报告题目：Preparation of Near-IR-Responsive Multinary Quantum Dots and Their Photofunctions

报告时间：2020年11月10日（星期二）上午10:00-11:30

报告地点：腾讯会议

会议ID: 200 081 645

报 告 人：Prof. Tsukasa Torimoto（教授、名古屋大学）

报告摘要:

Semiconductor nanocrystals, so-called quantum dots (QDs), exhibit unique physicochemical properties depending on their particle size and shape. Especially, since I-III-VI-based QDs, such as AgInS₂ and CuInS₂, are composed of less toxic elements and have strong absorption coefficients in the visible wavelength region, these are attractive materials as Cd-free QDs for the application to solar energy conversion systems [1]. On the other hand, the near-IR responsivity seems necessary for QDs to efficiently utilize solar light. In general, the Eg of I-III-VI semiconductor decreases with use of Se as a group VI element in place of S. In this study, we report the solution-phase synthesis of AgInSe-based QDs and the investigation of their photocatalytic H₂ evolution activity.

We prepared spherical QDs composed of less-toxic ZnSe-AgInSe₂ solid solution ((AgIn)_xZn_2(1-x)Se₂, ZAISe(x)) via thermal decomposition of corresponding metal acetates and selenourea in oleylamine [2]. The chemical composition of ZAISe(x) QDs could be controlled by varying the fraction of Zn(OAc)₂ in metal precursors. Thus-obtained QDs had almost stoichiometric composition. The Eg of QDs was tunable from 1.47 to 2.96 eV in near-IR and visible wavelength regions by changing the x value from 1.0 to 0. The size of QDs slightly decreased from ca. 5 to 3 nm with a decrease in the x value. The photocatalytic activity of ZAISe(x) QDs was investigated for H₂ evolution as a model reaction. The irradiation to ZAISe(x) QDs suspended in an aqueous solution containing Na₂S and Na₂SO₃ as hole scavengers was carried out using Xe lamp light (λ> 350 nm). With the elapse of light irradiation, the amount of H₂ evolved increased, regardless of the kind of ZAISe(x) QDs. The H₂ evolution rate (R(H₂)) was remarkably dependent on the composition of ZAISe(x) QDs: A volcano-type dependence was observed between the R(H₂) and Eg of ZAISe(x) QDs (Fig. 1). The highest photocatalytic activity was obtained for ZAISe(0.5) QDs with Eg of 1.85 eV. This behavior can be explained by the changes in both the electronic energy structure of ZAISe QDs and the amount of photon absorption with the chemical composition.

[1] T. Torimoto, et al., J. Phys. Chem. Lett., 2014, 5, 336-347.

[2] T. Torimoto, et al., J, Mater. Chem. A, 2020, 8, 13142-13149.

报告人简介：

Tsukasa Torimoto教授自2005起就职于日本名古屋大学（Nagoya University）。

获奖情况：

2017 日本电化学协会科学成就奖

2016 日本光化学协会奖

2001日本电化学协会青年研究员奖