Sunlight-driven synthesis of anisotropic silver nanoparticles

•Sunlight is used to prepare anisotropic silver nanoparticles.•High concentration of citrate promotes the formation of pyramidal silver nanoparticles during photoinduced reaction.•UV light from sunlight plays an important role in shape conversion.

Photoinduced shape conversion of silver nanoparticles was realized using sunlight. The silver seeds were transformed to silver nanoprisms under sunlight when the concentration of citrate was low (⩽5.0 × 10−4 M). Nevertheless, sunlight converted the obtained silver nanoprisms to silver nanodecahedrons when the concentration of citrate in reaction system was increased. It was found that the ultraviolet light from sunlight played a vital role in the shape conversion from nanoprism to nanodecahedron. Lighting power density did not influence the shape conversion except for reaction rate. Besides, the silver nanodecahedrons were synthesized in the mixed solution of AgNO3 and citrate in absence of silver seeds through irradiation by simulated sunlight. The mechanism on the sunlight induced synthesis of silver nanoparticles was discussed. Anisotropic silver nanoparticles including nanoprisms and nanodecahedrons were obtained through controlling the citrate concentration and irradiation time by sunlight from green light source.

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