CN111876748B

CN111876748B - Metal sulfide thin film based on organic sulfur precursor and preparation method thereof

Info

Publication number: CN111876748B
Application number: CN202010686717.1A
Authority: CN
Inventors: 王新炜; 李豪
Original assignee: Peking University Shenzhen Graduate School
Current assignee: Peking University Shenzhen Graduate School
Priority date: 2020-07-16
Filing date: 2020-07-16
Publication date: 2022-07-29
Anticipated expiration: 2040-07-16
Also published as: CN111876748A

Abstract

The invention provides a metal sulfide film based on an organic sulfur precursor and a preparation method thereof. The preparation method of the invention adopts the organic sulfur compound to replace highly toxic H ₂ The S gas is used as a sulfur source precursor, potential safety hazards of harmful gases to the film preparation process are reduced, the method is environment-friendly, and the metal sulfide film prepared by the method is compact, uniform, good in crystallinity and excellent in electrocatalysis performance, and can be applied to the field of electrocatalysis.

Description

Metal sulfide thin film based on organic sulfur precursor and preparation method thereof

Technical Field

The invention relates to the technical field of metal sulfide thin film preparation, in particular to a metal sulfide thin film based on an organic sulfur precursor and a preparation method thereof.

Background

The metal sulfide thin film has excellent electrical, optical, magnetic and electrochemical properties, thereby drawing wide attention of researchers in various fields, and showing great application potential in the fields of integrated circuits, gas sensors, photoelectric detectors, solar cells, electrochemical catalysis and the like. The traditional method for synthesizing the metal sulfide thin film mainly comprises electrodeposition, chemical water bath deposition, chemical vapor deposition, physical vapor deposition and the like. In recent years, the Atomic Layer Deposition (ALD) technology has evolved into an important high-quality metal sulfide thin film preparation method, and the ALD technology can grow a uniform, continuous, high-quality thin film with precisely controllable thickness on various substrates including some complex nanostructures. Over the past decade, ALD of new metal sulfides has progressed very rapidly, including GaS _x ，GeS，CdS，MoS ₂ ，Li ₂ S，CoS _x ，NiS _x ，MnS，FeS _x ，VS4，ReS ₂ ，HfS ₂ ，ZrS ₂ And the like, can be realized by the ALD technique. However, the sulfur source precursors used to prepare these metal sulfides using ALD are essentially all H ₂ S gas, and H ₂ S gas as oneThe high-toxicity, inflammable and corrosive gas has great potential safety hazard in the processes of storage, transportation, use and the like. Is provided with H ₂ The S cylinders need to be stored in a professional storage cabinet and provided with a professional H ₂ S gas sensor using H ₂ Strict operation steps need to be observed in the S process, and the problems greatly hinder the development and development of the method of ALD new metal sulfide.

Accordingly, the prior art is yet to be improved and developed.

Disclosure of Invention

In view of the above-mentioned shortcomings of the prior art, the present invention provides a metal sulfide thin film based on an organosulfur precursor and a method for preparing the same, which is intended to improve the safety of the metal sulfide thin film preparation process.

The technical scheme of the invention is as follows:

a method for preparing a metal sulfide thin film based on an organosulfur precursor, comprising the steps of:

A. placing the pretreated substrate in an atomic layer deposition reaction chamber;

B. introducing a metal precursor heated to a first temperature into the deposition reaction chamber under inert gas to enable the metal precursor to react with the substrate, and generating a metal monoatomic layer on the surface of the substrate;

C. introducing an organic sulfur precursor heated to a second temperature into the deposition reaction chamber, so that the organic sulfur precursor reacts with the metal monoatomic layer, and a metal sulfide monomolecular layer is generated on the surface of the substrate;

D. Repeating the steps B to C for a plurality of times until the metal sulfide thin film with the preset thickness is obtained.

The preparation method, wherein the step B specifically includes:

introducing a metal precursor heated to 20-200 ℃ into the deposition reaction chamber under inert gas to enable the metal precursor to react with the substrate;

and after the reaction is finished, introducing inert gas to purge redundant metal precursors and reaction byproducts, and generating a metal monoatomic layer on the surface of the substrate.

The preparation method, wherein the step C specifically includes:

introducing an organic sulfur precursor heated to 20-200 ℃ into the deposition reaction chamber, so that the organic sulfur precursor reacts with the metal monoatomic layer;

and after the reaction is finished, introducing inert gas to purge redundant organic sulfur precursors and reaction byproducts, and generating a metal sulfide monomolecular layer on the surface of the substrate.

The metal in the metal precursor includes one of nickel, copper, cobalt, iron, manganese, tungsten, rhenium, indium, tin, lead, bismuth, hafnium, zirconium, titanium, chromium, cadmium, tantalum, vanadium and germanium.

