Graphite like C3N4 (g-C3N4) was synthesized facilely via the low temperature thermal condensation of melamine between 300–650°C. The results showed that the products maintained as melamine when the temperature is below 300°C. With the increase of temperature, the products were transformed into carbon nitride and amorphous g-C3N4 successively. The morphology of products was changed from spherical nanoparticles of melamine into layer carbon nitride and g-C3N4 with the increase of temperature. The photoluminescence spectra showed that the carbon nitride products have continuous tunable photoluminescence properties in the visible region with increasing temperature. With the help of steady state, transient state time-resolved photoluminescence spectra and Raman microstructural characterization, a novel tunable photoluminescence mechanism was founded systematically, which is mainly related to the two dimensional π-conjugated polymeric network and the lone pair of the carbon nitride.

By finely tuning the electrospun parameters (feeding rate of solution, working voltage and distance, etc.) and concentration of inorganic salts, various ZnAl(2)O(4) nanostructures (nanoparticles, nanonecklaces, nanofibers, nanotubes and hollow micromelts) were controllably synthesized by a single-nozzle electrospinning technique. The formation mechanisms of different ZnAl(2)O(4) nanostructures, including 'oriented attachment' mechanism, 'gas-push' mechanism, etc., were proposed to elucidate the morphology of the nanostructures and microstructure evolvement process. The morphology and microstructure of calcined electrospun nanostructures were considered to be mainly dependent on two factors, i.e. concentration of inorganic salts and size of as-prepared electrospun nanofibers. Using Ni(2+) ions as activators, broadband near infrared (NIR) emission covering 1000-1400 nm peaking at about 1176 nm was detected in Ni(2+)-doped ZnAl(2)O(4) nanostructures. The broadband NIR emission at around 1.3 μm optical communication window with a long lifetime of ~640 μs makes Ni(2+)-doped ZnAl(2)O(4) nanostructures as a promising candidate for micro/nano-broadband optical amplifiers, fibers, etc.

ZnAl 2 O 4 nanofibers and nanoparticles were in situ synthesized by electrospinning technique. Utilizing poly (vinyl pyrrolidone) (PVP) with different degree of polymerization, SEM (scanning electron microscope) results indicate that ZnAl 2 O 4 nanostructures exhibit different morphologies under the same electrospun parameters. When PVP with high molecular weight (Mw = 1,300,000) was used, the ultra-long ZnAl 2 O 4 nanofibers were obtained with an average diameter of ∼200 nm. However, while PVP with low molecular weight (K-30) was used, the ZnAl 2 O 4 changed into particle-shape with an average size of ∼100 nm. Utilizing Nd 3+ ions as the optical activator, three emission peaks centered at 905 nm, 1064 nm and 1335 nm were detected respectively in the photoluminescence (PL) spectra of ZnAl 2 O 4 :Nd 3+ nanostructures under 808 nm laser excitation. It is noticed that both the excitation wavelength (808 nm) and the emission wavelength (905 nm and 1064 nm) are located in the 700-1100 nm optical window of cells and tissues. And the cytotoxicity investigation indicates ZnAl 2 O 4 :Nd 3+ nanostructures are biocompatible with human cells, which endow their potential application as biological markers, etc.

MCM-48 nanoparticle-embedded polymer nanofibers (NPNFs) were prepared from the PVP solution containing MCM-48 nanoparticles (NPs) by the electrospinning technique. X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy-dispersive X-ray spectrometry (EDS) were used to characterize the composition and morphology of electrospun nanofibers. The results showed that the average diameter of MCM-48 NPNFs was about 500 nm. Photoluminescence (PL) and phosphorescence properties were investigated by fluorescence spectrofluorometer. MCM-48 NPNFs exhibited a bright bluegreen emission at y420 nm, followed by a long-lifetime bluegreen phosphorescence at y480 nm, which can be fitted by a biexponential decay process with lifetimes of 3.24 s and 1.22 s at room temperature. The triplet-to-singlet transition is responsible for the blue-green emission around 420 nm of the MCM materials, while the phosphorescence at y480 nm is probably due to the oxygen-related vacancies on the surface, which act as a capture trap.