Application of reduced graphene oxide-based actuators for real-time chemical sensing of liquid and vapour phase contaminants

Abstract

Real-time detection of contaminants dissolved in a liquid medium is critical for various technological and industrial operations. Here, we have demonstrated the possibility of employing reconstructed layered material-based responsive membranes for the in situ detection of chemical contaminants in the liquid phase. A bilayer membrane prepared by sequential vacuum filtration of reduced graphene oxide (r-GO) and agar (r-GO/agar) displayed remarkable responsiveness towards the presence of solvent vapours in their surrounding atmosphere. The shape-morphing property of the r-GO/agar membrane is attributed to unequal changes in the mechanical properties of the individual components. Rectangular strips of the bilayer membrane also displayed shape-transforming properties inside the liquid medium. Depending upon the chemical nature of the molecules, inside the liquid medium, the strips of r-GO/agar membrane bend at a definite speed to adopt a coil-like shape. The original shape of the strip is easily recovered after dipping in water or drying in air. The bending angle and the response time of the r-GO/agar strips were found to be sensitive towards trace amounts of impurities present in the solvent system, which can be exploited for the detection of contaminants in the liquid phase, like trace amounts of water molecules dissolved in acetone or different alcohol molecules dissolved in toluene.