Synthesis of monolithic zirconia aerogel via a nitric acid assisted epoxide addition method

Monolithic zirconia aerogels were prepared using zirconium oxychloride (ZrOCl2) as the precursor in the presence of the epoxide (PO) in both ethanol and mixed ethanol–water solutions, respectively. The effects of nitric acid and water contents on the gel formation behavior and the properties of the resulting aerogel were investigated. The results show that at a molar ratio of HNO3/ZrOCl2 of 1.0 and H2O/ZrOCl2 of 10, the translucent monolithic ZrO2 aerogels were obtained and they exhibited a well-developed mesoporous structure and a high specific surface area of 454 m2 g−1. The as-prepared aerogels were composed of mainly amorphous phase and a spot of ZrO2 crystal. After calcination at 750 °C for 2 h, the ZrO2 transformed into tetragonal phase. These results suggested that this HNO3-assisted epoxide addition method was a simple and controllable way to get translucent monolithic zirconia aerogels.