Facile Synthesis Bi2Te3 Based Nanocomposites: Strategies for Enhancing Charge Carrier Separation to Improve Photocatalytic Activity

Varying structure Bi2Te3-based nanocomposite powders including pure Bi2Te3, Bi2Te3/Bi core−shell, and Bi2Te3/AgBiTe2 heterostructure were synthesized by hydrothermal synthesis using Bi2S3 as the template and hydrazine as the reductant. Successful realization of Bi2Te3-based nanostructures were concluded from XRD, FESEM, and TEM. In this work, the improvement in the performance of the rhodamine B (RhB) decomposition efficiency under visible light was discussed. The Bi2Te3/AgBiTe2 heterostructures revealed propitious photocatalytic performance ca. 90% after 60 min. The performance was over Bi2Te3/Bi core-shell nanostructures (ca. 40%) and more, exceeding pure Bi2Te3 (ca. 5%). The reason could be scrutinized in terms of the heterojunction structure, improving the interfacial contact between Bi2Te3 and AgBiTe2 and enabling retardation in the recombination rate of the photogenerated charge carriers. A credible mechanism of the charge transfer process in the Bi2Te3/AgBiTe2 heterostructures for the decomposition of an aqueous solution of RhB was also explicated. In addition, this work also investigated the stability and recyclability of a Bi2Te3/AgBiTe2 heterojunction nanostructure photocatalyst. In addition, this paper anticipates that the results possess broad potential in the photocatalysis field for the design of a visible light functional and reusable heterojunction nanostructure photocatalyst.

n-n Type Heterojunction Enabling Highly Efficient Carrier Separation in Inorganic Solar Cells

Carrier separation in a solar cell usually relies on the p-n junction. Here we show that n-n type inorganic semiconductor heterojunction is also able to separate the exciton for efficient solar cell applications. The n-n type heterojunction was formed by hydrothermal deposition of Sb2(S,Se)3 and thermal evaporation of Sb2Se3. We found that the n-n junction is able to enhance the carrier separation by the formation of an electric field, reduce the interfacial recombination and generate optimized band alignment. The device based on this n-n junction shows 2.89% net efficiency improvement to 7.75% when compared with the device consisted of semiconductor absorber-metal contact. The study in the n-n type solar cell is expected to bring about more versatile materials utility, new interfacial engineering strategy and fundamental findings in the photovoltaic energy conversion process.