In the field of nanophotonics, Surface Plasmon Resonance (SPR) refers to a physical phenomenon in which the free electron gas on the surface of metals (such as gold, silver, or copper) or degenerate semiconductor materials undergoes collective coherent oscillations when driven by incident photons at specific frequencies. This resonance not only dramatically compresses and localizes optical energy within nanoscale spaces but also generates an extremely strong "near-field electromagnetic enhancement effect." When surface plasmon resonance is combined with the unique three-dimensional porous structure of aerogels, it gives rise to a "plasmonic aerogel micro-nano system" capable of manipulating light fields across multiple scales.
By in situ reducing or anchoring noble metal nanoparticles (e.g., gold/silver nanoparticles) during the sol-gel process, or by using conductive oxide aerogels doped with charge carriers that exhibit metallic-like conductivity (e.g., indium tin oxide ITO aerogels, MXene aerogels), scientists can construct dense plasmonic coupling arrays within the three-dimensional open network of aerogels.
Due to their exceptionally high porosity and tortuous nanoporous channels, incident photons scatter and interact repeatedly with these plasmonic active sites as they propagate through the material. Instead of dissipating randomly, the optical energy becomes precisely localized and amplified at the "hotspots" between nanoparticles.
This near-field electromagnetic localization mechanism offers significant advantages in photocatalysis, surface-enhanced Raman scattering (SERS), and solar photothermal conversion. For instance, in photo-catalytic water splitting or CO₂ reduction reactions, plasmonic aerogels can convert broad-spectrum sunlight into intense localized surface plasmons, generating a large number of high-energy "hot electrons." These hot electrons can directly transfer into adsorbed reactant molecules on the aerogel surface, significantly lowering the activation energy required for bond breaking.
Meanwhile, the enormous specific surface area provided by the three-dimensional porous framework of aerogels enables highly efficient diffusion and adsorption of reactant molecules, achieving a perfect integration of "localized optical field enhancement" and "high-efficiency mass transport dynamics." By tuning the size, morphology of metal nanoparticles, and the pore-size distribution of the aerogel matrix, researchers can precisely control the peak absorption wavelength of the plasmonic resonance, extending seamlessly from the visible range into the near-infrared and mid-infrared regions. This opens up a new dimension of electromagnetic manipulation for developing next-generation ultra-sensitive optoelectronic detectors and full-spectrum solar energy conversion materials.