One-pot green synthesis of Ag nanoparticle-decorated reduced graphene oxide composites: effect of Ag/graphene oxide volume ratio and its demonstration as low-voltage on-chip photodetector

We present one-pot synthesis of silver nanoparticle-decorated reduced graphene oxide (AgNP-rGO) composite by utilizing ascorbic acid as a green reduction agent. The effect of volume ratio between Ag(NH3)(2)OH complex solution and GO solution was studied. High content of Ag volume seems to slower down the reduction of GO, hence providing high nucleation sites for the Ag ions to be reduced to nanoparticles with much higher density. Meanwhile, due to high reduction rate of GO at low content of Ag volume, it produces less density of nanoparticles with larger particle size. The composite was successfully demonstrated as a low-voltage on-chip photodetector. The presence of high-density AgNPs on rGO results to fast response (393 nA/s) and recovery rate (399 nA/s) with excellent cyclic stability even at low biasing voltage of 1 [V] due to the effective localized plasmon resonance of AgNPs. The detectivity and responsivity remarkably increase with the densities of AgNPs and the biasing voltages, where these values can increase from 3.58 x 10(5) cm Hz(1/2) W-1 and 2.2 x 10(-6) A/W at 1 [V] up to 2.12 x 10(8) cm Hz(1/2) W-1 and 3.8 x 10(-2) A/W at 20 [V], respectively, for the sample with Ag volume of 75%.