Facile Approach to Fabricating Stretchable Conductors by Decorating Cheap Reduced Graphene Oxide with Silver Nanocrystals in Loofah Sponge Fibers

Reduced graphene oxide (rGO) is labeled as "bargain graphene" because of its lower cost in industrial production and is widely used as the conductive filler of the tensile conductor. Generally, rGO is fabricated via reduction from graphene oxide (GO), so an oxygen group defect and hanging atoms on its fringe could be designed and controlled by atomic adsorption with other heteroatoms. In this work, an activated conductive network was fabricated by in situ decorating rGO with silver nanocrystals (AgNCs) in the inner surface of a one-dimensional bundled microtunnel of loofah sponge (LS) fibers. The polydimethylsiloxane (PDMS)/LS–rGO–AgNC composites exhibited a seepage threshold of 0.37 wt % with an electrical conductivity of 0.26 S/m under 1.08 wt % of AgNC loading. This outstanding performance was attributed to AgNC decoration in the fringe of rGO in an activated conductive network, whose integrity was maintained through AgNCs. As a result, the composite as a flexible strain sensor exhibited stable strain sensing ability. Furthermore, the activation mechanism of a conducting network in the composites was preliminarily elucidated based on SEM analysis and density functional theory (DFT) calculations. It can be proved that the hanging carbon atom other than a carboxyl group on the edge of the rGO nanosheet could form strong chemical adsorption with a Ag atom, so that the AgNCs were effectively modified on the edge of the rGO.