Effect of pH and Concentration of Dopamine Solution on the Deposited Polydopamine Film and the Prepared Graphene-like Material

Abstract

In this study, according to the acquired polydopamine deposition rates, polydopamine films with equal thickness were prepared under different conditions on SiO2 substrates. Subsequently, we investigated the influence of dopamine solution pH and concentration on the formation of surface aggregates of the deposited polydopamine films. Assumptions were made to explain how pH and concentration execute their effects. Based on the optimized parameters, a continuous and smooth polydopamine film with a thickness of about 14 nm and a roughness of 1.76 nm was fabricated on a silicon dioxide substrate, through the deposition for 20 minutes in a dopamine solution with a concentration of 1.5 mg/mL and a pH of 8.2. The prepared polydopamine film was then employed as a precursor and subjected to a high-temperature process for the carbonization and graphitization of the film. Raman spectroscopy analysis indicated that the resulting graphene-like film had fewer structural defects in comparison with previous works and the results of XPS indicated that most of the carbon atoms were bound into the cross-linked honeycomb lattice structure. The prepared graphene-like material also exhibited high electrical conductivity and satisfying mechanical elasticity.