Laser-Reduced Graphene: Synthesis, Properties, and Applications

Laser reduction of graphene oxide has attracted significant interest in recent years, because it offers a highly flexible, rapid, and chemical-free graphene fabrication route that can directly write on almost any solid substrate with down to sub-micrometer feature size. Laser-reduced graphene (LRG) is explored for various important applications such as supercapacitors, sensors, field effect transistors, holograms, solar cells, flat lenses, bolometers, thermal sound sources, cancer treatment, water purification, lithium-ion batteries, and electrothermal heaters. This contribution reviews most recent research progress on the aspects of fabrication, properties, and applications of LRG. Particular attention is paid to the mechanism of LRG formation, which is still debatable. The three main theories, including the photochemical process, the photothermal process, and a combination of both processes, are discussed. Strategies for tuning the properties and performance of LRG, such as the laser parameters, chemical doping, structure modulation, and environment control, are highlighted. LRGs with better performance including smaller feature size, higher conductivity, and more flexible morphology design in both 2D and 3D formats will offer tremendous opportunities for advancement in electronics, photonic, and optoelectronic applications.