Green synthesized silver nanoparticles decorated on nanostructured porous silicon as an efficient platform for the removal of organic dye methylene blue

In the present work, nanostructured porous silicon (nPSi) thin films were used as a substrate for the deposition of green synthesized silver nanoparticles (AgNPs). Different kinds of AgNPs were green synthesized by using Peumo extract and changing AgNO₃ concentration. UV-vis spectroscopy confirmed the success of the synthesis, and TEM characterization showed AgNPs with a like-spherical shape and an average diameter, which ranges from 4 to 25 nm, depending on the AgNO₃ concentration used. Then, AgNPs were introduced into the nPSi layer with a mean pore diameter of 46 nm and 75% of porosity by capillary suction. Hybrid layers nPSi/AgNPs were characterized by SEM, XRD, and RBS, confirming that AgNPs were introduced into nPSi layers. The catalytic activity of the hybrid layer in the reduction of organic dyes in water was studied using methylene blue (MB) as a model dye. Experimental results showed a high catalytic activity in comparison with other hybrid systems. The kinetic reduction could be fitted to the first-order equation obtaining the best degradation rate of 8.6 min⁻¹ with AgNPs synthetized with 2 mM of AgNO₃. In addition, the reusability of these layers was demonstrated after five cycles, showing promising results for their use in wastewater management.