Controlling the Electronic Energy Structure of ZnS鈥揂gInS2 Solid Solution Nanocrystals for Photoluminescence and Photocatalytic Hydrogen Evolution

详细信息    查看全文

• 作者：Tatsuya Kameyama ; Takuya Takahashi ; Takahiro Machida ; Yutaro Kamiya ; Takahisa Yamamoto ; Susumu Kuwabata ; Tsukasa Torimoto
• 刊名：Journal of Physical Chemistry C
• 出版年：2015
• 出版时间：November 5, 2015
• 年：2015
• 卷：119
• 期：44
• 页码：24740-24749
• 全文大小：664K
• ISSN：1932-7455

文摘

Simultaneous control of the size and chemical composition is an advantageous strategy to obtain the desired photochemical properties of multinary semiconductor nanocrystals, ZnS-AgInS₂ solid solution ((AgIn)_xZn_2(1鈥?i>x)S₂, ZAIS) nanocrystals (NCs), being different from conventional binary nanocrystals. The energy gap (E_g) of ZAIS NCs was enlarged with a decrease in particle size due to the quantum size effect or with an increase in ZnS content in the ZAIS solid solution. The levels of the conduction band edge and valence band edge, determined by photoelectron spectroscopy in air, were shifted more negatively and more positively, respectively, with an increase in E_g. A volcano-type dependence was observed between the PL quantum yield (QY) and the size of ZAIS NCs, in which the optimal PL QY for each x value was obtained at a similar particle size around 5鈥? nm, except for x = 1.0, and maximum QY was recorded to be 79% for ZAIS NCs prepared with x = 0.5. The photocatalytic activity for H₂ evolution was also greatly dependent on both the size and the chemical composition of ZAIS NCs, and then the highest activity was observed for ZAIS NCs having an average diameter of about 4.2鈥?.5 nm and E_g of 2.3鈥?.4 eV. This can be reasonably explained by the enlargement of the driving force to reduce protons in the solution with a negative shift of the conduction band edge of ZAIS NCs and by the quenching of photoexcited ZAIS NCs with an increase in the amount of surface defect sites and/or with the formation of deeper trap sites along with a decrease in the particle size.