Ratio Of Metal Precursors Research Articles

Controlled Synthesis of Preferential Facet-Exposed Fe-MOFs for Ultrasensitive Detection of Peroxides.

Exposing different facets on metal-organic frameworks (MOFs) is highly desirable to enhance the performance for various applications, however, exploiting a concise and effective approach to achieve facet-controlled synthesis of MOFs remains challenging. Here, by modulating the ratio of metal precursors to ligands, the facet-engineered iron-based MOFs (Fe-MOFs) exhibits enhanced catalytic activity for Fenton reaction are explored, and the mechanism of facet-dependent performance is revealed in detail. Fully exposed (101) and (100) facets on spindle-shaped Fe-MOFs enable rapid oxidation of colorless o-phenylenediamine (OPD) to colored products, thereby establishing a dual-mode platform for the detection of hydrogen peroxide (H2O2) and triacetone triperoxide (TATP). Thus, a detection limit as low as 2.06nm is achieved, and robust selectivity against a wide range of common substances (>16 types) is obtained, which is further improved by incorporating a deep learning architecture with an SE-VGG16 network model, enabling precise differentiation of oxidizing agents from captured images. The present strategy is expected will shine light on both the rational synthesis of nanomaterials with modulated morphologies and the exploitation of high-performance trace chemical sensors.

Slow-release synthesis of Cu single-atom catalysts with the optimized geometric structure and density of state distribution for Fenton-like catalysis

Single-atom Fenton-like catalysis has attracted significant attention, yet the quest for controllable synthesis of single-atom catalysts (SACs) with modulation of electron configuration is driven by the current disadvantages of poor activity, low selectivity, narrow pH range, and ambiguous structure-performance relationship. Herein, we devised an innovative strategy, the slow-release synthesis, to fabricate superior Cu SACs by facilitating the dynamic equilibrium between metal precursor supply and anchoring site formation. In this strategy, the dynamics of anchoring site formation, metal precursor release, and their binding reaction kinetics were regulated. Bolstered by harmoniously aligned dynamics, the selective and specific monatomic binding reactions were ensured to refine controllable SACs synthesis with well-defined structure-reactivity relationship. A copious quantity of monatomic dispersed metal became deposited on the C3N4/montmorillonite (MMT) interface and surface with accessible exposure due to the convenient mass transfer within ordered MMT. The slow-release effect facilitated the generation of targeted high-quality sites by equilibrating the supply and demand of the metal precursor and anchoring site and improved the utilization ratio of metal precursors. An excellent Fenton-like reactivity for contaminant degradation was achieved by the Cu1/C3N4/MMT with diminished toxic Cu liberation. Also, the selective ·OH-mediated reaction mechanism was elucidated. Our findings provide a strategy for regulating the intractable anchoring events and optimizing the microenvironment of the monatomic metal center to synthesize superior SACs.

Highly Reproducible Epitaxial Growth of Wafer-Scale Single-Crystal Monolayer MoS2 on Sapphire.

2D semiconducting transition-metal dichalcogenides (TMDs) have attracted considerable attention as channel materials for next-generation transistors. To meet the industry needs, large-scale production of single-crystal monolayer TMDs in highly reproducible and energy-efficient manner is critically significant. Herein, it is reported that the high-reproducible, high-efficient epitaxial growth of wafer-scale monolayer MoS2 single crystals on the industry-compatible sapphire substrates, by virtue of a deliberately designed "face-to-face" metal-foil-based precursor supply route, carbon-cloth-filter based precursor concentration decay strategy, and the precise optimization of the chalcogenides and metal precursor ratio (i.e., S/Mo ratio). This unique growth design can concurrently guarantee the uniform release, short-distance transport, and moderate deposition of metal precursor on a wafer-scale substrate, affording high-efficient and high-reproducible growth of wafer-scale single crystals (over twoinches, six times faster than usual). Moreover, the S/Mo precursor ratio is found as a key factor for the epitaxial growth of MoS2 single crystals with rather high crystal quality, as convinced by the relatively high electronic performances of related devices. This work demonstrates a reliable route for the batch production of wafer-scale single-crystal 2D materials, thus propelling their practical applications in highly integrated high-performance nanoelectronics and optoelectronics.

