CN111514910A - Co containing cobalt vacancy18Ni2Se20Compound (I) - Google Patents

Abstract

_The invention relates to green energy technology, in particular to a Co ₁₈ Ni ₂ Se _{20 compound} containing cobalt vacancies and _a preparation method. In the present invention, Co _1.8 Ni _0.2 Se ₂ crystals are prepared by solid-phase sintering method, and combined with liquid phase exfoliation, Co ₁₈ Ni ₂ Se ₂₀ compounds containing cobalt vacancies can be obtained, thereby obtaining high electrocatalytic performance. The Co ₁₈ Ni ₂ Se ₂₀ compound containing cobalt vacancies has an overpotential of 185.7 mV and a Tafel slope of ‑62 mV/dec.

Description

A Co18Ni2Se20 Compound Containing Cobalt Vacancies

technical field

The invention relates to electrocatalysis, solid-phase sintering and liquid-phase exfoliation technology, in particular to a preparation method of a Co ₁₈ Ni ₂ Se ₂₀ compound containing cobalt vacancies for electrocatalytic water splitting to produce hydrogen.

technical background

With the development of modern industry, the shortage of energy is becoming more and more serious. Hydrogen production by electrolysis of water is a green technology for hydrogen production, which is safe and environmentally friendly. CoSe compounds have various structures, among which the tetragonal CoSe has high electrocatalytic activity. The generation of Co vacancies by Ni doping can increase the active sites, thereby improving the electrocatalytic performance. Some research works have confirmed that anion vacancies have better active sites, and cation vacancies are less reported. New methods need to be explored to generate cationic vacancies.

SUMMARY OF THE INVENTION

In view of the above problems, the present invention provides a Co ₁₈ Ni ₂ Se ₂₀ compound containing cobalt vacancies with low cost and high efficiency and a preparation method thereof.

In order to achieve the above purpose of the invention, the technical scheme adopted in the present invention is: a Co ₁₈ Ni ₂ Se ₂₀ compound containing cobalt vacancies, and the electrocatalytic water splitting of the Co ₁₈ Ni ₂ Se ₂₀ compound containing cobalt vacancies for hydrogen production. performance, with an overpotential of 185.7mV and a Tafel slope of -62mV/dec.

A method for preparing a Co ₁₈ Ni ₂ Se ₂₀ compound containing cobalt vacancies is characterized in that: comprising the following steps: firstly, cobalt powder, nickel powder and selenium powder are mixed and pressed into ingots in proportion, and potassium ingots weighed in proportion are mixed and pressed into ingots. Put it into a crucible together with the pressed ingot, and seal the crucible in a quartz tube; then put the quartz tube into a muffle furnace and heat it to 1050 °C, keep it for 2 hours, and cool it down to 700 °C at a rate of 5 °C/h , furnace cooling; then put the cooled quartz tube into the glove box to smash and take out the crystals, put the crystals into a 25ml Teflon liner, add 2g cobalt powder, 1g thiourea and 10ml deionized water, put the inner The gallbladder was placed in an autoclave, and the autoclave was heated to 100°C in an oven for 2 days. The crystals in the autoclave were taken out and the cobalt powder on the crystals was washed with deionized water to obtain Co ₁₈ Ni ₂ Se ₂₀ containing cobalt vacancies. crystals; finally, the prepared crystals are put into a hydrothermal kettle containing ethylenediamine to react for 4 hours, and the final product Co ₁₈ Ni ₂ Se ₂₀ compound containing cobalt vacancies is obtained.

The Co ₁₈ Ni ₂ Se ₂₀ compound containing cobalt vacancies in the invention has excellent electrocatalytic performance. The performance of electrocatalytic water splitting for hydrogen production is that the overpotential is 185.7 mV and the Tafel slope is -62 mV/dec.

Description of drawings

FIG. 1 is an XRD pattern of a Co ₁₈ Ni ₂ Se ₂₀ compound containing cobalt vacancies prepared in an embodiment of the present invention.

FIG. 2 is a TEM image of a Co ₁₈ Ni ₂ Se ₂₀ compound containing cobalt vacancies prepared in an embodiment of the present invention.

FIG. 3 is a performance diagram of a Co ₁₈ Ni ₂ Se ₂₀ compound containing cobalt vacancies prepared in an embodiment of the present invention.

