title: Controlling Shape Anisotropy of ZnS-AgInS2Solid Solution Nanoparticles for Improving Photocatalytic Activity.
abstract: Independently controlling the shape anisotropy and chemical composition of multinary semiconductor particles is important for preparing highly efficient photocatalysts. In this study, we prepared ZnS-AgInS2solid solution ((AgIn)xZn2(1-x)S2, ZAIS) nanoparticles with well-controlled anisotropic shapes, rod and rice shapes, by reacting corresponding metal acetates with a mixture of sulfur compounds with different reactivities, elemental sulfur, and 1,3-dibutylthiourea, via a two-step heating-up process. The chemical composition predominantly determined the energy gap of ZAIS particles: the fraction of Zn2+in rod-shaped particles was tuned by the ratio of metal precursors used in the nanocrystal formation, while postpreparative Zn2+doping was necessary to increase the Zn2+fraction in the rice-shaped particles. The photocatalytic H2evolution rate with irradiation to ZAIS particles dispersed in an aqueous solution was significantly dependent on the chemical composition in the case of using photocatalyst particles with a constant morphology. In contrast, photocatalytic activity at the optimum ZAIS composition, x of 0.35-0.45, increased with particle morphology in the order of rice (size: ca. 9 × ca. 16 nm) < sphere (diameter: ca. 5.5 nm) < rod (size: 4.6 × 27 nm). The highest apparent quantum yield for photocatalytic H2evolution was 5.9% for rod-shaped ZAIS particles, being about two times larger than that obtained with spherical particles.
authors.affiliation: Graduate School of Engineering, Nagoya University , Nagoya 464-8603, Japan.
authors.forename: Tsukasa
authors.initials: T
authors.lastname: Torimoto
authors.affiliation: Graduate School of Engineering, Nagoya University , Nagoya 464-8603, Japan.
authors.forename: Yutaro
authors.initials: Y
authors.lastname: Kamiya
authors.affiliation: Graduate School of Engineering, Nagoya University , Nagoya 464-8603, Japan.
authors.forename: Tatsuya
authors.initials: T
authors.lastname: Kameyama
authors.affiliation: Institute of Industrial Science, The University of Tokyo , Tokyo 153-8505, Japan.
authors.forename: Hiroyasu
authors.initials: H
authors.lastname: Nishi
authors.affiliation: Graduate School of Engineering, Osaka University , Suita, Osaka 565-0871, Japan.
authors.forename: Taro
authors.initials: T
authors.lastname: Uematsu
authors.affiliation: Graduate School of Engineering, Osaka University , Suita, Osaka 565-0871, Japan.
authors.forename: Susumu
authors.initials: S
authors.lastname: Kuwabata
authors.affiliation: Center for Advanced Research of Energy Conversion Materials, Hokkaido University , Sapporo 060-8628, Japan.
authors.forename: Tamaki
authors.initials: T
authors.lastname: Shibayama
keywords: anisotropic crystal growth; multinary metal sulfide; photocatalyst; quantum dot; semiconductor nanoparticle; solid solution