Two-step process for synthesizing flower-like silver nanoparticles by wet-chemical method

•Flower-like AgNPs are facilely synthesized with two-step wet-chemical method.•Effect of gum arabic and HNO3 on morphology of AgNPs is intensively investigated.•The growth mechanism of AgNPs is analyzed. Flower-like silver nanoparticles (F-AgNPs) are facilely synthesized with two-step wet-chemical method. In the first step, ho leaf extracts reduce AgNO3 to form spherical AgNPs. In the second step, F-AgNPs are synthesized from spherical particles. The effect of gum arabic and HNO3 on morphology of F-AgNPs is intensively investigated. The reduction and oxidation provide a trade-off between aggregation and detachment of Ag atoms on the surface, while the structure-directing agent boosts preferential growth, contributing to formation of F-AgNPs with different shapes. Our results pave an alternative way for synthesizing AgNPs with specific shapes and advancing applications.