Nano ZnO, Cu-doped ZnO, and Ag-doped ZnO assisted generation of light from imidazole

Abstract

• ZnO surface enhances π electron delocalisation, lowers HOMO–LUMO energies due to adsorption. • Energy gap of MNDI-Cu–ZnO lowers compared to those of pristine ZnO and thus red shift. • Energy gap of MNDI-Ag–ZnO larger compared to that with ZnO and thus blue shift. • Shortening of decay time of MNDI indicates charge transfer from MNDI to nanocrystals. • ∆ G et −1.23 eV indicates thermodynamic feasibility of electron transfer process. A sensitive 2-(4-methoxyphenyl)-1-(naphthalene-1-yl)-4,5-diphenyl-1H-imidazole (MNDI) fluorescent sensor for nanoparticulate ZnO has been designed and synthesized. The nanocrystalline ZnO, Cu-doped ZnO, and Ag-doped ZnO have been synthesised by sol–gel method and characterized by powder X-ray diffraction, scanning electron microscopy(SEM), UV–vis diffuse reflectance, photoluminescence and life time spectral studies. All the synthesized nanoparticles display violet emission due to charge carrier-recombination. The synthesized sensor emission is enhanced by nanocrystalline pristine ZnO but is suppressed by Cu-doped ZnO and Ag-doped ZnO nanoparticles. The suppression of fluorescence is more by copper than by silver doping.