Since black silicon was discovered by coincidence, the special material was explored for many amazing material characteristics in optical, surface topography, and so on. Because of the material property, black silicon is applied in many spheres of a photodetector, photovoltaic cell, photo-electrocatalysis, antibacterial surfaces, and sensors. With the development of fabrication technology, black silicon has expanded in more and more applications and has become a research hotspot. Herein, this review systematically summarizes the fabricating method of black silicon, including nanosecond or femtosecond laser irradiation, metal-assisted chemical etching (MACE), reactive ion etching (RIE), wet chemical etching, electrochemical method, and plasma immersion ion implantation (PIII) methods. In addition, this review focuses on the progress in multiple black silicon applications in the past 10 years. Finally, the prospect of black silicon fabricating and various applications are outlined.

No abstract

The core-shell structured Co3O4-PANI nanocomposites have been successfully prepared using an in situ polymerization method, while the core Co3O4 nanoparticles were synthesized by carbon-assisted method using degreasing cotton as a template. The obtained samples were characterized by XRD, TEM, FTIR, and XPS. The results indicated that the amorphous PANI was well covered on the surface of the spinel Co3O4 and the Co3O4-PANI with core-shell structure was formed with particle size of about 100 nm. The interfacial interaction of the core-shell nanocomposite greatly enhances the microwave absorption properties. The maximum reflection loss of Co3O4-PANI is up to −45.8 dB at 11.7 GHz with a thickness of 2.5 mm and the adsorption bandwidth with the reflection loss below −10 dB reaches 14.1 GHz ranging from 3.9 to 18 GHz when the thickness is between 2 and 5.5 mm. Therefore, the facilely synthesized and low-cost Co3O4-PANI nanocomposite with superior microwave absorption properties can be a promising nanomaterial for high efficient microwave absorption.

No abstract

in size and geometry, and they are categorized as micro/nanoscale [10-14] and order/ disordered forms. [15,16] Noteworthy, the structures with high aspect ratio [7,17-19] and with size matching the wavelength of incident light [6,9,20] exhibit low reflectivity. [9,21] The former parameter extends the optical path of incident light, [10,22] while the latter dimension facilitates coupling between light and materials. [5,23] These effects allow the incident light to get trapped and decayed in the surface structures, giving rise to ultralow reflection at near-ultraviolet (UV) to visible (vis) wavelengths. [24-26] A series of fabrication approaches, including metal-assisted chemical etching, [27,28] electrochemical etching, [29,30] and reactive ion etching (RIE) [9] has been developed to create such surface textures. In particular, RIE enables highly selective etching and produces smooth, vertical profiles, as well as higher structural resolution and density. [31,32] Research into such processes has focused on mask-assisted [33-37] and maskless etching, [38-41] both of which can be effectively used to produce black silicon with micro/nanoscale features. Although a few studies have proposed the combination of micro-and nanostructures, they mainly focused on the suppression of light reflection at the wavelengths below 1100 nm. The antireflectance of black silicon in the near-infrared (NIR) range (over 1100 nm) is still weak due to silicon's intrinsic bandgap of 1.12 eV. [5] Antireflectivity is one of the critical factors defining the performance of black silicon in optical, photothermal, photochemical, and optoelectronic applications. The photonic applications under visible light illumination are commonly tuned through surface texturing; however, their promising performance under longer wavelength (>1100 nm) requires either intrinsic lattice modifications or additional substance enhancement. Recent advances in microfabrication and material engineering have enabled in-depth exploration into the synergy between surface texturing and material reinforcement. In this study, black silicon with novel chimney-like hierarchical micro/nanostructures is fabricated via two-step reactive ion etching, and subsequently gold nanoparticles (Au NPs) are loaded on the black silicon by magnetron sputtering deposition. The micro/nanostructures result in synergy effect with the Au NPs on suppression of light reflection. An ultralow broadband reflection (<1%, wavelength 220-2600 nm) is achieved from the Au-loaded black silicon substrates. The impact of Au NPs and structural design such as size, spacing, shape, and etching duration on antireflectivity of black silicon is investigated. This study opens up new avenue for high-efficiency applications of black silicon in the fields of sustainable energy and photonics/microelectronics.