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Metastable Tetragonal Cu 2 Se Hyperbranched Structures: Large‐Scale Preparation and Tunable Electrical and Optical Response Regulated by Phase Conversion
Author(s) -
Zhu Jinbao,
Li Qiuyang,
Bai Liangfei,
Sun Yongfu,
Zhou Min,
Xie Yi
Publication year - 2012
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.201200899
Subject(s) - tetragonal crystal system , metastability , materials science , nanoparticle , phase (matter) , copper , nanoscopic scale , nanotechnology , chemical engineering , chemistry , metallurgy , organic chemistry , engineering
Despite the promising applications of copper selenide nanoparticles, an in‐depth elucidation of the inherent properties of tetragonal Cu 2 Se (β‐Cu 2 Se) has not been performed because of the lack of a facile synthesis on the nanoscale and an energy‐intensive strategy is usually employed. In this work, a facile wet‐chemical strategy, employing HCOOH as reducing agent, has been developed to access single‐crystalline metastable β‐Cu 2 Se hyperbranched architectures for the first time. The process avoids hazardous chemistry and high temperatures, and thus opens up a facile approach to the large‐scale low‐cost preparation of metastable β‐Cu 2 Se hyperbranched architectures. A possible growth mechanism to explain the formation of the β‐Cu 2 Se dendritic morphology has been proposed based on time‐dependent shape evolution. Further investigations revealed that the metastable β‐Cu 2 Se can convert into the thermodynamically more stable cubic α‐Cu 2− x Se maintaining the dendritic morphology. An increase in electrical conductivity and a tunable optical response were observed under ambient conditions. This behavior can be explained by the oxidation of the surface of the β‐Cu 2 Se hyperbranched structures, ultimately leading to solid‐state phase conversion from β‐Cu 2 Se into superionic conductor α‐Cu 1.8 Se, which has potential applications in energy‐related devices and sensors.