RESUMO
A series of highly efficient semiconductor nanocrystal (NC) photocatalysts have been synthesized by growing wurtzite-ZnO tetrahedrons around pre-formed CdS, CdSe, and CdTe quantum dots (QDs). The resulting contact between two small but high-quality crystals creates novel CdX/ZnO heterostructured semiconductor nanocrystals (HSNCs) with extensive type-II nanojunctions that exhibit more efficient photocatalytic decomposition of aqueous organic molecules under UV irradiation. Catalytic testing and characterization indicate that catalytic activity increases as a result of a combination of both the intrinsic chemistry of the chalcogenide anions and the heterojunction structure. Atomic probe tomography (APT) is employed for the first time to probe the spatial characteristics of the nanojunction between cadmium chalcogenide and ZnO crystalline phases, which reveals various degrees of ion exchange between the two crystals to relax large lattice mismatches. In the most extreme case, total encapsulation of CdTe by ZnO as a result of interfacial alloying is observed, with the expected advantage of facilitating hole transport for enhanced exciton separation during catalysis.
RESUMO
Nb(2)O(5) nanorods and nanospheres were synthesized, and their photocatalytic activity for methylene blue decomposition in water compared. Nb(2)O(5) nanorods clearly displayed higher activity, despite their comparable surface area. With a shape-dependent surface acidity, hydrothermal stability, and high photoactivity, these Nb(2)O(5) nanorods are a unique and exciting nanomaterial for non-classical photocatalytic mineralization of organic compounds in water.
