Worldwide, billions of dollars are spent on research related to graphene, the semimetal that has also been tested for corrosion protection. A recent article provides a comprehensive overview of the synthesis of graphene by traditional and modern methods as well as key requirements for good corrosion protection.
By András Gergely
In the past there have been many attempts to achieve corrosion protection of metals with molecular-tight atomic thin layers, with graphene presumed to be the most efficient of all elements and carbon allotropes to date. Although highly and finely tuneable, electrical conductivity is the main and most precious feature exploited in the majority of applications in fields such as electronics, photocatalysis and electrocatalysis.
Corrosion protection of metals favours physical separation and electrical insulation which are based on low electrical conductivity to the basal plane and high chemical resistivity, the latter duo being the basis for durable and excellent protection by gas-impermeable graphene sheets. A recent article, published in Corrosion Reviews, covers numerous studies to give readers a wide overview on the synthesis and modification of single and multiple-layer graphene, used either as neat films or in composite layers and coatings.
The quality of graphitic lattice and the extent of exfoliated graphene sheets are key parameters for effective corrosion protection, as well as their dispersity and distribution without folding and wrinkling. Special applications may require neat graphene films, but in general strong adherence to metal surfaces necessitates graphene filler based composites, allowing long-term reliable high protection performance. Atomic layer deposited films and composite coatings with inorganic and hybrid binders provide maximum performance, reliability and durability at micro- and macro-scales.
Modification and functionalisation of graphene are generally both aimed at binder compatibilization, or increasing degree of water repellence, hydrophobicity and super-hydrophobicity. For further development, a partial or complete substitution of graphene with boron nitride (BN) and Molybdenum disulfide (MoS2) is also a viable option. The unparalleled barrier nature of graphene-loaded composites can also be achieved with multiple functionalities in ways leading to them to behave like smart coatings.
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