Low-temperature hydrothermal fabrication of Fe3O4 nanostructured solar selective absorption films

Textured surface with complex nanostructure is considered as an important route for high efficient solar collector. Herein, we report a low-temperature one-step hydrothermal method to prepare Fe3O4 textured films for solar selective absorber. Surface morphology and thickness of Fe3O4 films can be tuned by the factors of alkaline concentration and reaction time. The irradiated photons can be effectively trapped in the interior space of the porous nanostructure by multi-reflection within the inner surface of irregular pores constructed by Fe3O4 nanoparticles. The as-prepared Fe3O4 films display excellent absorptivity (0.74-0.93) and low emittance (0.11-0.62). The absorption in the short wavelength zone (0.3-2.5 mu m) mainly depends on the surface morphology, and the emission in the long wavelength zone (2.5-20 mu m) is mainly determined by the thickness of the foamed nanostructure. This work develops a novel, low-cost, energy saving and environmentally friendly method to fabricate solar selective absorption films, which shows a good prospect in large area synthesis for solar energy utilization.