| 초록 |
Visible-light-driven photocatalysis, which is cost-effective and highly efficient under solar irradiation, is considered to core technology for practical application of photocatalysis in industry. Among various developed photocatalysts, Ti3+ self-doped titanium dioxide (black TiO2) has recently emerged as one of the most promising visible-light-driven photocatalysts due to its superior absorption capacity and facility for charge separation. Currently developed synthetic techniques are focused on the reduction step of as-prepared white TiO2. However, the large-size powder such as microspheres with morphological advantages in photocatalysis are relatively difficult to synthesize by the reduction-based methods due to its low surface energy. Moreover, these methods are not compatible with cost-effective mass production because it is required a long and complex process to synthesize the black TiO2. An incomplete oxidation approach during the decomposition and crystallization of titanium precursors in anoxic atmospheres is a facile and competitive because it simultaneously induces the formation of defects and crystallization into TiO2. This approach can synthesize a relatively large size powder and reduce the processing time. In spite of these advantages, previously reported studies to attempt this concept carried out step-by-step processes that are divided into precursor preparation and incomplete oxidation. These processes are also complex and require a long time being similar to the reduction-based process, so the benefit of incomplete oxidation concept is faded. Therefore, it is necessary to develop a facile and novel method for synthesizing incompletely oxidative black TiO2. In this study, black TiO2 microspheres are successfully synthesized by a one-step synthesis process based on an ultrasonic spray pyrolysis method. This synthetic process is simple, fast, cost-effective, and scalable due to the direct introduction of oxygen defects during the synthetic process. This work demonstrates that ultrasonic spray pyrolysis is facile and versatile for synthesizing visible-light-driven black metal oxide microsphere photocatalysts. |