Synthesis of bimetallic Ag-Au nanoparticles for surface-enhanced Raman scattering spectroscopy

In this report, bimetallic Au-Ag nanoparticles were successfully prepared by a chemical strategy using binary reduction agents. The metal ratio in bimetallic nanoparticles can be easily tuned by controlling the metal precursor ratio. Using Rhodamine as a probe molecule, we investigated the surface-enhanced Raman scattering (SERS) activity of synthesized bimetallic Au-Ag nanoparticles. The results demonstrate that our materials allow to enhance about 2×106 times the Raman signal of Rhodamine. Hence, the combination of unique features of two plasmonic metals opens up exciting prospects for the design of an ultra-sensitive sensor based on SERS.

Designing Structurally Ordered Pt/Sn Nanoparticles in Ionic Liquids and their Enhanced Catalytic Performance

AbstractMultimetallic nanoparticles (NPs) often exhibit enhanced catalytic properties that differ from their parent materials. Carefully exploring the structures of multimetallic NPs is a prerequisite for understanding the structure‐ and composition‐associated properties. Herein, intermetallic Pt/Sn NPs with tunable compositions are designed exploiting the beneficial properties of ionic liquids (ILs) in a one‐pot synthetic procedure. Metal salt precursors are reduced with triethylhydridoborate, whereby the cation of the triethylhydridoborate is adapted to the cation of the IL. Both the initial metal precursor ratio and the type of IL influence the structure of the NPs, with the effect of the IL being more pronounced. PtSn nanocrystals are obtained as phase pure products under optimized reaction conditions, whereby a microwave‐assisted approach leads to higher crystallinity. In the hydrogenation of α,β‐unsaturated aldehydes, the catalytic performance obviously depend on the NP composition. In bimetallic Pt/Sn NPs, higher Pt content leads to increased conversion, while increase in Sn increases selectivity to the cinnamic alcohol.

Synthesis and structure of Au19Ag4(S-Adm)15 nanocluster: Polymorphs and optical properties

Polymorphism is a common phenomenon in nature. Here, we report one-pot wet chemical method to synthesize two polymorphs of Au19Ag4(S-Adm)15 nanocluster protected by 1-adamantanethiol (HS-Adm), which adopt P-1 and P21/c space group respectively. The crystal structures of two polymorphs were determined by X-ray crystallography. Compared to the previously reported Au19Ag4(S-Adm)15 nanocluster adopting P21/n space group, polymorphs of Au19Ag4(S-Adm)15 with P-1 and P21/c space group show the different optical properties. Moreover, Au19Ag4(S-Adm)15 with P-1 space group exhibits good thermal stability. Meanwhile, we investigated the effect of solvent and molar ratio of metal precursors on the polymorphs. This work provides an insight to polymorphs of metal nanoclusters.

Facile Synthesis Of Composition-Controllable PtPdAuTe Nanowires As Superior Electrocatalysts For Direct Methanol Fuel Cells.

Multicomponent Pt-based nanowires (NWs) have attracted widespread attention as eletrocatalysts toward direct alcohol fuel cells because of their unique one-dimensional structure and high reaction dynamics. Quaternary PtPdAuTe NWs are designed via a facile template method, and NWs with a different composition are obtained by adjusting the feed ratio of metal precursors. The direct displacement reaction of metal precursors with Te NWs and the partial oxidation of Te lead to the formation of quaternary NWs. The rough surface and abundant reactive sites deriving from the rearrangement of metal atoms on the Te NWs surface endow the PtPdAuTe NWs with a superior electrocatalytic property and durability for methanol oxidation. The Pt20 Pd20 Au10 Te50 NWs display the largest mass activity and best stability among all catalysts. The preparation of PtPdAuTe NWs could provide a viable strategy for the preparation of other multicomponent NWs.

