Xian Jiang

Arginine-Assisted Synthesis and Catalytic Properties of Single-Crystalline Palladium Tetrapods

Noble metallic nanocrystals (NMNCs) with highly branched morphologies are an exciting new class of nanomaterials because of their great potential application in catalysis, sensing, optics, and electronics originating from their unique structures. Herein, we report a facile water-based method to synthesize high-quality palladium (Pd) tetrapods with the assistance of arginine molecule, which is more economical and environmentally friendly than the previous reported carbon monoxide (CO)-assisted synthesis in the organic system. During the synthesis, arginine molecule plays an essential role in controlling the tetrapod-like morphology. The as-synthesized Pd tetrapods have a potential application in the formic acid (HCOOH)-induced reduction of highly toxic hexavalent chromium (Cr(VI)) owing to their improved catalytic performance for the HCOOH decomposition.

Polyallylamine Functionalized Palladium Icosahedra: One-Pot Water-Based Synthesis and Their Superior Electrocatalytic Activity and Ethanol Tolerant Ability in Alkaline Media

Polyallylamine (PAH) functionalized Pd icosahedra are synthesized through a simple, one-pot, seedless and hydrothermal growth method. Herein, PAH is used efficiently as a complex-forming agent, capping agent, and facet-selective agent. The strong interaction between PAH and Pd atom sharply changes the electronic structure of Pd atom in the Pd icosahedra. The protective function of PAH layers and enhanced antietching capability of Pd atom are responsible for the formation of the Pd icosahedra. Very importantly, the as-prepared PAH functionalized Pd icosahedra exhibit superior electrocatalytic activity and ethanol tolerant ability toward the oxygen reduction reaction (ORR) compared to the commercially available Pt black in alkaline media. At 0.95 V (vs RHE), the ORR specific kinetic current density at the Pd icosahedra is 4.48 times higher than that at commercial Pt black. The fact demonstrates the appropriate surface modification of the Pd nanoparticles by nonmetallic molecules can be regarded as an effective way to enhance the electrocatalytic activity toward the ORR.

Ultrathin AgPt alloy nanowires as a high-performance electrocatalyst for formic acid oxidation

To address the insufficient electrocatalytic activity and stability of formic acid oxidation reaction (FAOR) electrocatalysts, as well as their high cost, we herein demonstrate the facile hydrothermal synthesis of ultrathin AgPt alloy nanowires using amine-terminated poly(N-isopropylacrylamide) (PNIPAM-NH2) as a structure-directing agent. The initial generation of AgCl precipitates, subsequent formation of AgPt nanoparticles, and their oriented attachment account for the formation of ultrathin AgPt alloy nanowires. Benefiting from their unique 1D anisotropy and alloyed composition, the prepared ultrathin AgPt nanowires exhibit a superior electrocatalytic activity and better CO tolerance for the FAOR, reaching a 1.6-fold and 3.7-fold higher specific current density than AgPt nanoparticles and a commercial Pt black catalyst, respectively. Additionally, the ultrathin AgPt alloy nanowires manifest a superior electrochemical stability and structural robustness during electrocatalysis, making them a promising FAOR electrocatalyst. This work not only provides a reliable strategy for the synthesis of noble metal-based ultrathin nanowires, but also opens an avenue towards the rational design of efficient electrocatalysts for fuel cell systems.

PtCu nanodendrite-assisted synthesis of PtPdCu concave nanooctahedra for efficient electrocatalytic methanol oxidation

Ternary PtPdCu alloy concave nanooctahedra (ACNOs) are synthesized by a facile “one-pot, two-step” method from PtCu nanodendrites. The as-prepared PtPdCu ACNOs show superior electrocatalytic activity and durability for the methanol oxidation reaction (MOR) compared with binary PtCu alloy nanodendrites and commercial Pt black.

Robust bifunctional oxygen electrocatalyst with a “rigid and flexible” structure for air-cathodes

The development of highly active air-cathodes with robust stability and a low price is of crucial significance for rechargeable Zn–air batteries and remains a great challenge. Herein, for the first time, we report a “rigid and flexible” material consisting of three-dimensional (3D) porous nickel-manganese oxide (Ni6MnO8) coupled with 1D ultrathin Au nanowires (Au-NWs) as an efficient bifunctional oxygen electrocatalyst, adopting α-naphthol-Au(III) as a precursor of Au-NWs and pre-formed Ni6MnO8 as a support. Ni6MnO8 acts not only as a robust carbon-free support that is stable in alkaline electrochemical conditions, but also as a highly active component for the oxygen evolution reaction (OER), while flexible Au-NWs contribute to the excellent oxygen reduction reaction (ORR) activity and act as a flexible conductive electronic network. The coupling of Ni6MnO8 and Au-NWs plays a complementary role in the two types of oxygen electrocatalytic reactions. Accordingly, their advantages have been optimally harnessed while overcoming their deficiencies. Moreover, a Zn–air battery assembled with such a rigid and flexible air-cathode has lower charge and discharge overpotentials and a higher cyclic stability than those with a mixed Pt/C+RuO2 catalyst.Electrocatalysis: getting more out of thin airA hybrid material that improves the performance of zinc–air batteries has been developed by researchers in China and Singapore. Metal–air batteries, in which one electrode is made from a metal while the other reacts with oxygen in ambient air, can hypothetically store much more energy per unit mass than other types of rechargeable device but this improved performance has not yet been demonstrated. Yawen Tang from the Nanjing Normal University, China, Jong-Min Lee from the Nanyang Technological University, Singapore, and colleagues have developed an improved air-cathode material made of rigid nickel-manganese oxide microspheres linked by flexible gold nanowires. The oxide material provides the required chemical versatility and stability, while the gold gives the hybrid material its electrical conductivity. A zinc–air battery assembled with this electrode exhibits excellent electrocatalytic performance.A hybrid material that improves the performance of zinc–air batteries has been developed by researchers in China and Singapore. Metal–air batteries, in which one electrode is made from a metal while the other reacts with oxygen in ambient air, can hypothetically store much more energy per unit mass than other types of rechargeable device but this improved performance has not yet been demonstrated. Yawen Tang from the Nanjing Normal University, China, Jong-Min Lee from the Nanyang Technological University, Singapore, and colleagues have developed an improved air cathode material made of rigid nickel-manganese oxide microspheres linked by flexible gold nanowires. The oxide material provides the required chemical versatility and stability, while the gold gives the hybrid material its electrical conductivity. A zinc–air battery assembled with this electrode exhibits excellent electrocatalytic performance.

FeOOH-Templated synthesis of hollow porous platinum nanotubes as superior electrocatalysts towards methanol electrooxidation

Metallic nanomaterials with a hollow and porous structure have attracted a great deal of interest in electrocatalysis due to their high surface area, abundant active-sites and improved metal utilization efficiency. Herein, we report an effective layer-by-layer assembly strategy to prepare a novel type of hollow porous Pt nanotube (Pt-NT) using polyelectrolyte-modified FeOOH nanorods as templates. To our knowledge, the utilization of FeOOH nanorods as templates to synthesise hollow porous Pt nanostructures has not been reported. The obtained Pt-NTs present the combined merits of a one-dimensional (1D) hollow architecture, a reactant accessible porous-surface and a large surface area (37.8 m2 g−1). As a result, superior catalytic activity and stability for the methanol oxidation reaction (MOR) are achieved with the Pt-NTs as an anode catalyst. Compared to a commercial Pt-black catalyst, the Pt-NTs exhibit a factor of 1.4 and 1.2 enhancement in mass activity (231 A g−1) and specific activity (11.8 A m−2) for the MOR, respectively.