The optical properties of zinc (hydr)oxide and its porous composites with 2% and 5% graphite oxide (GO), thus forming ZnGO-2 and ZnGO-5, are investigated using reflectance spectroscopy and two-photon fluorescence (TPF) imaging. The bandgap energies for the Zn(OH)(2), ZnGO-2, and ZnGO-5 samples are determined to be in the range between 2.88 and 3.60 eV. The size of light-emitting regions (~from 4.5 to 45 μm) and pore size (~from 20 to 255 μm) are measured using the TPF imaging technique.

Time-resolved photoluminescence is used to determine carrier recombination through radiative and nonradiative processes in zinc hydroxide Zn(OH)(2) and its porous composites with graphite oxide (GO). The decay times, measured by a streak camera, are found to be larger for zinc hydroxide (~1215±156 ps) than its composites (~976±81 ps for ZnGO-2 and 742±59 ps for ZnGO-5), but no significant changes in rise times (from 4.0 to 5.0 ps) are recorded. The dominant mechanism for the radiative process is attributed to free carrier recombination, while microporous networks present in these materials are found to be pathways for the nonradiative recombination process via multiphonon emission.