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Thin film compound semiconductor solar cells, including copper indium sulfide (CIS), have potential as next-generation power supply sources. However, recent fabrication processes include gas phase reactions, which consume much energy and generate abundant loss of material resources. Therefore, the development of alternative eco-friendly methods without a gas phase reaction has been actively researched. Herein, we synthesize CIS nanoparticles via a liquid phase reaction using iminodiacetic acid (IDA) and glycine (Gly) as the complex reagent to homogenize copper and indium complexes. The X-ray diffraction (XRD) profiles of the as-synthesized nanoparticles in a buffer solution exhibit broad peaks, which nearly correspond to CIS. These peaks grow sharply after annealing. Selected area electron diffraction and high-resolution transmission electron microscopies indicate the presence of the (112) phase of CIS but the crystallinity of our CIS with IDA and Gly differs. The results indicate that maintaining a homogenized condition of metal complexes by pH stabilization using a buffer solution might be maybe important for aqueous synthesis of CIS.

Films made of closely packed Cu nanoparticles (NPs) were obtained by drop casting Cu NP inks. The capillary immersion force exerted during the drying of the inks caused the Cu NPs to attract each other, resulting in closely packed Cu NP films. The apparent density of the films was found to depend on the type of solvent in the ink because the capillary immersion force is affected by the solvent surface tension and dispersibility of Cu NPs in the solvent. The closely packed particulate structure facilitated the sintering of Cu NPs even at low temperature, leading to low-resistivity Cu films. The sintering was also enhanced with a decrease in the size of NPs used. We demonstrated that a closely packed particulate structure using Cu NPs with a mean diameter 61.7 nm showed lower resistivity (7.6 μΩ cm) than a traditionally made Cu NP film (162 μΩ cm) after heat treatment.

Bi2Te3 nanoparticles (NPs) were synthesized with controlled mean diameters of 58 nm, 82 nm, and 100 nm using an aqueous chemical reduction, in which ascorbic acid was used instead of the commonly employed toxic reducing agent. In general, organic capping agents remained on the Bi2Te3 NP surfaces, which prevented the sintering of Bi2Te3 NPs and affected their thermoelectric properties. Not only the capping agent, but also water from the synthesis process, remained on the Bi2Te3 NPs even after their consolidation by spark plasma sintering. Consequently, evaporation of the water led to the collapse of sintered Bi2Te3 NPs when heated above 100°C. After the complete removal of the surface impurities and water, the sintered Bi2Te3 NPs became stable. To achieve enhanced thermoelectric properties, a high relative density of ∼ 96% was achieved in the sintered Bi2Te3 NPs without large grain growth by optimizing the sintering temperature and holding time. Subsequently, their thermoelectric properties showed that zT of the sintered Bi2Te3 NPs 100 nm in size is higher (0.41 at 390 K) than those of smaller sizes (58 nm and 82 nm). Finally, the effect of grain size, particle size and density on their thermoelectric properties is discussed.

A reasonable structure is crucial for the solar‐to‐chemical conversion process of the integrated Z‐scheme system. Composition modulation provides a new dimension for the optimization of Z‐scheme system. Herein, a composition modulated NiWO4/Pt/CdS Z‐scheme system is demonstrated for photocatalytic hydrogen generation. Proportions of Ni, W, Cd, and S in NiWO4/Pt/CdS are precisely tuned through the ion‐exchange reaction between NiWO4 and CdS. Important features of the Z‐scheme system in terms of light harvesting, charge separation and charge transfer are optimized accordingly. Bandgap of CdS is tuned continuously from 2.22 to 1.52 eV through controlling the Cd and S contents in NiWO4/Pt/CdS. The results of photoluminescence spectrometry and photoelectrochemical analyses demonstrate that the NiS generated from ion‐exchange reaction increase the charge separation and transfer rates. Furthermore, the molar ratio of NiWO4 to CdS is regulated to a balance state, leading to the decrease of charge recombination. The optimized NiWO4/Pt/CdS Z‐scheme system delivers the comprehensive performance of excellent light harvesting and charge separation abilities, low charge recombination rate, and suitable energy band structure for water reduction. The hydrogen generation rate is increased to 14.39 mmol h‐1g‐1 after the optimization. The optimized method brings a new insight into the rational design of Z‐scheme system. Composition of NiWO4/Pt/CdS was constructed and modulated by the ion‐exchange reaction between NiWO4 and CdS. Bandgap of CdS in NiWO4/Pt/CdS was tuned continuously by the composition modulation. The photoluminescence spectrometry and photoelectrochemical analyses demonstrate that the charge recombination of NiWO4/Pt/CdS was reduced by the composition modulation. The light harvesting, charge separation and transfer properties of NiWO4/Pt/CdS were optimized.

