Electrochemical synthesis of inorganic polycrystalline electrodes with controlled architectures
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Introduction Polycrystalline electrodes are broadly used in many electrochemical and photoelectrochemical devices because of their low production cost and facile processability compared to single-crystalline electrodes. However, the interfacial structures of polycrystalline electrodes are often ill defined, making it difficult to understand their effects on the electrode properties. In order to improve the electrode performance based on a firm understanding of interfaceproperty relationships, it is critical to have a synthesis method that can produce various electrodes composed of the same material with diverse and systematically varying interfacial structures. Electrochemical synthesis is an effective method to achieve this goal due to several intrinsic advantages. First, the solution-based nature of electrochemical synthesis allows for the manipulation of many synthesis variables (e.g., pH, additives, types of solvents, temperature) that markedly affect the shapes and rates of inorganic growth. Second, in electrochemical synthesis, deposition potential and current serve as additional and powerful synthesis variables that provide an exceptional level of control over electrode morphologies. The deposition potential and current can be set as
constants or varied over time and applied for any time interval, thus providing a vast array of growth conditions. In addition, the change in potential and current can be monitored during the synthesis and used to provide invaluable insight and fine control over the growth process. Third, materials naturally grow directly from a conducting substrate (i.e., a working electrode) during electrochemical synthesis and, therefore, the nucleation density of materials, which affects crystal size and grain boundary areas, also becomes a controllable factor. Fourth, electrodeposition allows for the creation of multicomponent, multijunction electrodes having uniform and conformal junctions even when a substrate with a complex interfacial structure is used as the working electrode. Since many devices require multicomponent and multijunction electrodes/catalysts, the quality and design of the interfacial structures of these electrodes play a critical role in determining their overall efficiencies. Fifth, the material types that can be produced by electrochemical synthesis are broad and include metals, oxides, hydroxides, II–VI, and III–V materials. Therefore, a strategy developed to direct a certain morphology can be applied to various materials.
Kyoung-Shin Choi, Purdue University, West Lafayette, IN 47907, USA, [email protected] Ho Seong Jang, Purdue University, West Lafayette, IN 47907, USA, [email protected] Colleen M. McShane, Purdue University, West Lafayette, IN 47907, USA, [email protected] Carrie G. Read, Purdue University, West Lafayette, IN 47907, USA, [email protected] Jason A. Seabold, Purdue University, West Lafayette, IN 47907, USA, [email protected]
MRS BULLETIN • VOLUME 35 • OCTOBER 2010 • www.mrs.org/bulletin
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ELECTROCHEMICAL SYNTHESIS OF INORGANIC POLYCRYSTALLINE EL
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