Absorption spectra were recorded on an Agilent 8453 UV–visspectrophotometer (Agilent Technologies, Santa Clara, CA, USA).Transmission electron microscopy (TEM) measurements weremade on a JEM-2010 (JEOL Co., Japan). The associated point andlinear resolutions were 0.23 nm and 0.14 nm, respectively, andthe operational accelerating voltage was 200 kV. The TEM samples were prepared by placing a drop of colloidal solution on a carbon-coated copper grid and dried at room temperature. X-ray diffraction(XRD) spectra of AgNPs were obtained by a Bede D1 System High resolution X-ray diffraction (Bede Co., UK). The XRD samples were prepared by dropping high concentrated colloidal solution on an ITO (Indium tin oxide) conducting glass and drying for 10 h in air at room temperature. The photographs were taken with a Canon 530Adigital camera. HJ-6 magnetic stirrer hotplate (Huapuda Teaching Instrument Co., Changzhou, China) was used in the preparation of the AgNPs.