Agar-induced hollow porous carbon nanospheres anchored platinum for high-performance hydrogenation.

Hollow porous carbon has attracted a great deal of interest as catalyst-support because of its high surface area, low density and large pore volume. Herein, we develop a layer-by-layer assembly method to effectively load Pt nanoparticles on hollow porous carbon nanospheres (Pt/HPC) through using modified-SiO2 nanospheres as the template and agar as the carbon resource. The gel properties of agar (e.g., sensitivity to temperature and high mechanical strength) makes the Pt nanoparticles well crosslink with carbon, as well as endows the carbon nanospheres with robust stability. The synthesized Pt/HPC was employed as a catalyst in the hydrogenation reduction of rhodamine B (RhB). The catalytic results demonstrate that Pt/HPC is very promising for RhB hydrogenation as compared to commercial Pt/C catalyst. It is proven that such excellent activity of Pt/HPC can be attributed to the combined merits of hollow porous architecture and well combination between HPC and Pt nanoparticles.

Atom-Ratio-Conducted Tailoring of PdAu Bimetallic Nanocrystals with Distinctive Shapes and Dimensions for Boosting the ORR Performance.

Systematically manipulating the shape, dimension, and surface structure of PdAu nanocrystals is an active subject because it offers a powerful means to regulate and investigate their structure-activity relationship. Meanwhile, it is still urgent to reduce the use of two-dimensional precious-metal-based nanomaterials. This work demonstrates that PdAu nanocrystals with a variety of shapes/dimensions, including 1D anisotropic nanowires, 2D porous nanosheets, and 3D penetrative nanoflowers, can be systematically synthesized by simply adjusting the atomic ratio or the reaction time in the same protocol. The resultant PdAu nanocrystals with distinctive shapes, but the same building blocks triumphantly avoid the effects of facet and surface properties; this represents an ideal platform for directly comparing the oxygen reduction reaction (ORR) activity. 2D porous PdAu nanosheets demonstrate superior ORR performance (Eonset = 1.040 V, E1/2 = 0.932 V) compared with other-dimension-based samples and commercial Pd black; this is attributed to the abundant surface atoms and omni-directional mass-transfer channels. This work not only paves the way for systematically measuring a series of distinctive PdAu nanocrystals as non-Pt electrocatalysts, but also sheds light on the study of structures/dimensions in tuning the catalytic properties of bimetallic nanocrystals.

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.

Preparation of hemocompatible cellulosic paper based on P(DMAPS)-functionalized surface.

The surface-modification of paper substrates with functional layers is gaining increasing interest, both from academic and industrial research. In this case, the cellulosic paper (CP) surface was functionalized with zwitterionic poly-(3-dimethyl(methacryloyloxyethyl) ammoniumpropane sulfonate) (CP-g-P(DMAPS) via surface-initiated atom transfer radical polymerization (ATRP) technique for enhancing blood compatibility. An obvious increase in graft yield of the functional P(DMAPS) with polymerization time was observed. The new CP-g-P(DMAPS) produced was investigated for its hemocompatibility. The hemocompatibility studied including platelet and whole blood ceels adhesion tests, hemolysis assay, morphological changes of red blood cells (RBCs), coagulation time tests, and complement activation, platelet activation at the molecular level. Most assays had remarkable differences in the presence of the new zwitterionic CP, indicated the importance of the zwitterion for hemocompatibility of CP.