Yuqiao Zeng

On the effect of impurities in metallic glass formation

We report atomic-scale characterization of impurity elements in a Pd40Ni40P20 metallic glass by state-of-the-art atom probe tomography combining with transmission electron microscopy. The significant partitioning of the impurities in heterogeneous nanocrystals of the primarily crystallized glass provides compelling evidence that minor impurities dramatically influence the stability of supercooled liquids by manipulating heterogeneous crystallization of metallic glasses.

Amorphous Alloy: Promising Precursor to Form Nanoflowerpot

Nanoporous copper is fabricated by dealloying the amorphous Ti2Cu alloy in 0.03 M HF electrolyte. The pore and ligament sizes of the nanoporous copper can be readily tailored by controlling the dealloying time. The as-prepared nanoporous copper provides fine and uniform nanoflowerpots to grow highly dispersed Au nanoflowers. The blooming Au nanoflowers in the nanoporous copper flowerpots exhibit both high catalytic activity and stability towards the oxidation of glucose, indicating that the amorphous alloys are ideal precursors to form nanoflowerpot which can grow functional nanoflowers.

Effects of Bias Voltage on Fen Films Prepared by Magnetron Sputtering

Iron nitride films were deposited by radio frequency (RF) reactive magnetron sputtering at different bias voltages. It was found that the composition, structure and magnetic properties of the iron nitride films were strongly dependent on the depositing bias voltage. With a bias voltage of –50 V, the iron nitride film is fully dense and has a homogenous microstructure consisting of α-Fe and Fe16N2, leading to a unique combination of high Ms of 1645 emu/cc, Hc of 5 Oe and μi of 1573.

Effects of Metallic Glass Precursors on the Catalytic Performance of Nanoporous Metals

This work reports the effects of metallic glass precursors on the catalytic performance of nanoporous metals. Pd-based multicomponent nanoporous metals with similar nanoporous structure were successfully fabricated by electrochemically dealloying the Pd20Ni60P17B3 and Pd20Ni20Cu40P17B3 metallic glass precursors at the critical dealloying potentials. It was found that the glassy precursors with different chemical compositions result in different doping elements in the as-obtained nanoporous metals and thus lead to different catalytic activities.

Pd based nanoporous metals with superior catalytic activity

Abstract This work reports the effects of metallic glass compositions on the compositions and catalytic activities of the dealloyed Pd based nanoporous metals (NPMs). The Pd10Ni70P20 and Pd10Ni50Co20P16B4 metallic glasses were potentiostatically dealloyed in an acid solution. The pore size of the as obtained NPMs is similar and <100 nm. The NPM dealloyed from Pd10Ni70P20 contains ∼89 at-% Pd, 8 at-% Ni and 3 at-% P. The NPM dealloyed from Pd10Ni50Co20P16B4 has 85 at-% Pd, 11 at-% Ni, 3 at-% Co and 1 at-% P. Both of the NPMs exhibit lower formic acid electro-oxidation potential when compared with the commercial Pd/C catalyst. It should be noticed that the NPM dealloyed from Pd10Ni50Co20P16B4 shows dramatically enhanced catalytic activity toward formic acid electro-oxidation, as is evidenced from the low formic acid electro-oxidation potential at 350 mV (versus RHE), which may contribute to the existence of proper amount of Ni and Co residuals in the NPM. The simultaneous addition of Ni and Co can remarkably increase the occupation of the lower unoccupied molecular orbital of the Pd clusters and thus improve the catalytic activity.

Enzyme-Free Electrochemical Glucose Sensors Prepared by Dealloying Pd-Ni-P Metallic Glasses

We report the formation of enzyme-free electrochemical glucose sensors by electrochemical dealloying palladium-containing Pd-Ni-P metallic glasses. When metallic glasses with different Pd contents are used as the dealloying precursor alloys, palladium-based nanoporous metals with different ligament and pore sizes can be obtained. The chemical compositions of the nanoporous metals also vary according to the different precursor compositions. All the as-obtained nanoporous metals exhibit electrochemical catalytic activity towards the oxidation of d-glucose, indicating that the nanoporous metals prepared by dealloying the Pd-Ni-P metallic glasses are promising materials for enzyme-free electrochemical glucose sensor.