Nanojunction-Mediated Photocatalytic Enhancement in Heterostructured CdS/ZnO, CdSe/ZnO, and CdTe/ZnO Nanocrystals

• Published in: Angewandte Chemie Vol. 126; no. 30; pp. 7972 - 7976
• Main Authors: Eley, Clive, Li, Tong, Liao, Fenglin, Fairclough, Simon Michael, Smith, Jason M., Smith, George, Tsang, Shik Chi Edman
• Format: Journal Article
• Language: English; German
• Published: Weinheim WILEY-VCH Verlag 21.07.2014; WILEY‐VCH Verlag; Wiley Subscription Services, Inc
• Subjects: Cadmium; Cadmium selenides; Cadmium tellurides; Chalcogenides; Chemistry; Halbleiter; Intermetallics; Nanocrystals; Nanokristalle; Nanostructure; Photocatalysis; Photokatalyse; Quantum dots; Rastersondentomographie; Semiconductors; Zinc oxide
• ISSN: 0044-8249; 1521-3757
• DOI: 10.1002/ange.201404481

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. Eine Serie von hoch aktiven Halbleiterphotokatalysatoren wurde durch Kristallisation von Wurtzit‐Tetraedern auf CdS‐, CdSe‐ und CdTe‐Quantenpunkten hergestellt. Die heterostrukturierten CdX/ZnO‐Nanokristalle weisen ausgedehnte Typ‐II‐Nanokontakte auf und bewirken die schnelle photokatalytische Zersetzung von organischen Molekülen in wässrigen Medien.