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1.
Nanoscale ; 13(40): 17003-17010, 2021 Oct 21.
Artigo em Inglês | MEDLINE | ID: mdl-34617088

RESUMO

Refining the size of nanoparticles to exhibit larger specific surface areas and expose much more active sites is of great significance for enhancing the oxygen evolution reaction (OER) activity of the electrocatalyst, but still a tremendous challenge. Herein, a Cr-FeOOH@Ni2P-Ni5P4/NF (Cr-FeOOH@Ni-P/NF) catalyst was constructed by electrodepositing a layer of CrFe oxyhydroxides on the self-grown Ni-P nanoparticles, which exhibits ultrafine nanoparticles and thus superexcellent electrocatalytic OER performance. The final catalyst affords ultra-low overpotentials of 144 mV and 210 mV to achieve current densities of 10 and 50 mA cm-2, respectively. Meanwhile, it demonstrates robust stability for at least 80 hours with no activity decay. This strategy of refining nanoparticles on a three-dimensional electrode has once again been further demonstrated to be feasible and highly effective and opens a new door for the exploration of electrocatalysts with excellent comprehensive properties.

2.
Dalton Trans ; 50(42): 15094-15102, 2021 Nov 02.
Artigo em Inglês | MEDLINE | ID: mdl-34610629

RESUMO

Hydrogen production by electrocatalytic water splitting is a pollution-free, energy-saving, and efficient method. The low efficiency of hydrogen production, high overpotentials and expensive noble-metal catalysts have limited the development of hydrogen production from electrocatalytic water splitting. Therefore, the exploration of bifunctional electrocatalysts for water overall splitting to produce hydrogen is of profound significance. Herein, Ni3S2@Ni2P/MoS2 heterostructure electrocatalysts were synthesized on Ni foam through an environmentally friendly hydrothermal method and low-temperature phosphating method. The synergistic effects between different components and the mutual substitution principle between sulfur atoms and phosphorus atoms greatly improve the OER performance of the electrocatalyst. It is also an effective strategy to optimize the adsorption energies of intermediates by the design of heterostructured catalysts composed of multiple substances. Ni3S2@Ni2P/MoS2 only requires a low overpotential (η10) of 175 mV at a current density of 10 mA cm-2 in 1.0 M KOH solution and the stable duration exceeds 40 h. In addition, this heterogeneous structure is assembled into an electrolytic cell for overall water splitting, which exhibits a low cell voltage of 1.61 volts and retains the robust stability over 30 h at 10 mA cm-2. The Ni3S2@Ni2P/MoS2 heterostructure prepared in this research provides a strategy for exploring other heterostructured electrocatalysts with different components.

3.
Inorg Chem ; 60(19): 15041-15047, 2021 Oct 04.
Artigo em Inglês | MEDLINE | ID: mdl-34528788

RESUMO

A new alkali metal-rare earth metal anhydrous sulfate, KTb(SO4)2 (KTSO), was synthesized by a hydrothermal method. It crystallized in the non-centrosymmetric (NCS) orthorhombic space group P212121 with cell parameters a = 5.43950(10), b = 8.8579(3), c = 13.3962(4), Z = 2. Its structure is composed of [KO11], [TbO8], and [SO4] groups, which are interconnected to constitute a one-dimensional (1D) chain, and then further linked to construct a three-dimensional (3D) network structure through [SO4] units. The results of the powder frequency doubling test show that KTb(SO4)2 has a phase-matching second-order nonlinear optical effect of 0.3 times that of KH2PO4 (KDP). The measured birefringence of the crystal (0.01) agrees well with the calculated value (0.019). Meanwhile, its infrared and ultraviolet spectrum and thermal properties were studied, respectively. Its optical properties and band gap structure are studied by theoretical calculation. This work provides a NCS structure of anhydrous sulfates and offers guidance for further exploration of new anhydrous sulfates.

