“Superblacks”optical materials are capable of absorbing nearly all incident light across a broad range of wavelengths and often exceed 98% absorbance. They are inspired by the theoretical concept of a perfect black body—an idealized object that absorbs and re-emits all electromagnetic radiation according to its temperature, as described by Kirchhoff’s and Planck’s laws. Scientists have long desired to approximate it for applications where stray reflection or partial transmission compromises performance. In high-precision telescopes, superblacks suppress unwanted glare that could obscure faint celestial signals; in thermal camouflage, they mask heat signatures; in solar energy harvesting, they enable near-total light capture for conversion into heat or electricity. However, despite decades of research, the availability of materials that can reach such extreme absorptance remains very limited, and the pathways to fabricate them are often rigid, costly, or material-specific. Current state-of-the-art designs rely heavily on precisely engineered nanostructures—vertically aligned carbon nanotube (CNT) forests, needle-like metallic arrays, or sophisticated biomimetic patterns inspired by moth eyes or butterfly wings. These architectures work by trapping photons within a maze of elongated or tapered features, which force multiple scattering events until the light is dissipated as heat. However, this approach demands high-temperature growth, vacuum deposition, or harsh chemical environments that exclude many promising absorbers, such as sensitive metal oxides or conductive polymers. Even when fabrication succeeds, these methods often anchor the absorber to a rigid substrate which can restrict scalability and shaping options. Moreover, the designs are tuned for a small subset of materials and trying to switch to a different absorber often requires re-engineering the structure from scratch.
To this account, new research paper published in Advanced Materials and conducted by Dr. Li Guangyong , Dr. Wang Leyi , Dr. Ji Xiaofei , and led by Professor Zhang Xuetong from the Suzhou Institute of Nano-tech and Nano-bionics（SINANO）, Chinese Academy of Sciences and (also visiting Professor at the Division of Surgery & Interventional Science, University College London), the researchers developed a universal strategy for creating superblack materials by suspending a wide variety of light‐absorbing nanoparticles within an ultra‐low‐reflective silica aerogel matrix. This aerogel, with a refractive index close to air and nanometer‐scale building blocks, minimizes both surface reflection and backscattering, allowing absorbance to exceed 99% across broad spectral ranges. Their new method works for more than a hundred types of nanoparticles—metals, semiconductors, polymers, and hybrids—while preserving additional functionalities such as magnetism, catalytic activity, and hydrophobicity. The resulting materials are lightweight, mechanically robust, thermally stable, and suitable for diverse applications from space optics to solar energy harvesting.
The researchers synthesized an ultra-low reflective silica aerogel (URSA) using tetramethoxysilane as the precursor and dimethyl sulfoxide (DMSO) as the solvent. They chose DMSO due to its higher viscosity and density slowed sedimentation, and therefore can keep nanoparticles evenly dispersed during the rapid gelation process, which they controlled to occur within 30–60 seconds. Small-angle X-ray scattering and electron microscopy confirmed that the aerogel’s building blocks were just 7–8 nm across, a scale that minimized Rayleigh scattering and kept the refractive index close to air at around 1.03. This meant that, at the interface, Fresnel reflection dropped to nearly negligible levels. The authors incorporated over a hundred different kinds of nanoparticles, from semiconductors like MnO₂, MoS₂, and black phosphorus to conductors such as carbon nanotubes, MXenes, and metallic nanospheres into this transparent, low-scattering network. They found that for semiconductors, only those with band gaps below 1.59 eV could achieve full visible-light absorption when embedded in URSA. Testing Fe₂O₃ and TiO₂ confirmed the limitation—both showed diminished absorption beyond their theoretical cutoff wavelengths—while Fe₃O₄, with a band gap of 0.1 eV, maintained near-unity absorbance across the visible range. On the other hand, conductive fillers behaved differently, showing broadband absorption from ultraviolet into the infrared. The authors also reported that 2D Ti₃C₂ MXene reached 99.4% absorbance with only 0.005 vol% loading which is far lower than the threshold needed for 0D or 1D structures and this highlights how sheet-like geometries create more complete light barriers. The team pushed these composites into conditions that would destroy many known superblacks. Samples like URSA/MWCNT and URSA/Pt endured heating at 600 °C for six hours without losing their deep black appearance or optical performance, the aerogel’s mesopores preventing sintering of the metal nanoparticles. Mechanical tests were equally revealing—compression up to 10% strain did not disrupt the light-trapping structure, and stress limits reached 1 MPa in some formulations. They also explored functional add-ons: Fe₃O₄-filled aerogels produced magnetically manipulable superblacks that could hover when drawn by a magnet, while hydrophobically modified versions repelled water and cleaned themselves after immersion in muddy suspensions. Beyond durability, the porous architecture translated to tangible applications. When the team exposed it to solar illumination, hydrophilic variants drove rapid evaporation of water and ethanol, while hydrophobic ones floated to evaporate nonpolar liquids like hexane. Catalytic tests with Fe₃O₄-loaded aerogels accelerated dye degradation under sunlight, their black surfaces harvesting photons while the embedded catalyst sped the reaction. This suspending strategy effectively mitigates photon utilization inefficiencies and catalytic efficiency degradation induced by nanoparticle agglomeration. Indeed, across these experiments, a pattern emerged: the aerogel was not just a passive scaffold but an active enabler, making it possible for diverse absorbers to retain and even expand their capabilities in ways previously impractical.
