TiO2-FGSs. The HP Xe-129 NMR results from our comparative study suggest that TiO2 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.