4.
Nanoscale ; 13(25): 11069-11076, 2021 Jul 07.
Artigo em Inglês | MEDLINE | ID: mdl-34132316

RESUMO

The exploration of efficient non-noble metal electrocatalysts for hydrogen evolution reaction has received considerable attention to replace commercial Pt catalyst. It is known that the cooperative coupling of appropriate non-noble metals exhibits excellent HER performance than a single component. Herein, an Mn-doped NiCoP flower-like electrocatalyst with self-assembled nanosheets on a nickel foam is synthesized via successive hydrothermal methods, followed by low temperature phosphidation. The as-synthesized Mn-NiCoP presents extraordinarily high catalytic activity and robust chemical stability towards the hydrogen evolution reaction in both acidic and alkaline electrolytes. Benefiting from the dual modulation of the morphology structure and chemical compositions, Mn-NiCoP/NF achieves a current density of 10 mA cm-2 at a low overpotential of 37 mV for HER in a 0.5 M H2SO4 solution. Moreover, it only requires overpotentials of 67 mV and 142 mV to deliver current densities of 10 mA cm-2 and 50 mA cm-2 in a 1 M KOH solution, respectively. Remarkably, it holds enhanced stability in 1 M KOH, maintaining HER activity for at least 120 h with negligible overpotential decay. The highly efficient and stable Mn-NiCoP electrocatalyst is valuable in applications relevant to energy storage.

5.
Dalton Trans ; 49(47): 17414-17420, 2020 Dec 15.
Artigo em Inglês | MEDLINE | ID: mdl-33216082

RESUMO

Three novel lanthanide-biradical complexes {[Ln(hfac)3]2(mbisNITPyPh)(H2O)}{[Ln(hfac)3](mbisNITPyPh)}·CHCl3 (1-Gd; 2-Tb; 3-Dy) were successfully achieved by reacting the biradical mbisNITPyPh (5-(3-pyridyl)-1,3-bis(1-oxyl-3'-oxido-4',4',5',5'-tetramethyl-4,5-hydro-1H-imidazol-2-yl)benzene) with Ln(hfac)3·2H2O (hfac = hexafluoroacetylacetonate). These Ln-biradical complexes consist of two kinds of spin moieties, namely, dinuclear {[Ln(hfac)3]2(mbisNITPyPh)(H2O)} and mononuclear {[Ln(hfac)3](mbisNITPyPh)}, in which two adjacent dinuclear units are linked by intermolecular hydrogen bonds involving the uncoordinated nitroxide units and the coordinated water molecules of Ln ions, forming a cyclic tetranuclear structure unit. The magnetization study reveals that intramolecular Ln(iii)-coordinated NO ferromagnetic interactions are dominant in the present system. Moreover, the clear frequency dependence of ac magnetic susceptibilities of complex 3-Dy is indicative of slow relaxation of magnetization behavior, indicating its single-molecule magnet nature.

6.
J Colloid Interface Sci ; 577: 379-387, 2020 Oct 01.
Artigo em Inglês | MEDLINE | ID: mdl-32497919

RESUMO

Developing highly efficient and low-cost electrocatalysts with superior durability for hydrogen evolution reaction (HER) is a big challenge. Here, we design and fabricate a highly efficient electrocatalyst with unique three-dimensional (3D) porous peony-like micro-flower Mn-CoP nano-structure on flexible carbon cloth (Mn-CoP PMFs/CC), which exhibits high electrocatalytic activity toward the HER in both acid and alkaline circumstances. Remarkably, benefiting from the unique 3D porous structure with large surface areas, good electron conductivity for fast electron transport, and effective channels for the release of gas, the resultant catalyst exhibits an ultra-low overpotential of 28 and 90 mV to arrive the current density of 10 mA/cm2 in 0.5 M H2SO4 and 1.0 M KOH solutions, respectively. Meanwhile, the Mn-CoP PMFs/CC material shows small Tafel slopes and good long-term stability in acid and alkaline media. Density Functional Theory (DFT) calculations illustrate that Mn doping indeed improve electron transfer, and makes the thermo-neutral hydrogen adsorption free energy (ΔGH*) of CoP on the surface of (0 1 1) sharply close to zero, which is very conducive to the adsorption and desorption of hydrogen, thereby making Mn-CoP PMFs/CC with significant enhanced electrocatalytic HER performance. Our 3D porous electrocatalyst has greatly promoted the efficient electrolysis of water to produce hydrogen.