A modified alcohol reduction process by controlling the complexation and reduction of metallic ions was developed to obtain compositionally and structurally controlled Ni–Pt nanoparticles (NPs) with sizes less than 20 nm in a high yield. The characterization of NPs synthesized under different experimental conditions suggested that the reduction of Pt and subsequent formation of cubic-shaped Ni–Pt NPs were strongly dependent on the formation of Pt-oleylamine (OAm) complexes. Thus, prior to the synthesis of Ni–Pt NPs, the formation and reduction process of Pt complexes in the solution-state were investigated by in situ UV–Visible and X-ray spectroscopies. The complexation of Pt ions along with their reduction prior to the formation of Pt metal and their influence on the size and the elemental distribution of Pt within the Ni–Pt NPs were revealed. Then, the above findings were actively utilized to design and to obtain Pt(core)–Ni(shell), Ni–Pt alloy, and Ni(core)–Pt(shell) nanostructures by regulating the OAm concentration in the system. The specific distribution of Pt on the Ni–Pt surface was confirmed by decolorization of methylene blue. Furthermore, Ni–Pt NPs with a Pt concentration of 10 at.% exhibited a mass activity four times larger than that of commercial Pt during the oxygen reduction reaction (ORR).

To apply CuInSe2 (CIS)-based printable solar batteries; an aqueous phase synthesis method of Cu-In (CI) alloy nanoparticles is studied. Metal complexes in the original solution are restricted to homogenized species by utilizing calculations. For example; [(Cu2+)(ASP2−)2] [ASP: the “body (C4H5O4N)” of aspartic acid (C4H7O4N)] is predominant in the pH 6–13 region (CASP/CCu > 6); while In complexes can be restricted to [(In3+)(OH−)(EDTA4−)] (pH 10–12; CEDTA/CIn = 2) and/or [(In3+)(ASP2−)2] (pH 7–9; CASP/CIn = 5). These results indicate that the added amount of complex reagents should be determined by calculations and not the stoichiometric ratio. The reduction potential of homogenized metal complex is measured by cyclic voltammetry (CV) measurements and evaluated by Nernst’s equation using the overall stability constants. CuIn alloy nanoparticles with a small amount of byproduct (In nanoparticles) are successfully synthesized. The CI precursor films are spin-coated onto the substrate using a 2-propanol dispersion. Then the films are converted into CIS solar cells; which show a maximum conversion efficiency of 2.30%. The relationship between the open circuit potential; short circuit current density; and fill factor indicate that smoothing of the CIS films and improving the crystallinity and thickness increase the solar cell conversion efficiency.

A reasonable structure is crucial for the solar‐to‐chemical conversion process of the integrated Z‐scheme system. Composition modulation provides a new dimension for the optimization of Z‐scheme system. Herein, a composition modulated NiWO 4 /Pt/CdS Z‐scheme system is demonstrated for photocatalytic hydrogen generation. Proportions of Ni, W, Cd, and S in NiWO 4 /Pt/CdS are precisely tuned through the ion‐exchange reaction between NiWO 4 and CdS. Important features of the Z‐scheme system in terms of light harvesting, charge separation and charge transfer are optimized accordingly. Bandgap of CdS is tuned continuously from 2.22 to 1.52 eV through controlling the Cd and S contents in NiWO 4 /Pt/CdS. The results of photoluminescence spectrometry and photoelectrochemical analyses demonstrate that the NiS generated from ion‐exchange reaction increase the charge separation and transfer rates. Furthermore, the molar ratio of NiWO 4 to CdS is regulated to a balance state, leading to the decrease of charge recombination. The optimized NiWO 4 /Pt/CdS Z‐scheme system delivers the comprehensive performance of excellent light harvesting and charge separation abilities, low charge recombination rate, and suitable energy band structure for water reduction. The hydrogen generation rate is increased to 14.39 mmol h ‐1 g ‐1 after the optimization. The optimized method brings a new insight into the rational design of Z‐scheme system.

In the early stage of transcription, eukaryotic RNA polymerase II (Pol II) exchanges initiation factors with elongation factors to form an elongation complex for processive transcription. Here we report the structure of the Pol II elongation complex bound with the basal elongation factors Spt4/5, Elf1, and TFIIS. Spt4/5 (the Spt4/Spt5 complex) and Elf1 modify a wide area of the Pol II surface. Elf1 bridges the Pol II central cleft, completing a “DNA entry tunnel” for downstream DNA. Spt4 and the Spt5 NGN and KOW1 domains encircle the upstream DNA, constituting a “DNA exit tunnel.” The Spt5 KOW4 and KOW5 domains augment the “RNA exit tunnel,” directing the exiting nascent RNA. Thus, the elongation complex establishes a completely different transcription and regulation platform from that of the initiation complexes.

The deep trefoil knot architecture is unique to the SpoU and tRNA methyltransferase D (TrmD) (SPOUT) family of methyltransferases (MTases) in all three domains of life. In bacteria, TrmD catalyzes theN¹-methylguanosine (m¹G) modification at position 37 in transfer RNAs (tRNAs) with the36GG37sequence, using S-adenosyl-L-methionine (AdoMet) as the methyl donor. The m¹G37-modified tRNA functions properly to prevent +1 frameshift errors on the ribosome. Here we report the crystal structure of the TrmD homodimer in complex with a substrate tRNA and an AdoMet analog. Our structural analysis revealed the mechanism by which TrmD binds the substrate tRNA in an AdoMet-dependent manner. The trefoil-knot center, which is structurally conserved among SPOUT MTases, accommodates the adenosine moiety of AdoMet by loosening/retightening of the knot. The TrmD-specific regions surrounding the trefoil knot recognize the methionine moiety of AdoMet, and thereby establish the entire TrmD structure for global interactions with tRNA and sequential and specific accommodations of G37 and G36, resulting in the synthesis of m¹G37-tRNA.