Refractory Ultrathin Nanocomposite Solar Absorber with Superior Spectral Selectivity and Thermal Stability

Abstract

Highly efficient solar–thermal energy conversion requires refractory absorbers harnessing full spectrum of sunlight, minimal thermal emission, and structural stability at higher operating temperatures. Herein, an ultrathin ultrabroadband omnidirectional silicon carbide–tungsten (SiC‐W) refractory nanocomposite is fabricated by high‐throughput co‐sputtering with superior thermal and oxidation stability. The as‐fabricated SiC‐W nanocomposite (78 nm) deposited on tungsten layer with top anti‐reflective film exhibits high solar absorptance of 95.45% in the wide range of 250–2500 nm with thermal emittance below 0.05 at ambient temperature. The ultrabroadband absorption is achieved by plasmonic resonances triggered by self‐formed tungsten nanoclusters in the range of 500–1500 nm combined with SiC intrinsic absorption below λ < 500 nm. SiC as diffusion barrier also prevents interlayer diffusion and oxidation of tungsten nanoclusters to achieve superior thermal/oxidation stability, when annealed at 900 K (air) and 1050 K (vacuum). This work demonstrates outstanding capability of refractory nanocomposites in high‐performance solar thermal technologies for both terrestrial and space environments.

Tungsten Based Spectrally Selective Absorbers with Anisotropic Rough Surface Texture

“…The Gaussian surface described using the Gaussian PSD function is one of the simple approximations of random surface roughness. The three-dimensional Gaussian randomness being achieved from specifying a given spectral density referring to [ 53 ]: where h is the root mean square (RMS), and are the correlation length along the x- and y-directions, respectively, and is the wavevector in the radial direction. Moreover, and .…”

Spectrally Selective Absorbers/Emitters for Solar Steam Generation and Radiative Cooling‐Enabled Atmospheric Water Harvesting

“…W is the most frequently used metal in cermets because of its high optical loss and high‐temperature reliability. [ 128–135 ] In 2015, Cao et al. demonstrated a multilayer cermet of W and Ni nanoparticles and a Al 2 O 3 host by a co‐sputtering method, showing a high of 90% and a low of 15% at 500 °C, as well as thermal stability at 600 °C (Figure 11b).…”

“…developed a W–SiC based cermet absorber to simultaneously offer a high of 95% and a low of 5% at 100 °C, which was thermally stable at 777 °C in a vacuum (Figure 11d,e). [ 131 ] In addition to W, other refractory and lossy metals including Mo, Ta, Cr, Ni, and TiN were also exploited to construct cermets. [ 136–138 ] The main concern of cermet SSAs is their instability at extremely high temperatures mainly caused by two factors.…”

“…Reproduced with permission. [ 131 ] Copyright 2020, Wiley‐VCH. f) Reflectance spectra of SSAs based on W–SiO 2 cermets and W multilayers.…”

Enhanced Liquid Propagation and Wicking Along Nanostructured Porous Surfaces

“…A good wick surface can be made by introducing micro-/nanostructures to an intrinsically hydrophilic surface. [19][20][21] For widely used materials (i.e., metal, ceramic, and carbon based), different approaches have been addressed to create micro-/nanostructures, including chemical etching, [22] electrochemical deposition, [23] physical vapor deposition, [24] annealing, [25] anodization, [26] and so on. [27,28] Meanwhile, micro-/ nanostructured surfaces can enable a large area of thin-film evaporation for liquids with low thermal resistance and high heat transfer rate, making them attractive for high heat flux cooling applications.…”