Experimental and Theoretical Studies on Corrosion Inhibition of Niobium and Tantalum Surfaces by Carboxylated Graphene Oxide.

Valbonë Mehmeti,Fetah I Podvorica

doi:10.3390/ma11060893

Abstract

The corrosion of two different metals, niobium and tantalum, in aqueous sulfuric acid solution has been studied in the presence and absence of carboxylated graphene oxide. Potentiodynamic measurements indicate that this nanomaterial inhibits corrosion due to its adsorption on the metal surfaces. The adsorbed layer of carboxylated graphene hinders two electrochemical reactions: the oxidation of the metal and the transport of metal ions from the metal to the solution but also hydrogen evolution reaction by acting as a protective barrier. The adsorption behavior at the molecular level of the carboxylated graphene oxide with respect to Nb, NbO, Ta, and TaO (111) surfaces is also investigated using Molecular Dynamic and Monte Carlo calculations.

Highlights

IntroductionMetals are prone to oxidation when exposed to different aggressive solutions in the course of industrial cleaning or other diverse treatments (acid pickling, descaling and cleaning)
Metals are prone to oxidation when exposed to different aggressive solutions in the course of industrial cleaning or other diverse treatments. the use of paints and polymers offers a simple approach to decrease the effect of corroding species on the surface, the major drawbacks of this method are the weak interactions among the metal surface and the coating layer so the physical organic barrier is deteriorated after a short time of exposure [1]
The use of paints and polymers offers a simple approach to decrease the effect of corroding species on the surface, the major drawbacks of this method are the weak interactions among the metal surface and the coating layer so the physical organic barrier is deteriorated after a short time of exposure [1]

Summary

Introduction

Metals are prone to oxidation when exposed to different aggressive solutions in the course of industrial cleaning or other diverse treatments (acid pickling, descaling and cleaning). Density Functional Theory (DFT), as a powerful technique for performing calculations on many bodied systems, permits the correlation between the adsorption ability of the inhibitor molecule on the metal surface and its electron donating tendency that is expressed by the value of EHOMO. Higher values for this orbital suggest an increasing donor-acceptor interaction between the inhibitor molecule and the vacant d-orbitals of the metal surface atoms [19,20]. Molecular dynamics [24,25] and Monte Carlo [26] simulation are used to evaluate the interaction between the Nb (111), NbO (111), Ta (111) and TaO (111) and carboxylated graphene

Experimental Section

Monte Carlo Simulations

Adsorption Energy and Radial Distribution Function

Potentiodynamic Polarization

Molecular Dynamics

Conclusions