The preparation method, wherein the organic sulfur precursor comprises one or more of tert-butyl disulfide, diisopropyl disulfide, diallyl disulfide, dimethyl disulfide, diethyl disulfide, di-n-propyl disulfide, diisobutyl disulfide, di-n-butyl disulfide, dibenzyl disulfide, allylpropyl disulfide, diphenyl disulfide, dimethyl sulfide, diethyl sulfide, methyl ethyl sulfide, dipropyl sulfide, dibutyl sulfide, allylmethyl sulfide, allylethyl sulfide, diallyl sulfide, dibenzyl sulfide and diphenyl sulfide.

The preparation method comprises the step of repeating the steps B to C once, wherein the exposure dose of the metal precursor is 0.001-20 Torr & s, and the exposure dose of the organic sulfur precursor is 0.01-20 Torr & s.

The preparation method is characterized in that the reaction temperature is 50-500 ℃.

The metal sulfide thin film based on the organic sulfur precursor is prepared by the preparation method of the metal sulfide thin film based on the organic sulfur precursor.

A metal sulfide catalytic electrode comprising a substrate and a metal sulfide thin film disposed on the substrate, wherein the metal sulfide thin film is the metal sulfide thin film based on an organosulfur precursor as described above.

The metal sulfide catalytic electrode is characterized in that the substrate is a carbon cloth with carbon nano tubes distributed on the surface.

Has the advantages that: according to the method, a metal precursor is introduced into an atomic layer deposition reaction chamber in the presence of inert carrier gas by adopting an atomic layer deposition technology, so that the metal precursor reacts with the surface of a substrate in the atomic layer deposition reaction chamber to obtain a metal atomic layer, and an organic sulfur precursor is introduced into the atomic layer deposition reaction chamber in a pulse mode to react the organic sulfur precursor with the metal atomic layer to obtain the metal sulfide film based on the organic sulfur precursor. The preparation method of the invention adopts the organic sulfur compound to replace highly toxic H ₂ The S gas is used as a sulfur source precursor, potential safety hazards of harmful gases to the film preparation process are reduced, the method is environment-friendly, and the metal sulfide film prepared by the method is compact, uniform, good in crystallinity and excellent in electrocatalysis performance, and can be applied to the field of electrocatalysis.

Drawings

FIG. 1 (a-d) preparation of NiS Using TBDS, IPDS, DMDS or DADS as organosulfur precursors _x Growth characteristics of the film. Wherein (a) is Ni (amd) ₂ Exposure dose versus film thickness; (b) the relationship between TBDS, IPDS, DMDS or DADS exposure dose and film thickness; (c) film thickness versus ALD cycle number; (d) the growth rate is a function of the reaction temperature. The growth conditions in (c-d) are all the film saturation growth conditions in the curve (a-b) (Ni (amd)) ₂ The saturation exposure dose of (2) is 0.12Torr · s, and the saturation exposure dose of the organic sulfur precursor is 0.2Torr · s).

FIGS. 2 (a-c) are the preparation of NiS at 200 ℃ with TBDS as the organosulfur precursor _x TEM images of the thin film and its corresponding electron diffraction ring. Wherein (a) is a TEM image; (b) is an electron diffraction ring image; (c) is a result graph of fast Fourier transform in the square region selected from (a).

FIGS. 3 (a-f) are the preparation of NiS at 200 ℃ with IPDS, DMDS, DADS as organosulfur precursors, respectively _x TEM images of the thin film and its corresponding electron diffraction ring. Wherein, (a), (b) and (c) respectively use IPDS, DMDS and DADS as organic sulfur precursors to prepare NiS _x TEM images of the thin film, and (d), (e) and (f) are electron diffraction ring images corresponding to (a), (b) and (c), respectively.

FIG. 4 is NiS prepared at 200 ℃ with TBDS as organosulfur precursor _x The atomic number ratio of Ni and S elements in the film is plotted against the deposition temperature.

FIGS. 5 (a-e) NiS with TBDS deposited as organosulfur precursor _x SEM images of the film at different reaction temperatures, wherein (a) is 180 ℃; (b) is 200 ℃; (c) is 220 ℃; (d) is 235 ℃; (e) the temperature was 250 ℃.

FIG. 6 NiS deposited with TBDS as the organosulfur precursor _x Film surface roughness of the film as a function of deposition temperature.

FIGS. 7(a-c) are NiS deposited with IPDS, DMDS, DADS as organosulfur precursors at 200 deg.C _x SEM image of the film. Wherein (a), (b) and (c) respectively use IPDS, DMDS and DADS as organic sulfur precursors.

FIG. 8 shows NiS prepared with TBDS as the organosulfur precursor _x XPS full element spectra of films.

FIGS. 9 (a-d) is NiS prepared with TBDS as the organosulfur precursor _x XPS narrow-band spectra of the films. Wherein (a), (b), (C) and (d) are high-resolution XPS narrow-band spectra of Ni 2p, S2 p, C1S and N1S respectively.

