Supercritical CO₂ Directional-Assisted Synthesis of Low-Dimensional Materials for Functional Applications

Supercritical CO₂ (SC CO₂ ), as one of the unique fluids that possess fascinating properties of gas and liquid, holds great promise in chemical reactions and fabrication of materials. Building special nanostructures via SC CO₂ for functional applications has been the focus of intense research for the past two decades, with facile regulated reaction conditions and a particular reaction field to operate compared to the more widely used solvent systems. In this review, the significance of SC CO₂ on fabricating various functional materials including modification of 1D carbon nanotubes, 2D materials, and 2D heterostructures is stated. The fundamental aspects involving building special nanostructures via SC CO₂ are explored: how their structure, morphology, and chemical composition be affected by the SC CO₂ . Various optimization strategies are outlined to improve their performances, and recent advances are combined to present a coherent understanding of the mechanism of SC CO₂ acting on these functional nanostructures. The wide applications of these special nanostructures in catalysis, biosensing, optoelectronics, microelectronics, and energy transformation are discussed. Moreover, the current status of SC CO₂ research, the existing scientific issues, and application challenges, as well as the possible future directions to advance this fertile field are proposed in this review.