7.
Chem Commun (Camb) ; 56(36): 4894-4897, 2020 May 05.
Artigo em Inglês | MEDLINE | ID: mdl-32236257

RESUMO

Organic-inorganic halide hybrids are rapidly gaining increased attention owing to their remarkable optoelectronic performance. Amongst these, divalent and trivalent metal cations (Pb2+, Sn2+, Bi3+, and Sb3+) usually link to six halogen X atoms and form an asymmetric [MX6] octahedron with weak optical anisotropy. Herein, we show a first family of monovalent-metal-based hybrid halides [N(CH3)4]MCl2 (M = Ga, In) with a zero-dimensional configuration containing unprecedented linear [MX2] units. Owing to the reduced coordination number, the lone pairs on Ga+ and In+ exhibit quasi-two-dimensional distribution, thereby leading to a narrowed bandgap, enhanced optical anisotropy and strong nonlinear second harmonic response of 1.4 and 1.3 times that of benchmark KH2PO4, respectively.

8.
Chem Asian J ; 2018 Jun 11.
Artigo em Inglês | MEDLINE | ID: mdl-29888868

RESUMO

Searching for efficient, low-cost, and durable electrocatalysts toward the hydrogen evolution reaction (HER) is extremely urgent for future energy conversion systems. Herein, the colloidal synthesis of 2D tungsten-doped nickel selenide nanosheets by using Ni(acac)2 (acac=aceylacetonate), [W(CO)6 ], and selenium powder as precursors in oleylamine is reported. The introduction of tungsten is essential for the formation of 2D nanosheets. As a result, by taking the advantage of the unique layered structure and strong synergistic electronic effect between nickel, tungsten, and selenium, the as-synthesized Ni0.54 W0.26 Se nanosheets exhibit superior catalytic activity toward the HER in alkaline media, with an overpotential of 162 mV (η10 ), which is much lower than those of NiSe2 (η10 =330 mV) and WSe2 (η10 =378 mV), and higher than that of most previously reported selenide-based electrocatalysts.

9.
Chem Asian J ; 12(22): 2967-2972, 2017 Nov 16.
Artigo em Inglês | MEDLINE | ID: mdl-28949097

RESUMO

The design of high-performance catalysts for hydrogen generation is highly desirable for the upcoming hydrogen economy. Herein, we report the colloidal synthesis of nanocuboid Ni2 P by the thermal decomposition of nickel chloride hexahydrate (NiCl2 ⋅6 H2 O) and trioctylphosphine. The obtained nanocuboid Ni2 P was characterized by using powder X-ray diffraction, transmission electron microscopy, energy-dispersive X-ray spectroscopy, X-ray photoelectron spectroscopy, and inductively coupled plasma atomic emission spectroscopy. For the first time, the as-synthesized nanocuboid Ni2 P is used as a bifunctional catalyst for hydrogen generation from the hydrolysis of ammonia borane and electrocatalytic hydrogen evolution. Owing to the strong synergistic electronic effect between Ni and P, the as-synthesized Ni2 P exhibits catalytic performance that is superior to its counterpart without P doping.

10.
Nanoscale ; 9(20): 6821-6825, 2017 May 25.
Artigo em Inglês | MEDLINE | ID: mdl-28497144

RESUMO

The search for highly efficient non-precious metal electrocatalysts toward the oxygen evolution reaction (OER) is extremely essential for renewable energy systems. Here, we report the colloidal synthesis of Fe doped NiSe2, which functions as a high-performance electrocatalyst for the OER in alkaline solution. The NiFeSe catalysts are composed of urchin-like dendrites with a high number of active sites, which could provide fast transportation of electrons and electrolytes, and facile release of the evolved O2 bubbles during the OER catalysis. Benefitting from this unique urchin-like structure and strong electron interaction between Fe, Ni, and Se, the Ni1.12Fe0.49Se2 catalyst exhibits excellent electrocatalytic activity and high durability toward the OER in alkaline solution, with an overpotential of 227 mV at a current density of 10 mA cm-2, which is, to the best of our knowledge, higher than most of the reported selenide-based electrocatalysts.

11.
ACS Appl Mater Interfaces ; 7(2): 1031-4, 2015 Jan 21.
Artigo em Inglês | MEDLINE | ID: mdl-25559434

RESUMO

Ultrafine monodisperse bimetallic NiPt nanoparticles with different compositions have been successfully synthesized by coreduction of nickel acetylacetonate and platinum acetylacetonate with borane-tert-butylamine in oleylamine. Among all the catalysts tested, Ni84Pt16/graphene exhibited 100% hydrogen selectivity, and marked high catalytic activity, with TOF values of 415 h(-1) at 50 °C, and 133 h(-1) at 25 °C for hydrogen generation from alkaline solution of hydrazine.

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