In conclusion, the research work of Professor Zhang Xuetong and his group successfully developed a new universal and adaptable route to superblack fabrication. They achieved record‐level absorbance with individual nanoparticle systems, and demonstrated that the same aerogel‐based platform can accommodate a vast diversity of absorbers—metals, semiconductors, polymers, and hybrids—without requiring unique fabrication schemes for each. In doing so, it removes one of the most persistent bottlenecks in optical material design: the inability to generalize high‐performance architectures across fundamentally different materials. We believe the implications reach far beyond optical science and reducing the volume fraction of light‐absorbing nanoparticles required—down to as little as 0.005% for certain 2D systems—the new study points to lighter, more cost‐efficient designs that can be scaled without sacrificing performance. The combination of low density, high mechanical resilience, and thermal stability up to 600 °C opens the door for superblacks in aerospace, deep‐space exploration, and other environments where weight, durability, and optical suppression are equally critical. In astrophysical instrumentation, such materials could suppress stray light more effectively than existing coatings while withstanding the mechanical and thermal stresses of launch and orbit. Moreover, the multifunctionality of magnetic responsiveness, catalytic activity, hydrophobic self‐cleaning, and tailored evaporation behavior—suggests a new generation of “superblack plus” materials that merge optical control with additional, task‐specific capabilities. In renewable energy, they could serve as lightweight, floating solar evaporators for desalination or chemical processing in remote locations. In sensing and imaging, they might be engineered to combine light trapping with spectral selectivity or environmental resilience, producing instruments that function accurately in hostile or contaminated settings. It is worth mentioning another far‐reaching implication is the combinatorial potential. With over a hundred nanoparticle types already validated and countless possible mixtures, the platform can be tuned for specialized optical responses across ultraviolet, visible, and infrared ranges. This adaptability could help address niche industrial and scientific demands without the time‐intensive reinvention of the base structure and opens new opportunities for tailoring absorption spectra for camouflage across multiple detection bands, or for selective thermal management in solar harvesting systems.
About the author
Zhang Xuetong is currently a professor at Suzhou Institute of Nano-Tech and Nano-Bionics, Chinese Academy of Sciences (SlNANO). He obtained his Ph.D. degree (2002) from Beijing Institute of Technology, from 2002 to 2004, he did postdoctoral research at Peking University under the guidance of Prof. Liu Zhongyang and Prof. Zhang Jin. He worked as a research assistant at Brunel University from 2005 to 2007 and at University of York from2007 to 2008. After that, he joined Beijing Institute of Technology as a full professor and moved to SINANO in 2013. At present, he is also a visiting professor at University College London. His current scientific interests are focused on aerogel optical materials, aerogel fibers, aerogel-based solid-liquid composite materials, aerogel thermal insulation materials, and aerogel functional materials.
Reference
Li, Guangyong & Wang, Leyi & Ji, Xiaofei & Zhang, Xuetong. (2024). Suspending Light‐Absorbing Nanoparticles in Silica Aerogel Enables Numerous Superblacks. Advanced Materials. 37. 10.1002/adma.202412385.
downloadFile