Zn-substituted iron oxide nanoparticles from thermal decomposition and their thermally treated derivatives for magnetic solid-phase extraction

Controlled thermal decomposition of zinc and iron acetylacetonates in the presence of oleic acid and oleylamine provided surfactant-capped magnetic nanoparticles with narrow size distribution and the mean diameter of ≈15 nm. The combined study by XRD, XRF and Mössbauer spectroscopy revealed three important features of the as-prepared nanoparticles. First, the actual ratio of Zn:Fe was considerably lower in the product compared to the initial ratio of metal precursors (0.14 vs. 0.50). Second, a pure stoichiometric Zn-doped magnetite system, specifically of the composition Zn0.37Fe2.63O4, with no signatures of oxidation to maghemite was formed. Third, Zn2+ ions were distributed at both tetrahedral and octahedral sites, and the observed preference for the tetrahedral site was only twice as high as for theoctahedral site. Furthermore, carbon-coated nanoparticles were achieved by pyrolysis of the surfactants at 500 °C, providing a potential sorbent of organic pollutants with room-temperature magnetization as high as 79.1 emu g−1 and very low carbon content of 5 wt%. The thermal treatment, albeit intended only for the carbonization of surfactants, did alter also the non-equilibrium cation distribution toward the equilibrium one by the relocation of a considerable fraction of the octahedrally coordinated Zn2+ to the tetrahedral sites. Preliminary experiments with magnetic solid-phase extraction of β-estradiol from aqueous solutions evidenced applicability and reusability of the carbon-coated product in the separation of steroid pollutants.

Colloidal CuZnInS3 nanocrystals as the sensitizer in photovoltaic solar cells

This research article is presenting photovoltaic performance of a sensitized solar cell with CuZnInS3 as the sensitizer. The as-prepared nanocrystals were tested for the Cu:Zn composition dependent performance of photovoltaic solar cells. Out of all the tested nanocrystals with various compositions, a power conversion efficiency as high as 1.1% was observed with Cu:Zn 1:2 composition. A simple, low temperature method was employed to synthesize highly luminescent CuZnInS3 quaternary nanocrystals using chloride salts of metal precursors. The synthesis was done by heating metal precursors followed by injection of elemental sulfur. The size and the elemental composition of the nanocrystals were investigated using transmission electron microscopy (TEM) and X-ray energy dispersive spectroscopy (EDS) The nanocrystals showed a uniform size distribution with average particle size of 5 nm with the exception of Cu:Zn 1:1 sample. The findings showed that the optical properties of these nanocrystals can be tuned by varying Cu:Zn metal precursor ratio. The as-synthesized nanocrystals showed photoluminescence quantum yield as high as 68%.

Preparation and Characterization of Bimetallic Fe-Ni Oxide Nanoparticles Using Liquid Phase Plasma Process.

The Fe-Ni oxide bimetallic nanoparticles (FNOBNPs) were synthesized in the liquid phase plasma (LPP) method employed an iron chloride and nickel chloride as metal precursors. The sphericalshaped FNOBNPs were synthesized by the LPP process and, the size of particles was growing along with the progression of LPP reaction. The synthesized FNOBNPs were comprised of Fe₃O₄ and NiO. Iron had a higher reduction potential than nickel and resulted in higher iron composition in the synthesized FNOBNPs. The control of molar ratio of metal precursors in initial reactant solution was found that it could be employed as a means to control the composition of the elements in FNOBNP.

A facile synthesis of Ag@PdAg core-shell architecture for efficient purification of ethene feedstock

Precise control of elemental configurations within multimetallic nanoparticles could enable access to functional nanomaterials with significant performance benefits. Here, we present a one-pot synthesis of supported Ag@PdAg core-shell catalyst with an ordered PdAg alloy shell and an Ag core. Both the relative reduction potential and ratio of metal precursors are essential for this synthesis strategy. The distinguished properties of Ag@PdAg, particularly the electronic structure, indicates the existence of electron modification not only between Pd and Ag on PdAg shell, but between Ag core and alloy shell. The Ag@PdAg catalyst displays 97% ethene yield in the partial hydrogenation of acetylene, which is 2.0 and 8.1 times that of over PdAg alloy and pure Pd catalysts, and this is the most selective catalyst reported to data under industrial evaluation conditions. Moreover, this core-shell structure exhibits preferable stability with comparison to PdAg alloy catalyst. The facile synthesis of core-shell architecture with alloy shell structure provides a new platform for efficient catalytic transfer of chemical resource.

