Nickel-Doped Sodium Cobaltite 2D Nanomaterials: Synthesis and Electrocatalytic Properties

Azor, Alberto; Ruiz‐González, M. Luisa; Gonell, Francisco; Laberty-Robert, Christel; Parras, M.; Sánchez, Clément; Portehault, David; González‐Calbet, José M.

doi:10.1021/acs.chemmater.8b01146

Cited by 18 publications

(10 citation statements)

References 46 publications

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“…[28][29][30] As shown in Part 2.3 of Supporting Information (SI) and Table S3, the L3/L2 ratio of region 1 and 2 increases from 2.83 to 3.67, indicating the decreased oxidation states of Ni. [31][32][33][34] This coincides with the normalized white line intensity of Ni (I3d) decrease from 0.92 to 0.67, advocating the increased electron occupancy on 3d orbit. [31][32][33][34] The core-loss edges at 194.7 eV and a broad peak at 203.9…”

Section: Sample Preparation Procedures Is Illustrated Insupporting

confidence: 77%

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Boron leaching: Creating vacancy-rich Ni for enhanced hydrogen evolution

Han

Wang

et al. 2021

Nano Res.

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Creating vacancy is often highly effective in enhancing the hydrogen evolution performance of transition metal-based catalysts. Vacancy-rich Ni nanosheets has been fabricated via topochemical formation of 2D Ni2B on graphene precursor followed by boron leaching.Anchored on graphene, a few atomic layered Ni2B nanosheets are first obtained by reduction and annealing. Large number of atomic vacancies are then generated in the Ni2B layer via leaching boron atoms. When used for hydrogen evolution reaction (HER), the vacancy-rich Ni/Ni(OH)2 heterostructure nanosheets demonstrate remarkable performance with a low overpotential of 159 mV at a current density of 10 mA•cm -2 in alkaline solution, a dramatic improvement over 262 mV of its precursor. This enhancement is associated with the formation of vacancies which introduce more active sites for HER along Ni/Ni(OH)2 heterointerfaces. This work offers a facile and universal route to introduce vacancies and improve catalytic activity. TOC GRAPHICSHydrogen is a promising energy carrier since it has high energy density, is naturally abundant, and produces no pollutants when consumed. 1-2 Hydrogen evolution reaction (HER) via water electrolysis has long been considered as the most sustainable way to produce hydrogen; but the

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Section: Sample Preparation Procedures Is Illustrated Insupporting

confidence: 77%

“…[31][32][33][34] This coincides with the normalized white line intensity of Ni (I3d) decrease from 0.92 to 0.67, advocating the increased electron occupancy on 3d orbit. [31][32][33][34] The core-loss edges at 194.7 eV and a broad peak at 203.9…”

Section: Sample Preparation Procedures Is Illustrated Insupporting

confidence: 77%

Boron leaching: Creating vacancy-rich Ni for enhanced hydrogen evolution

Han

Wang

et al. 2021

Nano Res.

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“…30 The stacking of these layers is dominated by electrostatic interactions between the cobalt oxide layers and the intercalated Li + cations. 13 Due to the strong cohesive nature of LCO from this electrostatic stabilization, two-step chemical exfoliation is required to access few to single-layer nanosheets. Briefly, the LCO powder is stirred in aqueous HCl of concentrations 0.1, 0.5, 1, 3 M, to replace Li + with H + to varying degrees.…”

Section: Resultsmentioning

confidence: 99%

“…Some layered systems, however, prove more difficult when attempting to isolate their 2D form, due to a strong interlayer coupling based on electrostatic interaction. 12,13 One such layered oxide is LiCoO 2 (LCO), one of the most common cathode materials in lithiumion batteries and the basis of the recent Nobel prize in chemistry. 14−17 Multiple investigations on LiCoO 2 and related compounds suggest that, besides its central role in the operation of rechargeable batteries, this material is extremely rich in complex electronic and magnetic phenomena.…”

Section: Introductionmentioning

confidence: 99%

Electrical Characterization and Charge Transport in Chemically Exfoliated 2D Li_xCoO₂ Nanoflakes

