2.4. Measurement of photocatalytic activity of Ag:AgCl
Photocatalytic activity of the Ag:AgCl crystals were evaluated by the degradation
of methylene blue (MB) under visible light irradiation. Typically, 4 mL of
Ag:AgCl dispersion was centrifuged to collect the particles and the particles were
re-dispersed in 2 mL of de-ionized water. Then, 2 mL of aqueous MB solution with
concentration of 20 mg/L was then added to the dispersion of Ag:AgCl. The mixture
was stirred magnetically in the dark for 45 min to reach the adsorption–desorption
equilibrium of MB molecules on the Ag:AgCl. The solution was then exposed to a
150-W Quartz halogen lamp (General Electric Co.) to trigger decomposition of the
MB molecules. Aliquots of solution (0.45 mL) were taken out at different times
and centrifuged to settle the particles. The top solution was transferred to a quartz
cuvette for monitoring the concentration of the MB molecules with a UV–Vis
spectrophotometer.