Localized SPR for Pb(II) ion sensing utilizing chitosan/reduced graphene oxide nanocomposite

In this work, a simple and highly sensitive localized surface plasmon resonance (LSPR) technique had been developed for detection of Pb(II) utilizing chitosan/reduced graphene oxide (CS/rGO) nanocomposite as the sensing material. Gold nanoparticles (AuNP) had been incorporated with the nanocomposite material to induce strong LSPR responses. CS/rGO nanocomposite was coated on top of AuNP and had been utilized as active layer for Pb(II) ion sensing. The morphology and physical properties of gold nanoparticle-chitosan/reduced graphene oxide (AuNP-CS/rGO) nanocomposite was studied using field-emission scanning electron microscopy (FESEM), atomic force microscopy (AFM) and x-ray diffraction (XRD) analysis. FESEM exhibits a rough and wrinkle surface of AuNP-CS/rGO after the addition of rGO. AFM shows a higher surface roughness for AuNP-CS/rGO due to the presence of oxygen atoms in rGO where these oxygen atoms provide more sites for adsorption of Pb(II), hence enhance the sensitivity of the sensor. A good sensitivity of the LSPR sensor for detection of Pb(II) utilizing AuNP-CS/rGO was obtained which is 1.544 ppm-1 and the linearity of the sensor are 0.99 and 0.97. In stability study, AuNP-CS/rGO exhibits a good repeatability with relative standard deviation of 2% for 0.01 ppm.