Chemically reduced silver nanoparticles: preparation and applications

By virtue of their unique physiochemical properties, silver nanoparticles (AgNPs) have attracted enormous research interest for versatile applications. It is critical to study the effect of the microstructure – for example, the shape and the size of AgNPs – on their performance. Herein, AgNPs with varying shapes and sizes were synthesized by varying the manner that the reducing agent sodium borohydride (NaBH₄) was added (i.e. multistep and one-step reduction methods) and then were studied for photocatalysis of dyes and electrocatalytic oxidation of glucose. The results showed that triangular AgNPs, spherical AgNPs or a mixture of triangular- and spherical-shaped AgNPs was obtained from the multistep reduction method, whereas only spherical-shaped AgNPs were yielded from the one-step reduction method. The sizes could be manipulated by changing the concentrations of the reagents or the reaction temperature. The triangular-shaped and smaller-sized AgNPs were more effective for photocatalysis of dyes, and the degradation percentage of methylene blue was enhanced to 95% for the silver (Ag)–titanium dioxide (TiO₂) complex from 50% for pure titanium dioxide. Moreover, the spherical-shaped AgNPs with a smaller size could effectively detect glucose at a very low concentration of 5–10 mM with an excellent glucose tolerance.