Xinyang Jiao

Novel Fabrication and Enhanced Photocatalytic MB Degradation of Hierarchical Porous Monoliths of MoO 3 Nanoplates

Porous monoliths of MoO3 nanoplates were synthesized from ammonium molybdate (AHM) by freeze-casting and subsequent thermal treatment from 300 to 600 °C. Pure orthorhombic MoO3 phase was obtained at thermal treatment temperature of 400 °C and above. MoO3 monoliths thermally treated at 400 °C displayed bimodal pore structure, including large pore channels replicating the ice crystals and small pores from MoO3 sheets stacking. Transmission electron microscopy (TEM) images revealed that the average thicknesses of MoO3 sheet were 50 and 300 nm in porous monoliths thermally treated at 400 °C. The photocatalytic performance of MoO3 was evaluated through degradation of methylene blue (MB) under visible light radiation and MoO3 synthesized at 400 °C exhibited strong adsorption performance and best photocatalytic activity for photodegradation of MB of 99.7% under visible illumination for 60 min. MoO3 photocatalyst displayed promising cyclic performance, and the decolorization efficiency of MB solution was 98.1% after four cycles.

Effect of heating rate on porous TiAl-based intermetallics synthesized by thermal explosion

ABSTRACT TiAl-based porous materials were synthesized by a novel process of thermal explosion (TE) reaction. The effects of heating rate on the expansion behavior of powder assemblies, phase compositions, and pore structures were investigated. Results showed that the actual temperature of specimen increased rapidly from 655 to 661°C (furnace temperature) to 1018–1136°C (combustion temperature) in a short time interval of 25–55 s, indicating that an obvious TE reaction occurred at different heating rates (1, 2, 5, and 10°C min−1). TE reaction in Ti/Al powder assemblies resulted in the formation of open-celled TiAl-based intermetallics. When the heating rate was set at 5°C min−1, the maximum open porosity of 59% was obtained in Ti-Al bodies, which experienced the highest combustion temperature (1136°C) and underwent maximum volume expansion (48%). The pore size distribution was uniform and pores were interconnected in TE products.