▎ 摘　　要

A novel NH3 gas sensor based on reduced graphene oxide sheets (rGO) with uniformly decorated silver nanoparticles (AgNPs) on its surface is presented in this work. The aqueous solution containing silver nitrate, gelatin and graphene oxide (GO) is exposed to acoustic energy to reduce the silver nanoparticle on rGO sheets. FESEM image and EDX spot analysis show that an ultrafine spherical AgNPs with the size of about 20-30 nm are uniformly distributed on the rGO sheets. Small Raman shift of centered peaks at 1960 cm(-1) indicate the decoration of AgNPs on rGO. The UV-vis absorption peaks show a red shift toward visible spectrum from 267 nm for rGO to 459 nm for rGO decorated with AgNPs. The AgNPs/rGO nano composite as an active layer over the Cr/gold interdigited electrode is fabricated using lithography technique and are tested using a semi-automatic static set up. The sensitivity of the AgNPs/rGO is about 5.8 for 250 ppb of NH3 gas detection. While this sensor shows reproducible, stable and fully recoverable response, its limit of detection (LOD) for NH3 gas is 100 ppt. The response and recovery times are 76 and 84 s respectively. The sensor exhibits an even better sensitivity of about 1.7 times for ammonium gas detection at room temperature when it is expose to visible light of 10 mW cm(-2) (blue LED) which is believed to be due to the surface plasmon resonance (SPR) and spillover effects.