Improving Electrocatalysts for Oxygen Evolution Using NixFe3–xO4/Ni Hybrid Nanostructures Formed by Solvothermal Synthesis

Spinel-type oxides have been found to be active electrocatalysts for OER. However, their semiconductor character severely limits their catalytic performance. Herein, we report a facile solvothermal pathway for the synthesis of spinel-type NixFe3–xO4 oxides/Ni metal nanocomposites. The good electrical contact between the metal and semiconductor oxide interface and well-tuned compositions of NixFe3–xO4 spinel oxides are crucial to achieve better OER performance. Specifically, the NixFe3–xO4/Ni nanocomposite sample prepared from a metal precursor ratio of y = 0.15 [y = Fe/(Fe + Ni)] that results in an x value of about 0.36 exhibits catalytic activity with an overpotential of 225 mV to achieve an electrocatalytic current density of j = 10 mA cm–2 and a Tafel slope of 44 mV dec–1 in alkaline electrolyte. This study not only provides new perspectives to designing nanocomposite catalysts for OER but also opens a promising avenue for further enhancing electrocatalytic performance via interface and composition eng...

Synthesis of Samarium-Cobalt Sub-micron Fibers and Their Excellent Hard Magnetic Properties.

High-throughput synthesis of Samarium-Cobalt sub-micron fibers with controlled composition and dimension was demonstrated by combining electrospinning and reduction-diffusion processes. The composition of fibers was readily varied (8 < Sm < 20 at.%) by adjusting precursor composition whereas the diameter of fibers was precisely controlled by varying electrospinning parameters (e.g., applied voltage, solution feed rate, temperature, and humidity) to reach single-domain size. X-ray diffraction patterns confirmed that single phase Sm2Co17 fibers were synthesized when the metal precursor ratio (Sm3+/(Sm3++Co2+)) was precisely controlled at 10.6%, whereas mixed phases (i.e., Co-Sm2Co17 or Sm2Co17-Sm2Co7) were observed when the ratio is deviated from the stoichiometric. Magnetic saturation (Ms) of the synthesized fibers monotonically decreased with an increased in Sm content. In contrast, coercivity (Hci) monotonically increased with an increase in Sm content.

A Rational Solid-State Synthesis of Supported Au-Ni Bimetallic Nanoparticles with Enhanced Activity for Gas-Phase Selective Oxidation of Alcohols.

A facile confined solid-state seed-mediated alloying strategy is applied for the rational synthesis of supported Au-Ni bimetallic nanoparticles (BMNPs). The method sequentially deposits nickel salts and AuNP seeds into the ordered array of extra-large mesopores (EP-FDU-12 support) followed by a high-temperature annealing process. The size, structure, and composition of the AuNi BMNPs can be well tuned by varying the AuNP seeds, annealing temperature, and feeding ratio of metal precursors. Kinetic studies and DFT calculations suggest that the introduction of the Ni component can significantly prompt the O2 activation on AuNPs, which is critical for the selective alcohol oxidation using molecular O2 as the oxidant. The optimal Au-Ni BMNP catalyst showed the highest turnover frequency (TOF) (59 000 h-1, 240 °C) and highest space-time yield (STY) of benzyl aldehyde (BAD) productivity (9.23 kg·gAu-1·h-1) in the gas-phase oxidation of benzyl alcohol (BA), which is at least about 5-fold higher than that of other supported Au catalysts.

PtNi Nanocrystals Supported on Hollow Carbon Spheres: Enhancing the Electrocatalytic Performance through High-Temperature Annealing and Electrochemical CO Stripping Treatments.

