Supersonic Cold Spraying for Energy and Environmental Applications: One‐Step Scalable Coating Technology for Advanced Micro‐ and Nanotextured Materials

Supersonic cold spraying is an emerging technique for rapid deposition of films of materials including micrometer‐size and sub‐micrometer metal particles, nanoscale ceramic particles, clays, polymers, hybrid materials composed of polymers and particulates, reduced graphene oxide (rGO), and metal–organic frameworks. In this method, particles are accelerated to a high velocity and then impact a substrate at near ambient temperature, where dissipation of their kinetic energy produces strong adhesion. Here, recent progress in fundamentals and applications of cold spraying is reviewed. High‐velocity impact with the substrate results in significant deformation, which not only produces adhesion, but can change the particles' internal structure. Cold‐sprayed coatings can also exhibit micro‐ and nanotextured morphologies not achievable by other means. Suspending micro‐ or nanoparticles in a liquid and cold‐spraying the suspension produces fine atomization and even deposition of materials that could not otherwise be processed. The scalability and low cost of this method and its compatibility with roll‐to‐roll processing make it promising for many applications, including ultrathin flexible materials, solar cells, touch‐screen panels, nanotextured surfaces for enhanced heat transfer, thermal and electrical insulation films, transparent conductive films, materials for energy storage (e.g., Li‐ion battery electrodes), heaters, sensors, photoelectrodes for water splitting, water purification membranes, and self‐cleaning films.