Correlation between types of defects/vacancies of Bi2S3 nanostructures and their transient photocurrent |
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Authors: | Mingyang Liu Luqing Wang Pei Dong Liangliang Dong Xifan Wang Jarin Joyner Xiangjian Wan Boris I. Yakobson Robert Vajtai Pulickel Ajayan Pol Spanos |
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Affiliation: | 1. Department of Materials Science and Nanoengineering, Rice University, Houston, TX 77005, USA;2. Department of Chemistry, Rice University, Houston, TX 77005, USA;3. College of Chemistry, Nankai University, Tianjin 300071, China |
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Abstract: | Crystalline nanostructures possess defects/vacancies that affect their physical and chemical properties.In this regard,the electronic structure of materials can be effectively regulated through defect engineering;therefore,the correlation between defects/vacancies and the properties of a material has attracted extensive attention.Here,we report the synthesis of Bi2S3 microspheres by nanorod assemblies with exposed {211} facets,and the investigation of the types and concentrations of defects/vacancies by means of positron annihilation spectrometry.Our studies revealed that an increase in the calcined temperature,from 350 to 400 ℃,led the predominant defect/vacancy densities to change from isolated bismuth vacancies (VBi) to septuple Bi3+-sulfur vacancy associates (VBiBiBiSSSS).Furthermore,the concentration of septuple Bi3+-sulfur vacancy associates increased as the calcined temperature was increased from 400 to 450 ℃.The characterized transient photocurrent spectrum demonstrates that the photocurrent values closely correlate with the types and concentrations of the predominant defects/vacancies.Our theoretical computation,through first principles,showed that VBiBiBiSSSS strongly absorbs I2(sol),easily desorbs I-(sol),and enhances the electrocatalytic activity of the nanostructures. |
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Keywords: | Bi2S3 microspheres nanorod assembly defects/vacancies positron annihilation spectrometry transient photocurrent |
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