Preparation and investigation of electrical conductivity of silver nanoparticle films on the paper substrate

Abstract

This paper reported the preparation of silver nanoparticles (Ag NPs) by the chemical protection-reduction method. This process was performed in an aqueous phase with a mixture consisting of silver nitrate (AgNO3), hydroxypropyl methylcellulose (HPMC), sodium borohydride (NaBH4), and hydrazine (H2N-NH2). The prepared Ag NPs were characterized by transmission electron microscope (TEM) and ultraviolet-visible (UV-Vis) spectroscopy. The TEM images indicated that Ag NPs had high purity with the size of 20‒50 nm. The Ag NPs solution strongly absorbed around 420 nm and displayed brown color under visible light. The stability of the Ag NPs solution was maintained after 60 days of storage. The conductivity of the Ag NPs solution depended on the initial concentration of AgNO3, HPMC content, type of reducing agent, pH environment, and also the order of using reducing agents in the prepared process. Next, the Ag NPs solution was coated to form a film on the paper substrate. The thickness of the obtained film was about 49.2 µm according to the analysis results from the Leica 2500 DM microscope and its conductivity was investigated by the four-point probe method. The film could conduct the electricity and light up LEDs when using a 9 V DC power source. The obtained results demonstrated that the prepared Ag NPs would have a potential application as conductive inks in electrical plastic devices.