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1.
ACS Appl Mater Interfaces ; 13(21): 24682-24691, 2021 Jun 02.
Artigo em Inglês | MEDLINE | ID: mdl-34009947

RESUMO

Developing a high-performance nonprecious metal electrocatalyst for water splitting is a strong demand for the large-scale application of electrochemical H2 production. In this work, we design a facile and scalable strategy to activate titanium metal for the hydrogen evolution reaction (HER) in alkaline media through incorporating hydrogen into the α-Ti crystal lattice by H2 plasma bombardment. Benefiting from the accelerated charge transfer and enlarged electrochemical surface area after H2 plasma treatment, the H-incorporated Ti shows remarkably enhanced HER activity with a much lower overpotential at -10 mA cm-2 by 276 mV when compared to the pristine Ti. It is revealed that the retention of the incorporated H(D) atoms in the Ti crystal lattice during HER accounts for the durable feature of the catalyst. Density functional theory calculations demonstrate the effectiveness of hydrogen incorporation in tuning the adsorption energy of reaction species via charge redistribution. Our work offers a novel route to activate titanium or other metals by H incorporation through a controllable H2 plasma treatment to tune the electronic structure for water splitting reactions.

2.
Inorg Chem ; 58(19): 13066-13076, 2019 Oct 07.
Artigo em Inglês | MEDLINE | ID: mdl-31556292

RESUMO

Cerium oxides are prevalent catalytic materials, and the lanthanide-doped ceria have attracted special interest since it is easy to tune the concentration of oxygen vacancies (VO) by changing the doping content. The presence of VO is generally believed to favor a catalytic reaction, but the formation of dopant-vacancy associations at a high doping concentration might produce an adverse effect. Herein, evolutions of the structural properties and catalytic performances in Sm-doped ceria (SmxCe1-xO2-δ, x = 0-1) are investigated to explore the doping effect of Sm3+ on the ceria-based nanoctrystals. The SmxCe1-xO2-δ films composed of nanoctrystals are elaborately prepared via electrodeposition under mild conditions to prevent phase separation. A combination of studies, including scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Raman, photoluminescence (PL), and methanol electro-oxidation (MEO) reaction, reveals that variation trends for the VO concentration and catalytic property of SmxCe1-xO2-δ are unsynchronized. The lattice structures of SmxCe1-xO2-δ nanoctrystals undergo a smooth and steady transition from F-type (fluorite CeO2) to C-type (cubic Sm2O3) with the increase of Sm3+ contents. The structural transition occurs in the Sm3+ concentration range of 64-84%, within which the VO concentration reaches the maximum as well. However, the optimal MEO performance is obtained at a relatively lower doping concentration of 24%. Above this concentration, significant dopant-vacancy associates are observed by XRD, Raman, and PL characterizations. It is inferred that, for these ceria-based nanocrystals, the dopant-vacancy association induced by high doping would impede the growth of catalytic performance despite all the benefits of VO.

3.
ChemistryOpen ; 8(7): 1027-1032, 2019 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-31367510

RESUMO

Developing cost-effective and highly efficient oxygen evolution reaction (OER) electrocatalysts is vital for the production of clean hydrogen by electrocatalytic water splitting. Here, three dimensional nickel-iron layered double hydroxide (NiFe LDH) nanosheet arrays are in-situ fabricated on self-supporting nitrogen doped graphited foam (NGF) via a one-step hydrothermal process under an optimized amount of urea. The as prepared NiFe LDH/NGF electrode exhibits a remarkable activity toward OER with a low onset overpotential of 233 mV and a Tafel slope of 59.4 mV dec-1 as well as a long-term durability. Such good performance is attributed to the synergy among the doping effect, the binder-free characteristic, and the architecture of the nanosheet array.

4.
Inorg Chem ; 55(21): 10835-10838, 2016 Nov 07.
Artigo em Inglês | MEDLINE | ID: mdl-27726341

RESUMO

Uranium nitrides are among the most promising fuels for Generation IV nuclear reactors, but until now, very little has been known about their thermal stability properties under nonequilibrium conditions. In this work, thermal decomposition of nitrogen-rich uranium nitride (denoted as UN2-x) under ultrahigh-vacuum (UHV) conditions was investigated by thermal desorption spectroscopy (TDS). It has been shown that the nitrogen TDS spectrum consists of two peaks at about 723 and 1038 K. The X-ray diffraction, scanning electron microscopy, and X-ray photoelectron microscopy results indicate that UN2-x (UN2 phase) decomposed into the α-U2N3 phase in the first step and the α-U2N3 phase decomposed into the UN phase in the second step.

5.
Sci Rep ; 6: 19870, 2016 Jan 29.
Artigo em Inglês | MEDLINE | ID: mdl-26822226

RESUMO

The catalyst-free growth of nanocrystals on various substrates at room temperature has been a long-standing goal in the development of material science. We report the growth of one-dimensional zinc nanocrystals on silicone oil surfaces by thermal evaporation method at room temperature (20 ± 2 °C). Uniform zinc nanorods with tunable size can be obtained. The typical length and width of the nanorods are 250-500 nm and 20-40 nm, respectively. The growth mechanism can be attributed to the effect of the liquid substrate and the preferential growth direction of the crystals. This result provides a novel and simple way to fabricate the precursors (zinc crystals) for preparation of Zn-based semiconductors and other metallic crystals on liquid substrates.

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