application of carbon quantum dots in inhibiting copper corrosion: the effect of different layer deposition techniques

Abstract: corrosion is an attack on metallic material by reaction with its environment [1]. corrosion is a spontaneous phenomenon which causes huge damage to industries worldwide [2]. according to the reports, the current global cost of corrosion is estimated to be us$2.5 trillion, which is equivalent to 3.4% of the global gdp (gross domestic product) (2013). by using available practical corrosion control, it is estimated that savings of between 15% and 35% of the cost of corrosion could be realized, between us$375 and $875 billion annually on a global basis [3]. the use of inhibitors is one of the best methods of corrosion control, which is discussed in this article, due to its advantages such as cost-effectiveness and ease of use in industry. most corrosion inhibitors are expensive and environmentally hazardous chemicals, so the research on environmentally friendly inhibitors is a new field of interest. carbon quantum dots (cqds) are new class of fluorescent carbon nanoparticles family that are usually less than 10 nanometers long [4]. these materials are a new class of zero-dimensional nanomaterials that have many functional groups and good solubility in water [5]. herein, novel cqds have been prepared from pekmez (doshab) using a facile hydrothermal method. cqds adsorption film was formed on copper substrate as a barrier that could prevent transportation of corrosive particles. for this purpose, three different concentrations of cqds were made to investigate (1%, 2%, 5%). to investigate the inhibitory effect of quantum dots, three different methods as self-assembling, coating and directly adding inhibitor to the corrosive media of nacl 3.5% were used. in each method, cqds deposit on the surface on coper metal automatically. the inhibition performance of purposed methods was compared through electrochemical impedance spectroscopy (eis), linear sweep voltammetry (tafel plots) and ft-ir methods. the results showed that the coating and self-decoration methods are more effective than the direct addition of the inhibitor to the corrosive environment. also, coating method showed even better efficiency in lower concentrations of cqds than self-assemble method for long periods of time.