et al. 2020

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Transition metal oxides often possess complex interactions between charge, spin, lattice, and orbital degrees of freedom, resulting in correlated electronic and magnetic phases. Li x CoO2, one of the most commonly used cathode choices in rechargeable batteries, is a prime example of this, evidencing numerous correlated effects evolving as a function of lithium content (x). Due to the strong electrostatic forces that govern the layered nature of this material, however, most investigations of these behaviors have been on bulk forms (>0.1 mm). In the two-dimensional (2D) limit, correlated effects are more easily tuned and studied; therefore, it is of fundamental importance to develop an experimental basis for investigation. Herein, a two-step process is utilized to chemically delithiate and exfoliate LiCoO2 single crystals and study nanoflakes 10–60 nm thick, with 0.37 < x < 0.8. An initial electrical characterization of this new form reflects bulk conduction properties, verifying the reliability of this new technique: temperature-dependent resistance measurements indicate an insulating 2D variable ranging hopping conduction for samples of x > 0.75, and metallic characteristics with a finite residual conductance for x < 0.75. However, these thin flakes also exhibit correlated characteristics less commonly observed and understood in Li x CoO2. An energy barrier upon contact formation is observed for all conditions, independent of lithium concentration and electrode work function, suggesting enhanced correlated effects due to reduced dimensionality. Additionally, charge-ordering phenomena in the temperature-dependent resistance occur under specific preparation conditions. These anomalies are markedly larger in magnitude than previous accounts in bulk systems and are also found in low lithium ranges of x < 0.5, matching theoretical predictions not commonly observed experimentally. This work utilizes a new approach to gain insight behind the complex transport phenomena inherent in Li x CoO2, providing a new opportunity to understand these correlated effects using a 2D, single-crystal form.

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“…electrochemical reductions [ 20 ], nucleation techniques [ 21 ] and other fields of science and technology [ 22 ]. Besides, they also use amorphous Ni materials in many applications such as ceramic additives, capacitive materials, conductive pastes, coatings, lubricants, and electrodes [ 23 , 24 , 25 ]. To study and manufacture amorphous Ni materials, researchers use methods such as experimental methods, theory methods and simulation methods [ 26 ].…”

Section: Introductionmentioning

confidence: 99%

Influence of heating rate, temperature, pressure on the structure, and phase transition of amorphous Ni material: A molecular dynamics study

Minh

Coman

Học

et al. 2020

Heliyon

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The present article is aimed to investigate influence of the heating rate, temperature (T), pressure (P) on the structure and phase transition of amorphous Ni material with heating rate 2 Â 10 5 , 2 Â 10 6 and 2 Â 10 7 K/s at T ¼ 300 K; T ¼ 300, 400, 500, 600, 700, 800, 900 and 1000 K at heating rate 2 Â 10 6 K/s; T ¼ 300, 621 and 900 K at P ¼ 1, 2, 3, 4 and 5 GPa by molecular dynamics simulation method with Sutton-Chen embedded potential and periodic boundary conditions. The structure of amorphous Ni material determined through the radial distribution function, the total energy, the size and the average coordination number. The phase transition and the glass transition temperature determined through the relationship between the total energy and temperature. The result shows that when the heating rate increases, the first peak's position for the radial distribution function is 2.45 Å and a constant, the first peak's height, the total energy and the size increase, the average coordination number decreases from 13 to 12. When temperature increases from 300 to 1000 K at P ¼ 0 GPa, the position decreases from 2.45 Å to 2.40 Å, the average coordination number is 13 and a constant, glass transition temperature is 631 K, the total energy increases, the size increases and happens the phase transition from the amorphous state to the liquid state. When pressure increases from 0 GPa to 5 GPa at T ¼ 300, 621 and 900 K, the position decreases, the height increases, the total energy increases, the size decreases, the average coordination number decreases from 13 to 12, that shows with amorphous Ni material when increasing heating rate, T, P lead to structural change, phase transition of materials is significant.

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Nickel-Doped Sodium Cobaltite 2D Nanomaterials: Synthesis and Electrocatalytic Properties

Cited by 18 publications

References 46 publications

Boron leaching: Creating vacancy-rich Ni for enhanced hydrogen evolution

Boron leaching: Creating vacancy-rich Ni for enhanced hydrogen evolution

Electrical Characterization and Charge Transport in Chemically Exfoliated 2D Li_xCoO₂ Nanoflakes

Influence of heating rate, temperature, pressure on the structure, and phase transition of amorphous Ni material: A molecular dynamics study

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Nickel-Doped Sodium Cobaltite 2D Nanomaterials: Synthesis and Electrocatalytic Properties

Cited by 18 publications

References 46 publications

Boron leaching: Creating vacancy-rich Ni for enhanced hydrogen evolution

Boron leaching: Creating vacancy-rich Ni for enhanced hydrogen evolution

Electrical Characterization and Charge Transport in Chemically Exfoliated 2D LixCoO2 Nanoflakes

Influence of heating rate, temperature, pressure on the structure, and phase transition of amorphous Ni material: A molecular dynamics study

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Electrical Characterization and Charge Transport in Chemically Exfoliated 2D Li_xCoO₂ Nanoflakes