Nacre-inspired fabrication of robust and flexible photothermal protective films using a coordination-crosslinking self-assembly strategy

Multifunctional photothermal protective films are novel photothermal-conversion materials that efficiently harvest and utilize solar energy. They also require excellent stability and durability. However, the poor toughness, loose structure, and weak shielding performance of these films limit their applications in photothermal conversion and metal protection. Inspired by the delicate microstructure of nacre , which exhibits excellent strength and barrier protection performance, a coordination-crosslinking self-assembly strategy is proposed herein that realizes a bio-phytic acid–silane–graphene oxide (bio-PSGO) metal-protective film with nacre-mimetic structures. The self-assembled bio-PSGO film exhibits good flexibility, excellent photothermal-conversion efficiency (93.9 %), outstanding protective performance, and water-desalination ability under natural sunlight irradiation. The coordination-crosslinking self-assembly process is simple and spontaneous, and it quickly assembles a complete thin film in an aqueous system. Nacre-like structured bio-PSGO films are easily obtained on the surfaces of metal substrates, such as iron, copper, zinc, magnesium, aluminum , and nickel. Metal ions released from metal materials promote the self-assembly of films via coordination crosslinking with PSGO nanosheets ; meanwhile, the thermally conductive metal materials quickly transfer the heat generated in the photothermal-conversion process, synergistically improving the photothermal efficiency of the system. The proposed strategy designs robust and flexible materials that simulate the lamellar microstructure of nacre, which can be applied in flexible wearable devices and sensors, energy supply, metal protection, seawater desalination, solar thermal de-icing, and aerospace technologies.