Bioinspired self-standing macroporous Au/ZnO sponges for enhanced photocatalysis.

A self-standing macroporous noble metal-zinc oxide (ZnO) sponge of robust 3D network has been fabricated through in-situ growth method. The key to the construction of the bioinspired sponge lies in the choice of commercial polyurethane sponge (CPS) with interconnected and junction-free macroporous structure as the skeleton to support Au/ZnO nanorods (Au/ZnONRs). The resultant Au/ZnO/CPS not only exhibits hierarchical structures representing physical features of CPS, but also demonstrates durable superior photocatalytic activity and hydrogen generation capability. In addition, we have adopted various irradiations to investigate the effect of UV light and visible light on the photocatalytic performance of Au/ZnO/CPS individually. In detail, the photocatalytic properties of Au/ZnO/CPS and ZnO/CPS have been monitored and compared under irradiations of different wavelengths (200-1100, 350-780, 200-420 and 420-780 nm) for 90 min to reveal the effect of irradiation wavelength on the activity of photocatalysts. A possible mechanism between irradiation wavelength and photocatalytic degradation efficiency is proposed. The facile in-situ growth approach presented herein can be easily scaled up, affording a convenient method for the preparation of self-standing 3D macroporous materials, which holds great potential for the application in both environmental purification and solar-to-hydrogen energy conversion.