Phase-Selective Syntheses of Cobalt Telluride Nanofleeces for Efficient Oxygen Evolution Catalysts.

Cobalt-based nanomaterials have been intensively explored as promising noble-metal-free oxygen evolution reaction (OER) electrocatalysts. Herein, we report phase-selective syntheses of novel hierarchical CoTe2 and CoTe nanofleeces for efficient OER catalysts. The CoTe2 nanofleeces exhibited excellent electrocatalytic activity and stablity for OER in alkaline media. The CoTe2 catalyst exhibited superior OER activity compared to the CoTe catalyst, which is comparable to the state-of-the-art RuO2 catalyst. Density functional theory calculations showed that the binding strength and lateral interaction of the reaction intermediates on CoTe2 and CoTe are essential for determining the overpotential required under different conditions. This study provides valuable insights for the rational design of noble-metal-free OER catalysts with high performance and low cost by use of Co-based chalcogenides.

Hollow ternary PtPdCu nanoparticles: a superior and durable cathodic electrocatalyst.

Hollow alloyed nanoparticles (NPs) represent one kind of promising fuel cell electrocatalyst. However, the formation of single-cavity hollow structures by a dealloying process is quite challenging owing to the random leaching/dissolution of transition metals, surface passivation and the limited diffusion distance of the noble metals. Here we present a facile method to prepare hollow PtPdCu NPs derived from monodisperse alloy NPs by an acetic acid-assisted dealloying process. Here, acetic acid not only acts as a chemical etching agent but also plays an important role in the removal of the residual surfactants for colloidal NPs. Our findings rectify the current knowledge that hollow alloyed NPs cannot be prepared by a dealloying strategy and provide further understanding of the dealloying process in a ternary system. Such unique hollow ternary PtPdCu NPs exhibit outstanding durability and improved catalytic activity toward the oxygen reduction reaction.

Pt-Ni alloyed nanocrystals with controlled architectures for enhanced methanol oxidation.

Pt-Ni alloy nanocrystals with controlled architectures (multi-arms and flowers) have been synthesized via a simple colloid chemistry method. The crystal surfaces possess abundant low-coordination defect sites, where the reaction kinetics of methanol oxidation can be improved, resulting in the catalysts exhibiting better stability and higher resistance to poisoning.

Ultrathin PtPdTe nanowires as superior catalysts for methanol electrooxidation.

Ultrathin and ultralong: Highly uniform, ultrathin (diameter 5-7 nm), and ultralong (aspect ratio >10(4)) PtPdTe nanowires (NWs) were synthesized by using a facile method employing Te NWs as both sacrificial templates and reducing agents. Fine-tuning of the molar ratios of Pt and Pd precursors afforded PtPdTe NWs with different compositions and enhanced electroactivity in the methanol oxidation reaction in comparison with a commercial Pt/C catalyst.

Engineering interface and surface of noble metal nanoparticle nanotubes toward enhanced catalytic activity for fuel cell applications.

In order for fuel cells to have commercial viability as alternative fuel sources, researchers need to develop highly active and robust fuel cell electrocatalysts. In recent years, the focus has been on the design and synthesis of novel catalytic materials with controlled interface and surface structures. Another goal is to uncover potential catalytic activity and selectivity, as well as understand their fundamental catalytic mechanisms. Scientists have achieved great progress in the experimental and theoretical investigation due to the urgent demand for broad commercialization of fuel cells in automotive applications. However, there are still three main problems: cost, performance, and stability. To meet these targets, the catalyst needs to have multisynergic functions. In addition, the composition and structure changes of the catalysts during the reactions still need to be explored. Activity in catalytic nanomaterials is generally controlled by the size, shape, composition, and interface and surface engineering. As such, one-dimensional nanostructures such as nanowires and nanotubes are of special interest. However, these structures tend to lose the nanoparticle morphology and inhibit the use of catalysts in both fuel cell anodes and cathodes. In 2003, Rubinstein and co-workers proposed the idea of nanoparticle nanotubes (NNs), which combine the geometry of nanotubes and the morphology of nanoparticles. This concept gives both the high surface-to-volume ratio and the size effect, which are both appealing in electrocatalyst design. In this Account, we describe our developments in the construction of highly active NNs with unique surface and heterogeneous interface structures. We try to clarify enhanced activity and stability in catalytic systems by taking into account the activity impact factors. We briefly introduce material structural effects on the electrocatalytic reactivity including metal oxide/metal and metal/metal interfaces, dealloyed pure Pt, and mixed Pt/Pd surfaces. In addition, we discuss the geometric structure and surface composition changes and evolutions on the activity, selectivity, and stability under fuel cell operation conditions. We expect that these nanostructured materials with particular nanostructured characteristics, physical and chemical properties, and remarkable structure changes will offer new opportunities for wide scientific communities.

One-pot synthesis of branched palladium nanodendrites with superior electrocatalytic performance.

Branched Pd nanodendrites have been synthesized by a very simple method, which have displayed substantially enhanced oxygen reduction reaction (ORR) activity compared with that of commercial Pd/C catalysts. The Pd nanodendrites show 4.8 times more activity on the basis of an equivalent noble metal mass for the ORR than the commercial Pd/C catalysts. Moreover, the Pd nanodendrite catalysts also exhibit superior ethanol oxidation reaction (EOR) activity, making them excellent candidates as high performance multifunctional catalysts for both ORR and EOR.

Direct evidence for active site-dependent formic acid electro-oxidation by topmost-surface atomic redistribution in a ternary PtPdCu electrocatalyst.

The active site-dependent electrochemical formic acid oxidation was evidenced by the increased coverage of Pt in the topmost mixed PtPd alloy layer of ternary PtPdCu upon potential cycling, which demonstrated two catalytic pathways only in one catalyst owing to surface atomic redistribution in an acidic electrolyte environment.

