Vaporthermal-driven rapid transformation of commercial gibbsite to rhombic boehmite flakes

The large-scale and controllable production of boehmite has attached much attention due to its extensive application in advanced energy and electronics industries. In this study, a facile vaporthermal (VPH) method was developed for the rapid fabrication of rhombic boehmite microflakes using low-cost commercial gibbsite particles. The evolution behaviors of gibbsite to boehmite under VPH and conventional hydrothermal (LPH) conditions were ex-situ monitored by XRD , Raman, and FT-IR techniques. The boehmite powders from VPH (V-boehmite) and LPH (L-boehmite) have similar crystal structure and bonding vibration information, whereas V-boehmite exhibits rhombic morphology and L-boehmite presents cubic morphology. Moreover, the formation time of boehmite can be shortened from 16 h of LPH to 6 h of VPH at 180 °C, which significantly contributes to its scalable production. These differences of V-boehmite are attributed to the direct contact between high-temperature saturated water steam and gibbsite, which can induce the rapid formation of rhombic boehmite microflakes through dissolution-recrystallization mechanism. Therefore, the vaporthermal technology has great potential for efficient, sustainable, and large-scale production of boehmite powders.