Electrochemiluminescence from hydrophilic thin film Ru(bpy)32+-modified electrode prepared using natural halloysite nanotubes and polyacrylamide gel

Because Ru(bpy)32+-modified electrodes are often used in aqueous condition, the development of a hydrophilic modified electrode is of critical importance. Herein a hydrophilic, thin film Ru(bpy)32+-modified electrode is successfully developed using polyacrylamide gel to embed halloysite nanotubes on the electrode surface which is used to adsorb Ru(bpy)32+ by cation-exchange. X-ray photoelectron spectroscopy demonstrates the formation of the film on an electrode and the high adsorbing capacity of the halloysite nanotubes toward Ru(bpy)32+. The different electrochemiluminescence (ECL) behaviors of the electrode using nitrilotriacetic acid and tripropylamine, as co-reactants, illustrate the hydrophilic character of the modified electrode. Contrary to the previous works, the addition of carbon nanotubes into the modified electrode film leads to a decreased ECL emission, due to the reduction in the porosity of the film, which hinders the diffusion of the analyte.