Completely green synthesis of colloid Adams' catalyst α-PtO2 nanocrystals and derivative Pt nanocrystals with high activity and stability for oxygen reduction.

We report a first solution strategy for controlled synthesis of Adams' catalyst (i.e., α-PtO(2)) by a facile and totally green approach using H(2)PtCl(6) and water as reactants. The prepared α-PtO(2) nanocrystals (NCs) are ultrasmall in size and have very "clean" surfaces, which can be reduced to Pt NCs easily in ethanol under ambient conditions. Such Adams' catalysts have been applied as electrocatalysts beyond the field of heterogeneous catalysis. Noticeably, the water-only synthesized α-PtO(2) NCs and their derivative Pt NCs all exhibit much higher oxygen reduction reaction (ORR) activities and stabilities than that of the state-of-art Pt/C electrocatalysts. This study provides an example on the organics-free synthesis of α-PtO(2) and Pt NCs as promising cathode catalysts for fuel cell applications and, particularly, this simple, straightforward method may open a new way for the synthesis of other "clean" functional nanomaterials.

In situ controlled synthesis of thermosensitive poly(N-isopropylacrylamide)/Au nanocomposite hydrogels by gamma radiation for catalytic application.

Thermosensitive poly(N-isopropylacrylamide) (PNIPAM)/Au nanoparticle (NP) nanocomposite hydrogels are synthesized by in situ γ-radiation-assisted polymerization of N-isopropylacrylamide monomer aqueous solution in the presence of HAuCl4·4H2O. In this reaction, the PNIPAM hydrogels and the Au NPs are formed simultaneously, thus demonstrating an easy and straightforward synthetic strategy for the preparation of a uniform nanocomposite. The results suggest that increasing the monomer content during the preparation of nanocomposite materials can increase the sizes of Au NPs. The effects of irradiation dose and concentration of HAuCl4·4H2O on the optical and thermal properties of the hydrogel are also investigated. The PNIPAM/Au nanocomposite hydrogels act as an excellent catalyst for the conversion of o-nitroaniline to 1,2-benzenediamine, and the catalytic activity of the composite hydrogel can be tuned by the volume transition of PNIPAM. The in situ polymerization of monomer and reduction of metal ions initiated by a "clean" and "green" γ-radiation technique can be extended to the efficient synthesis of other nanocomposite materials.

Synthesis of an attapulgite clay@carbon nanocomposite adsorbent by a hydrothermal carbonization process and their application in the removal of toxic metal ions from water.

A new kind of attapulgite clay@carbon (ATP@C) nanocomposite adsorbent has been synthesized by a one-pot hydrothermal carbonization process under mild conditions using two cheap, ecofriendly materials (i.e., attapulgite clay (ATP), which is a magnesium aluminum silicate that is abundant in nature, and glucose, which is a green chemical obtained from biomass). Compared to carbon-based materials, this new ATP@C nanocomposite exhibits a high adsorption ability for Cr(VI) and Pb(II) ions with maximum adsorption capacities of 177.74 and 263.83 mg·g(-1), respectively. The results demonstrate that this nanocomposite is an exceptionally promising candidate as a low-cost, sustainable, and effective adsorbent for the removal of toxic ions from water.

Remarkable enhancement of electrocatalytic activity by tuning the interface of Pd-Au bimetallic nanoparticle tubes.

The interface, which formed in a bimetallic system, is a critical issue to investigate the fundamental mechanism of enhanced catalytic activity. Here, we designed unsupported Pd-Au bimetallic nanoparticle tubes with a tunable interface, which was qualitatively controlled by the proportion of Pd and Au nanoparticles (NPs), to demonstrate the remarkably enhanced effect of Pd and Au NPs in electro-oxidation of ethanol. The results demonstrated that the electrocatalytic activity is highly relative to the interface and has no direct relation with individual metal component in the Pd-Au system. This effect helps us in achieving a fundamental understanding of the relationship between their activity and the interface structure and chemical properties and, consequently, is helpful in designing new catalysts with high performances.

A general approach to electrochemical deposition of high quality free-standing noble metal (Pd, Pt, Au, Ag) sub-micron tubes composed of nanoparticles in polar aprotic solvent.

A family of free-standing noble metal (Pd, Pt, Au, Ag) sub-micron tubes composed of nanoparticles (STNs) can be synthesized by a one-step electrochemical route in anhydrous dimethyl sulfoxide (DMSO) solution without addition of any other surfactants.

[Establishment of method collecting peripheral blood hematopoietic stem/progenitor cells from infants].

The aim of this study was to explore a safe method collecting peripheral blood stem/progenitor cell (PBSPC) from the infants of body weight less than 20 kg by using the COBE Spectra Blood Cell Separator through Auto-PBSC procedure. After washing tube by normal saline, one unit of irradiated RBC was infused into the apheresis set. When the collection terminated, only the concentrated RBC in the apheresis set was returned to the infant. The peripheral mononuclear cells (PBMNCs) and CD34+ cells were counted, the cell viability was determined. The results showed that 13 PBSPC collections were carried out successfully from 7 infants of body weight<20 kg. The average count of MNCs was 4.44x10(8)/kg [(3.46-6.45)x10(8)/kg], the CD34+ count was 2.20x10(6)/kg [(1.34-3.79)x10(6)/kg] and the cell viability was 98.45% (97%-100%) respectively. The vital signs of all the infants went smoothly during collection of PBSPCs. In conclusion, with the aid of COBE Spectra blood cell separator and other measures, the collection of PBSPCs from infants of body weight<20 kg is safe and effective, the PBMNCs containing enough PBSPC can be harvested for transplantation.