PtNi nanoparticles have been proved to be a type of highly efficient electrocatalyst for the oxygen reduction reaction (ORR) among the Pt-based nanomaterials. However, how to improve the surface catalytic activity and stability of polymer-stabilized Pt-based nanocrystals is still a critical issue for their application in fuel cells. In this work, a one-step solvothermal process was used to synthesize PVP-stabilized PtNi nanocubes supported on hollow carbon spheres. With optimized metal precursor ratio (Pt/Ni = 1:1) and solvothermal temperature (130 °C), PtNi nanocrystals with uniform size and cubic shape can be synthesized and highly dispersed on hollow carbon spheres. To improve the electrocatalytic activity of the PtNi nanocrystals, the synthesized composite was treated by a heating annealing at 300 °C and a subsequent electrochemical CO stripping process. It was found that the two-step treatment can significantly enhance the catalytic activity of the PtNi nanocrystals for ORR with high durability. In addition, the prepared PtNi composite also showed higher catalytic activity and stability for methanol oxidation. The obtained peak current density on the present catalyst can reach 3.89 A/mgPt, which is 9 times as high as commercial Pt/C (0.43 A/mgPt). The present study not only demonstrates a general method to synthesize hollow carbon sphere-supported nanoparticle catalysts but also provides an efficient strategy to active the surface activity of nanoparticles.

Carbon nanofiber-supported PdNi alloy nanoparticles as highly efficient bifunctional catalysts for hydrogen and oxygen evolution reactions

Efficient bifunctional electrocatalysts for the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) must be developed to realize an inexpensive water-splitting system for large-scale applications. Herein, a novel PdNi carbon nanofiber (PdNi/CNF) catalyst was synthesized by facile electrospinning and carbonization processes. The size and homogeneity of the Pd−Ni alloy nanoparticles (NPs) could be effectively tuned by controlling the molar feed ratio of metal precursors .The morphology and structure of the PdNi/CNFs were characterized, and the working electrodes fabricated from the prepared catalyst mats were directly employed in the HER and OER. The PdNi/CNFs-1:2 catalyst exhibits high catalytic activity in the HER with a low overpotential of 55mV at a current density of 10mAcm−2 in an acidic solution. Moreover, under 1M KOH electrolyte, an overpotential of 187mV is required in the HER over the catalyst to arrive 10mAcm−2 and an overpotential of 289mV is achieved in the OER at the same current density. The superior HER and OER activities of the PdNi/CNFs are attributed to the synergistic effects of the PdNi alloy nanoparticles (NPs) assembled on the CNFs. This work provides a simple route for synthesizing highly efficient bifunctional electrocatalysts from 3d transition metals and a small amount of noble metals for hydrogen and oxygen evolution reactions.

(Invited) Enhancement of Photocatalytic H2 Evolution Activity of ZnS-AgInS2 Solid Solution Nanocrystals By Controlling Their Shape Anisotropy

