Study on the photocatalytic properties differences between the 1-D and 3-D W₁₈O₄₉ particles

The morphology of W₁₈O₄₉ catalysts has a significant effect on their photocatalytic performance. Herein, we successfully prepared two commonly used W₁₈O₄₉ photocatalysts just by changing the reaction temperature in the hydrothermal system, namely 1-D W₁₈O₄₉ nanowires (1-D W₁₈O₄₉) and 3-D urchin-like W₁₈O₄₉ particles (3-D W₁₈O₄₉), and evaluated the difference of their photocatalytic performances by taking the degradation of methylene blue (MB) as an example. Remarkably, 3-D W₁₈O₄₉ exhibited an impressive photocatalytic degradation performance towards MB with photocatalytic reaction rates of 0.00932 min^-1, which was about 3 times higher than that of 1-D W₁₈O₄₉. The comprehensive characterization and control experiments could further reveal that the hierarchical structure of 3-D W₁₈O₄₉ brought higher BET surface areas, stronger light harvesting, faster separation of photogenerated charges and so on, which was the main reason for its better photocatalytic performance. ESR results confirmed that the main active substances were superoxide radicals (˙O₂ ^-) and hydroxyl radicals (˙OH). This work aims to explore the intrinsic relationship between the morphology and photocatalytic properties of W₁₈O₄₉ catalysts, so as to provide a theoretical basis in the morphology selection of W₁₈O₄₉ or its composite materials in the field of photocatalysis.