Shape Control of Monodispersed Sub-5 nm Pd Tetrahedrons and Laciniate Pd Nanourchins by Maneuvering the Dispersed State of Additives for Boosting ORR Performance.

It is a great challenge to simultaneously control the size, morphology, and facets of monodispersed Pd nanocrystals under a sub-5 nm regime. Meanwhile, quantitative understanding of the thermodynamic and kinetic parameters to maneuver the shape evolution of nanocrystals in a one-pot system still deserves investigation. Herein, a systematic study of the density functional theory (DFT)-calculated adsorption energy, thermodynamic factors, and reduction kinetics on Pd growth patterns is reported by combining theory and experiments, with a focus on the dispersed state of additives. As pure models, monodispersed Pd tetrahedrons enclosed by (111) facets with a narrow size distribution of 4.9 ± 1 nm and a high purity approaching 98% can be obtained when using 1,1'-binaphthalene (C20 H14 ) +2NH3 as additives. Specifically, laciniate Pd nanourchins (Pd LUs) can evolve via anisotropic growth when replacing additive with dose-consistent 1,1'-binaphthyl-2,2'-diamine (C20 H16 N2 , two NH2 binding in C20 H14 ). Catalytic investigations show that the sub-5 nm Pd tetrahedrons exhibit higher activity in both the oxygen reduction (Eonset = 1.025 V, E1/2 = 0.864 V) and formic acid oxidation reaction with respect to the Pd LUs and Pd black, which represents a great step for the development of well-defined Pd nanocrystals with size in the sub-5 nm regime as non-Pt electrocatalysts.

Facile synthesis of PdFe alloy tetrahedrons for boosting electrocatalytic properties towards formic acid oxidation.

The controllable synthesis of multi-metal nanocrystals with a tetrahedral shape is significant for constructing high-efficiency electrocatalysts. However, due to the great distinction among the thermodynamic reduction potentials of different metal precursors, it is difficult to achieve tetrahedron-shaped alloy nanocrystals with a uniform {111} crystal surface and low surface energy. Herein, we reported a one-pot hydrothermal synthetic strategy to achieve high-yield PdFe alloy tetrahedrons. The unique structure endowed an impressive surface area-to-volume ratio, well distribution of Pd and Fe sites, and essential electronic effects, due to which they could be employed as formic acid oxidation reaction (FAOR) catalysts. As expected, the PdFe alloy tetrahedrons exhibited 4.8 and 2.4 times higher mass activity (595.8 A g-1) and specific activity (33.4 A m-2) compared to commercial Pd black, respectively; they also showed enhanced electrocatalytic stability and good resistance to CO poisoning. This work demonstrates the potential applications of bimetal Pd-based tetrahedrons as promising anode catalysts in a direct formic acid fuel cell.

Improved Efficiency of Perovskite Solar Cells by the Interfacial Modification of the Active Layer.

As the most promising material for thin-film solar cells nowadays, perovskite shine for its unique optical and electronic properties. Perovskite-based solar cells have already been demonstrated with high efficiencies. However, it is still very challenging to optimize the morphology of perovskite film. In this paper we proposed a smooth and continuous perovskite active layer by treating the poly (3, 4-ethylenedioxythiophene): poly (styrenesulphonate) (PEDOT:PSS) with pre-perovskite deposition and dimethylsulfoxide (DMSO) rinse. The scanning electron microscope (SEM) and atomic force microscope (AFM) images confirmed a perovskite active layer consisting of large crystal grains with less grain boundary area and enhanced crystallinity. The perovskite devices fabricated by this method feature a high power conversion efficiency (PCE) of 11.36% and a short-circuit current (Jsc) of 21.9 mAcm-2.

[Determination of bismuth pectin by flow-injection hydride-generation atomic absorption spectrometry].

A new method was developed by flow-injection hydride-generation atomic absorption spectrometry (FI-HG-AAS) for direct determination of bismuth in bismuth pectin, which is mostly composed of pectin and bismuth and serves as one of pharmaceuticals for protecting stomach mucous membrane. The influences of some experimental parameters of this method, such as the acidity of sample solution, the reductant of KBH4 and NaOH that served as the stabilizer of KBH4, were studied and these parameters were optimized. Bismuth was detected directly with the linear range of 0.00-44.00 ng.mL-1. The equation of working curve was A = 0.012 + 0.017c (c:ng.mL-1), r = 0.9995, the detection limit was 0.095 ng.mL-1 (3 sigma), and the recovery was 97.3%-103.3%. The method proposed has been used in the analysis of practical sample for bismuth with 96.6%-100.1% founded and 2.1% of RSD. Experiments showed that this method was simple, rapid, accurate and suitable for the assay of bismuth in bismuth pectin.

[Study on the determination of manganese in the Polygonum multiflorum by flame atomic absorption spectrometry].

This paper presents a method for the determination of manganese in the organism of the Chinese herbal medicine of the Polygonum multiflorum. Manganese was complexes, extracted and determined by FAAS. The opimum condition of experiment was studied. The accuracy and the detection limit were 7.6 and 8.4 ng.mL-1 respectively. The Mn was determined in range of 0.00-2.00 micrograms.mL-1. The relative standard deviation was 1.77%.