Photocatalytic activities of semiconductor particles are well known to be varied depending on the particle morphology as well as their chemical composition. As for semiconductor nanocrystals, most studies have been carried out with binary semiconductors to determine the correlations of crystal size and shape with their physicochemical properties. For example, the photocatalytic H2 evolution rate became larger for multi-armed CdS rod nanocrystals than spherical or non-branched rod crystals.[1] On the other hand, much interest has recently been shown in I-III-VI-based multinary metal chalcogenide semiconductor crystals as light-absorbing materials for solar cells and photocatalyts because of their tunable physicochemical properties with chemical composition and their low toxicity compared to that of conventional Cd-based binary semiconductors. So far we carried out photocatalytic H2 evolution with spherical ZnS-AgInS2 solid solution ((AgIn)xZn2(1-x)S2, ZAIS) nanocrystals as a photocatalyst, the activity being controlled by their size and chemical composition. In this study, we report shape-controlled synthesis of ZAIS nanocrystals via two-step heat treatment process and investigate their photocatalytic H2evolution activity as a function of chemical composition.[2] ZAIS nanocrystals with anisotropic shapes were prepared by thermal decomposition of corresponding metal acetates and sulfur compounds of elemental sulfur and 1,3-dibutylthiourea in oleylamine at 250 oC. Since thus-obtained crude particles contained both rod- and rice-shaped nanocrystals, the size-selective precipitation was adopted to isolate ZAIS nanocrystals with individual anisotropic shapes. The chemical composition of rod-shaped ZAIS nanocrystals was controlled by changing metal precursor ratio in preparation, while post-preparative Zn2+-doping was carried out to increase the Zn2+ content in rice-shaped nanocrystals. For comparison, spherical ZAIS nanocrystals (diameter: ca. 5.5 nm) were prepared by the same method reported previously.[3] Thus-obtained ZAIS nanocrystals were suspended in a 2-propanol/water mixture solution containing Na2S as a hole scavenger and then irradiated with Xe lamp light (λ> 350 nm) to investigate their photocatalytic H2evolution activity. The heat treatment at 250 oC produced rod-shaped ZAIS nanocrystals with length of ca. 30 nm and width of ca. 5 nm. The chemical composition was controlled from x=0.35 to 0.11, in which the absorption onset was blue-shifted from ca. 470 nm to 370 nm. Rice-shaped ZAIS nanocrystals (size: ca. 9 × ca.16 nm), isolated by size-selective precipitation, had almost constant x value of ca. 0.8~0.9 regardless of the precursor metal ratio in preparation, and then post-preparative Zn2+ doping was necessary to vary the chemical composition from 0.92 to 0.25, in which the absorption onset was also blue-shifted from 650 nm to 490 nm with a decrease in x value. TEM measurement revealed that each ZAIS nanocrystal was composed of a single crystal with hexagonal crystal structure, regardless of particle shape. The photocatalytic H2 evolution rate, R(H2), was significantly varied depending on the Eg of ZAIS nanocrystals if the comparison was made for the particles with a constant morphology, as shown in Fig. 1, in which the photocatalytic activity became optimal at x of 0.35~0.45 regardless of nanocrystal shapes. In contrast, R(H2) increased with nanocrystal shape in the order of rice < sphere < rod. The highest apparent quantum yield for photocatalytic H2evolution was 5.9% for rod-shaped ZAIS nanocrystals, being about two-times larger than that obtained with spherical nanocrystals. Reference [1] Liu, et al., Dalton T 2014, 43, 7245-7253. [2] Torimoto, et al., ACS Appl. Mater. Interfaces 2016, 8, 27151-27161. [3] Torimoto, et al., J. Phys. Chem. C 2015, 119, 24740-24749. Figure 1 (a) TEM images of ZAIS nanocrystals with rod, sphere, and rice shapes. (b) Relationship between R(H2) and Eg of ZAIS nanocrystals. The numbers in panel b represent the x values. Figure 1

Preparation of Au/Pd Bimetallic Nanoparticles by a Microwave-Induced Plasma in Liquid Process

Abstract Au/Pd alloy nanoparticles (NPs) were successfully synthesized using HAuCl4, H2PdCl4, and α-thioglycerol as precursors and a stabilizer, respectively, by microwave-induced plasma in liquid process (MWPLP). After only several minutes of microwave irradiation, metallic NPs were obtained in aqueous environment without any reducing agent. The reduction mechanism of metal ions was confirmed by UV–vis spectral changes. The results from HAADF-STEM and EDS indicated that synthesized NPs were bimetallic Au/Pd. Moreover, XRD patterns of synthesized NPs implied that the composition of bimetallic NPs could be controlled by changing the initial ratio of metal precursors.

Controlling Shape Anisotropy of ZnS-AgInS2 Solid Solution Nanoparticles for Improving Photocatalytic Activity.

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-AgInS2 solid 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 H2 evolution 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 H2 evolution was 5.9% for rod-shaped ZAIS particles, being about two times larger than that obtained with spherical particles.

