Unidirectional electron transport from graphitic-C3N4 for novel remote and long-term photocatalytic anti-corrosion on Q235 carbon steel

Graphitic carbon nitride (g-C3N4) has been considered as a candidate for anti-corrosion material owing to its barrier property and photoelectrochemical cathodic protection. However, the related mechanisms remain obscure and are not fundamentally investigated. Herein, g-C3N4 coating on Q235 CS plate matrix can be simply made via conductive adhesive, which helps to achieve scalable production and high cost-effectiveness. It can also ensure the unidirectional transfer of excited electrons from g-C3N4 to metal to prevent the consumption of free electrons on metal and reduce Fe2O3 onto Fe. During the photocatalytic anti-corrosion process, the electron holes were simultaneously consumed via oxidizing water to achieve the balance between electron and hole transport. By combining theoretical calculation and experimental analysis, the anti-corrosion mechanisms of g-C3N4 were systematically investigated. g-C3N4 displayed superior long-term and remote anti-corrosion properties, especially for remote and difficult-to-reach areas, which will make it become a new generation of anti-corrosion 2D material with promising performance.