Enhancing solar-thermal energy conversion with silicon-cored tungsten nanowire selective metamaterial absorbers

Abstract

Summary This work experimentally studies a silicon-cored tungsten nanowire selective metamaterial absorber to enhance solar-thermal energy harvesting. After conformally coating a thin tungsten layer about 40 nm thick, the metamaterial absorber exhibits almost the same total solar absorptance of 0.85 as the bare silicon nanowire stamp but with greatly reduced total emittance down to 0.18 for suppressing the infrared emission heat loss. The silicon-cored tungsten nanowire absorber achieves an experimental solar-thermal efficiency of 41% at 203°C during the laboratory-scale test with a stagnation temperature of 273°C under 6.3 suns. Without parasitic radiative losses from side and bottom surfaces, it is projected to reach 74% efficiency at the same temperature of 203°C with a stagnation temperature of 430°C for practical application, greatly outperforming the silicon nanowire and black absorbers. The results would facilitate the development of metamaterial selective absorbers at low cost for highly efficient solar-thermal energy systems.

Defect States-Related Photothermal Conversion of UV Photons in TiO2-Based Materials

“…Next, the photothermal conversion experiments of samples were conducted under controlled conditions (see details in the Supporting Information: Method One). There are reports in the literature about the surface texture-enhanced absorption , /spectral selectivity. , The powders were ball milled with solvents to form a slurry and then sprayed onto the copper substrate with high thermal conductivity to prepare coatings (Figure S5) for further photothermal testing. The Cu substrate renders a uniform temperature distribution (Figure S6) under irradiation.…”

Metamaterials for Energy Harvesting

“…The silicon-cored WNW (Tungsten nanowire) shown in Fig. 12 was fabricated by depositing thin layers of tungsten at 1A 0 /S deposition rate on 2D Si -NW ( nanowire) [17]. The thermal performance of the fabricated metamaterial was evaluated at concentrated solar irradiation up to 20 suns (1 sun = 1.5 kW/m 2 ) using a developed solar test kit of a 1kW solar simulator, 1 ft 3 volume vacuum chamber, optical filters, and mirrors.…”

The chiral coating on an achiral nanostructure by the secondary effect in focused ion beam induced deposition

“…The superconductivity of tungsten directly deposited by FIB has been deeply investigated [46,47]. At room temperature, although its conductivity is slightly weaker than traditional optical materials such as Au and Ag, free electrons can also cause enough LSPRs [48,49], to enhance the optical activity. Besides, the sharp drop of resistivity at low temperature provides the tungsten material fabricated by FIBID with the possibility of a phase change material candidate [15,26].…”