To begin, take five milliliters of deionized water and add 10 millimolars of sodium hydroxide to it. Then add two millimolars of germanium oxide to the sodium hydroxide solution to prepare sodium germinate solution and stir the mixture at room temperature for about 30 minutes. Next, add four millimolars of zinc chloride, 0.01 millimolars of manganese nitrate, and 600 microliters of nitric acid to 22 milliliters of deionized water and stir until completely dissolved.
Now, slowly add the sodium germinate solution to the prepared solution and add one milliliter of polyethylene glycol. Then place the calibrated pH meter probe into the solution to monitor the pH value. Add ammonium hydroxide with a mass fraction of 25 to 28%to the solution drop by drop and adjust the pH to 6.0, 8.0, or 9.4.
Cover the beaker with sealing film, and stir the solution at room temperature for one hour while maintaining a constant stirring speed. Afterward, transfer the solution to a Teflon lined autoclave and place it in an electric thermostatic drying oven at 220 degrees Celsius for four hours. After completion, turn off the oven and let the system cool to room temperature before taking out the reactor.
Open the reactor slowly and transfer the reaction solution to 250 milliliter centrifuge tubes. Rinse the reactor with 40 milliliters of ethanol and transfer the ethanol to the tubes. Then vortex the solution for 30 seconds.
Centrifuge at 4, 000 G for 15 minutes at room temperature and remove the supernatant. Next, add 10 milliliters of deionized water to each tube and sonicate for five minutes to redisperse the product. Add 20 milliliters of ethanol to each tube and vortex for 30 seconds for even mixing.
Repeat the centrifugation process and discard the supernatant. Ultrasonicate the product for five minutes to disperse the product in two milliliters of methanol solution and store the sample at four degrees Celsius after sealing it with sealing film. The TEM image showed that zinc germinate manganese PLNPs with pH 9.4 were rod shaped and had an average diameter of about 65 nanometers.
The high resolution TEM images demonstrated that the nanomaterials had good crystallinity with a lattice spacing of 0.70 nanometers. The afterglow visible emission spectra of the zinc germinate manganese solution showed that the PLNPs exhibited a red shift of the main emission peak when the precursor solution changed from acidic to alkaline. Additionally, the pH value had an impact on the decay curve of afterglow intensity over time.
The photo luminescence images and afterglow images of PLNPs revealed that the solution exhibited a brighter green luminescence as the alkalinity of the solution increased.