Detailed ways

For a better understanding of the present invention, the technical solutions of the present invention will be further described below in conjunction with the accompanying drawings and specific embodiments, referring to FIGS. 1 to 3:

A method for preparing a Co ₁₈ Ni ₂ Se ₂₀ compound containing cobalt vacancies is characterized by comprising the following steps: firstly, cobalt powder, nickel powder and selenium powder are mixed and pressed into ingots according to the proportion, and potassium ingots weighed in proportion are mixed and pressed into ingots. Put it into a crucible together with the pressed ingot, and seal the crucible in a quartz tube; then put the quartz tube into a muffle furnace and heat it to 1050 °C, keep it for 2 hours, and cool it down to 700 °C at a rate of 5 °C/h , furnace cooling; then put the cooled quartz tube into the glove box to smash and take out the crystals, put the crystals into a 25ml Teflon liner, add 2g cobalt powder, 1g thiourea and 10ml deionized water, put the inner The gallbladder was placed in an autoclave, and the autoclave was heated to 100°C in an oven for 2 days. The crystals in the autoclave were taken out and the cobalt powder on the crystals was washed with deionized water to obtain Co ₁₈ Ni ₂ Se ₂₀ containing cobalt vacancies. crystals; finally, the prepared crystals are put into a hydrothermal kettle containing ethylenediamine to react for 4 hours, and the final product Co ₁₈ Ni ₂ Se ₂₀ compound containing cobalt vacancies is obtained.

Co ₁₈ Ni ₂ Se ₂₀ compounds containing cobalt vacancies according to the invention. 1 is an XRD pattern of a Co ₁₈ Ni ₂ Se ₂₀ compound containing cobalt vacancies prepared in an embodiment of the present invention. Compared with the diffraction peaks of an undoped CoSe compound, it can be seen that after Ni doping, the crystal structure type does not change.

FIG. 2 is a TEM image of a Co ₁₈ Ni ₂ Se ₂₀ compound containing cobalt vacancies prepared in an embodiment of the present invention. It can be seen from Fig. 2 that the vacancies in the Co ₁₈ Ni ₂ Se ₂₀ compound contain adjacent cobalt vacancies (shown by open circles).

FIG. 3 is a graph showing the electrocatalytic performance of carbon vacancies prepared in an embodiment of the present invention. It can be seen from Fig. 3 that the Co ₁₈ Ni ₂ Se ₂₀ compound containing cobalt vacancies has an overpotential of 185.7 mV and a Tafel slope of -62 mV/dec.

Claims (3)

1. a preparation method of a Co ₁₈ Ni ₂ Se ₂₀ compound containing cobalt vacancies, is characterized in that: comprising the following steps: first, cobalt powder, nickel powder and selenium powder are mixed and pressed into ingots according to the proportions, and the proportions will be weighed well. The potassium block and the pressed ingot are put into the crucible together, and the crucible is vacuum-sealed in the quartz tube; then the quartz tube is put into the muffle furnace, heated to 1050 °C, kept for 2 hours, and cooled to 5 °C/h. 700 ℃, furnace cooling; then put the cooled quartz tube into the glove box to smash and take out the crystals, put the crystals into a 25ml Teflon liner, add 2g cobalt powder, 1g thiourea and 10ml deionized water, Put the inner tank into an autoclave, heat the autoclave to 100°C in an oven, keep the temperature for 2 days, take out the crystals in the autoclave and wash off the cobalt powder on the crystals with deionized water, to obtain Co ₁₈ Ni ₂ containing cobalt vacancies Se ₂₀ crystals; finally, the prepared crystals are put into a hydrothermal kettle containing ethylenediamine to react for 4 h, and the final product Co ₁₈ Ni ₂ Se ₂₀ compound containing cobalt vacancies is obtained. 2 . The Co ₁₈ Ni ₂ Se ₂₀ compound containing cobalt vacancies prepared by the method according to claim 1 , wherein the vacancies comprise adjacent cobalt vacancies. 3 . 3. the application of the Co ₁₈ Ni ₂ Se ₂₀ compound containing cobalt vacancies prepared by the method according to claim 1 in electrocatalytic water splitting for hydrogen production, wherein the process of the Co ₁₈ Ni ₂ Se ₂₀ compound containing cobalt vacancies The potential was 185.7mV and the Tafel slope was -62mV/dec.

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