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A novel solar selective absorbing MoSi2-Al2O3 multilayer coating deposited on Cu or stainless steel (SS) substrate by magnetron sputtering is reported. The coating consists of an infrared reflective metal layer using Mo or Cu, an absorption MoSi2-Al2O3 bilayer, and an anti-reflection Al2O3 layer from substrate to top. With the help of computer simulation, we obtain the optimal metal volume fraction and thickness of each layer on Cu substrate. And then a good optical performance (α/ε) of 0.94/0.06 for the all-layer coating on Cu substrate is obtained. On the other hand, the influence of the deposition parameters for the infrared reflective Mo layer on the emittance is discussed. The emittance decreases with the decrease of sputtering pressure and the increase of the target power. The lowest emittance of the SS (substrate)/Mo is 0.047 after optimization. The optical performance (α/ε) of the all-layer coating on the optimized SS/Mo substrate is 0.95/0.07. The thermal stability of the all-layer coating on SS substrate is evaluated, and it is found to have a good thermal stability at 400 °C, due to the choice of MoSi2, which means a good candidate of solar selective absorbing coating for parabolic trough concentrated solar power (CSP). [ABSTRACT FROM AUTHOR]

Highlights: [•] We first proposed to use a AlNi alloy to fabricated cermet absorption coating. [•] We obtained an excellent optical property AlNi–Al2O3 absorbing coating. [•] Preliminary thermal stability tests show AlNi–Al2O3 coating is promising for CSP. [ABSTRACT FROM AUTHOR]

Semiconducting ternary metal oxide thin films exhibit a promising application for solar energy conversion. However, the efficiency of the conversion is still limited by a band gap of a semiconductor, which determines an obtainable internal photovoltage for solar water splitting. In this report the tunability of the tin tungstate band gap by O 2 partial pressure control in the magnetron co-sputtering process is shown. A deficiency in the Sn concentration increases the optical band gap of tin tungstate thin films. The optimum band gap of 1.7 eV for tin tungstate films is achieved for a Sn to W ratio at unity, which establishes the highest photoelectrochemical activity. In particular, a maximum photocurrent density of 0.375 mA cm−2 at 1.23 V RHE and the lowest reported onset potential of −0.24 V RHE for SnWO 4 thin films without any co-catalyst are achieved. Finally, we demonstrate that a Ni protection layer on the SnWO 4 thin film enhances the photoelectrochemical stability, which is of paramount importance for application. Image 1 • Variation of oxygen partial pressure changes Sn to W ratio which tunes the band gap. • Optimum band gap (1.7 eV) results in the highest photocurrent density (0.375 mA cm−2). • The lowest onset potential of - 0.24 V RHE is achieved for tin tungstate film. • Photoelectrochemical stability of the films is improved by NiO x protection layer. • Initial open circuit potential of 0.107 V is measured upon AM 1.5 illumination. [ABSTRACT FROM AUTHOR]

In this work, the NbTiSiN and NbTiSiON layers are used instead of NbTiN and NbTiON layers to further improve the thermal stability of Al/NbTiN/NbTiON/SiO 2 multilayer solar selective absorbing coating. The thermal stability of Si-doped individual layers and multilayer coatings are investigated. The X-ray diffraction (XRD) results show that Si incorporation into NbTiN (NbTiSiN) layer does not change its preferred orientation, and the Si-doped NbTiON (NbTiSiON) layer remains in amorphous phase. On the other hand, by introducing Si into NbTiN and NbTiON layers induce significant improvement of the oxidation resistance at 500 °C in air. After ageing in air at 500 °C for 2 h, the absorptance and emittance (at 400 °C) of Al/NbTiN/NbTiON/SiO 2 and Al/NbTiSiN/NbTiSiON/SiO 2 multilayer coatings change from 0.934/0.13 and 0.931/0.12 to 0.538/0.14 and 0.922/0.13, respectively. Meanwhile the surface roughness increases from 18.3 and 7.9 to 41.5 and 14.7 respectively, as atomic force microscopy (AFM) shows. The Al/NbTiSiN/NbTiSiON/SiO 2 coating still has a high absorptance (0.910) and low emittance (0.13, at 400 °C) after ageing at 550 °C in vacuum for 100 h. It displays that Si-doping play an important role in the improvement of the thermal stability. [ABSTRACT FROM AUTHOR]