Electrochemical strategy for grown ZnO nanoparticles deposited onto HY zeolite with enhanced photodecolorization of methylene blue: Effect of the formation of SiOZn bonds

Nanoparticles of electrogenerated zinc-supported HY zeolite (EGZnO/HY) catalyst were prepared by a simple electrochemical method. The interaction between zinc species and HY support during the electrolysis was found to affect the EGZnO/HY structure. In addition to the formation of EGZnO nanoparticles (<30 nm in size) that distributed on the surface of HY support, an isomorphous substitution of Al with Zn also occurred in the aluminosilicate framework to result in a SiOZn bonds. The photoactivity of EGZnO/HY was tested on the decolorization of methylene blue (MB). An amount of 0.375 g L−1 of 1 wt% EGZnO/HY was found to be the optimum dosage for 10 mg L−1 MB, which resulted in 80% of maximum decolorization after 6 h of contact time at pH 3 under fluorescent light (420 nm). Increasing the EGZnO loading led to additional formation of SiOZn bonds and lessened the number of EGZnO nanoparticles, which then reduced the photodecolorization percentage of MB.The photocatalytic reaction was follows the first-order Langmuir–Hinshelwood model, and gives partially mineralization. The photocatalyst was still stable after five cycling runs with no Zn leaching.

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► Electrochemical method generates the growth of ZnO less than 30 nm in size.
► Isomorphous substitution of Al with Zn occurred during the electrolysis.
► A new structural model for EGZnO/HY is proposed.
► SiOZn bonds were formed as proven by MAS NMR, XPS, and IR.
► 1 wt% EGZnO/HY exhibited the best performance for the photodecolorization of MB.