Fig. 5. UV-vis spectra of the NaOH/HCl cycled particles. (a) The starting solution is the material 44 h after start of growth. NaOH-1 and HCl-1 is the solution after the first addition of NaOH and subsequent first addition of HCl, respectively. (b) Spectra comparing the solution after the first HCl addition to the subsequent addition of the second NaOH and then the second HCl. (c) Spectra comparing the material after the second HCl addition to the subsequent third NaOH, third HCl, and fourth NaOH additions. (d) Spectra of all the solutions after NaOH additions and (e) spectra of all the solutions after HCl additions.