(Invited) Shape-Dependent Photocatalytic H2 Evolution Activity of ZnS-AgInS2 Solid Solution Nanoparticles

Nanoscale materials exhibit size- and shape-dependent physicochemical properties due to both the quantum size effect and the difference in the crystal facets exposed to the solution. So far the preparation for Cd-based II-VI nanoparticles with anisotropic shapes has been intensively investigated via solution phase synthetic methods. Especially rod-shaped nanoparticles have attracted much attention because of unique optical and electronic properties originating from their one-dimensional particle shape, such as polarized emission, improved solar cell performance, and higher photocatalytic activity. On the other hand, recent research efforts have been focused on developing high-quality semiconductor nanoparticles containing no toxic elements such as Cd or Pb. Nanoparticles composed of I, III, and VI group elements, such as AgInS2, CuInS2, and Cu(In,Ga)Se2, have been a promising alternative to Cd-based particles, because their light absorption properties and electronic energy structure could be controlled by modifying the size and shape of nanoparticles as well as by making solid solutions with II-VI group semiconductors. We have reported(1) that nanoparticles of low-toxic ZnS-AgInS2 solid solution ((AgIn)xZn2(1-x)S2, ZAIS), prepared by thermal decomposition of corresponding metal acetates and thiourea in a hot organic solution, exhibited tunable optical properties depending on their chemical composition and particles size. Furthermore these spherical ZAIS nanoparticles worked as an efficient photocatalyst for H2evolution. However little is known about the dependence of photocatalytic activity on the particle shape. In this study, we prepare ZAIS particles with different anisotropic shapes to enhance their photocatalytic activity. ZAIS nanoparticles with anisotropic shapes were prepared by thermal decomposition of corresponding metal acetates and sulfur compounds of elemental sulfur and 1,3-dibutylthiourea in oleylamine at 250 oC. The obtained crude particle mixture was subjected to size-selective precipitation to isolate ZAIS particles with individual anisotropic shapes. The chemical composition of thus-obtained particles was controlled by changing metal precursor ratio. For comparison, spherical ZAIS particles were prepared as reported previously.(1) The photocatalytic activity of ZAIS nanoparticles was investigated for H2 evolution from aqueous solution as a model reaction. ZAIS particles suspended in a 2-propanol/water mixture solution containing Na2S as a hole scavenger was irradiated with Xe lamp light (λ> 350 nm). The heat treatment at 250 oC for 3 min produced rod-like particles with length of ca. 40 nm and width of ca. 5 nm. With further heating for 10 min, rice-shaped particles were formed as a by-product, the dimensions of which were length of ca.18 nm and width of ca. 9 nm. Rice-shaped particles could be isolated from rod particles by size-selective precipitation. Figure 1a shows TEM images of purified ZAIS particles with rod and rice shapes, as well as spherical particles for comparison. XRD patterns of individual kinds of particles well agreed with wurtzite crystal structure of ZAIS solid solution. The chemical composition of obtained ZAIS particles were almost stoichiometric and the fraction of Zn2+in total metal ions was tunable depending on the ratio of metal precursors in preparation. The irradiation of ZAIS particles suspended in 2-propanol/water solution containing S2- as a sacrificial electron donor induced H2 evolution. Figure 1b shows the time courses of the amount of H2 evolved by irradiation to ZAIS particles with various shapes, in which the x value, representing the solid solution composition of particles, was similar to 0.35-0.45. Regardless of particle shapes, the amount of H2 evolution was linearly increased with elapse of irradiation, indicating that each kind of ZAIS particles efficiently worked as a photocatalyst. However the photocatalytic activity was greatly dependent on the shape of particles, though the Eg of particles was similar to ca.2.3-2.5 eV. ZAIS particles with rod-like and spherical shapes exhibited much higher H2evolution rate than rice-like particles. The highest activity was obtained for rod-like particles, which was ca. 1.5 times larger than that of spherical ones. Since rod-like ZAIS exhibited longer PL lifetime than spherical particles, we concluded that the enhanced photocatalytic activity of rod-like ZAIS particles originated from the change in lifetime of photogenerated charge carriers with the particle size and/or shape. Reference (1) T. Torimoto, et al., J. Phys. Chem. C 119, 24740-24749 (2015). Figure 1