FIGS. 10(a, b) are NiS prepared with IPDS, DMDS, DADS as sulfur precursors, respectively _x Thin film XPS spectra. Wherein (a) and (b) are high resolution XPS narrow band spectra of C1s and N1s, respectively

FIG. 11(a, b) shows an electrode NiS _x SEM image and energy spectrum distribution diagram of/CNT/CC surface, wherein (a) is NiS _x The macro structure of the surface of/CNT/CC, and (b) is NiS _x Morphology of film coated CNT/CC, FIG. 12 is an electrode NiS _x Full-element energy spectrum distribution diagram of/CNT/CC surface

FIG. 13 (a-d) shows an electrode NiS _x TEM image and single element spectral profile of/CNT/CC surface, whereinAnd (a) is NiS _x TEM image of/CNT/CC, and (b-d) are spectra distribution diagrams of Ni, S and C elements, respectively.

FIG. 14 shows NiS _x /CNT/CC、NiS _x (iv) GC and RuO ₂ LSV test profile of/GC.

FIG. 15 shows NiS _x (CNT)/CC and NiS _x Tafel plot of/GC.

FIG. 16 shows NiS _x The current density of the/CNT/CC is 10mA cm respectively ^-2 And 20mA cm ^-2 Stability test graph below.

FIGS. 17 (a-b) are graphs showing 10, 20, 40, 80, and 160mV s in the vicinity of the open circuit voltage ^-1 Is measured at a scanning speed, wherein (a) is NiS _x CV curve of/CNT/CC, (b) is NiS _x CV curve of/GC.

FIG. 18 shows NiS _x (CNT)/CC and NiS _x The current density of the/GC is plotted against the scanning speed, wherein the slope is the size of the double electric layer capacitor.

FIG. 19 is normalized NiS _x CNT/CC and NiS _x LSV plot of/GC.

Detailed Description

The present invention provides a metal sulfide thin film based on an organosulfur precursor and a method for preparing the same, and the present invention will be described in further detail below in order to make the objects, technical solutions, and effects of the present invention clearer and clearer. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

The invention provides a preparation method of a metal sulfide film based on an organic sulfur precursor, which comprises the following steps:

s10, placing the pretreated substrate in an atomic layer deposition reaction chamber;

s20, introducing a metal precursor heated to a first temperature into the deposition reaction chamber under inert gas to enable the metal precursor to react with the substrate, and generating a metal monoatomic layer on the surface of the substrate;

s30, introducing the organic sulfur precursor heated to the second temperature into the deposition reaction chamber, so that the organic sulfur precursor reacts with the metal monoatomic layer to generate a metal sulfide monomolecular layer on the surface of the substrate;

And S40, repeating the steps 20 to 30 for a plurality of times until the metal sulfide thin film with the preset thickness is obtained.

Specifically, an ALD technology is adopted, after a deposition substrate is placed in an ALD reaction chamber, a metal precursor is heated to form steam, the metal precursor steam is conveyed into the ALD reaction chamber under the assistance of high-purity inert gas, the metal precursor reacts with the substrate at a certain temperature, and a layer of metal monoatomic layer is deposited on the substrate; and then, introducing an organic sulfur precursor in a pulse mode, reacting the organic sulfur precursor with the metal monoatomic layer at a certain temperature to form a metal sulfide monomolecular layer, and depositing a plurality of metal sulfide monomolecular layers on the substrate by using the step S20 and the step S30 as an ALD period through a cycle of the ALD period to obtain the metal sulfide thin film with the required thickness.

This embodiment is directed to the existing adoption of H ₂ S is used as a sulfur precursor of ALD to prepare a metal sulfide thin film, so that the metal sulfide thin film has a great safety problem, and an organic sulfur compound is used as the sulfur precursor to replace highly toxic H ₂ And (4) S gas. The organic sulfur precursor is convenient to store, and the organic sulfur precursor is not required to be introduced in a strict and standard operation mode in the ALD process, so that the fussy operation steps are reduced, the safety risk in the preparation process of the metal sulfide film is reduced, and the preparation method of the metal sulfide film is environment-friendly. Meanwhile, the prepared metal sulfide thin film is compact, uniform, good in crystallinity and excellent in electrocatalysis performance.

Further, the step S20 specifically includes:

s21, introducing a metal precursor heated to 20-200 ℃ into the deposition reaction chamber under inert gas to enable the metal precursor to react with the substrate;

and S22, introducing inert gas to purge redundant metal precursors and reaction byproducts after the reaction is finished, and generating a metal monoatomic layer on the surface of the substrate.

Specifically, the metal precursor and the organic sulfur precursor are required to form metal precursor vapor and organic sulfur precursor vapor at a certain temperature, and then the metal precursor vapor and the organic sulfur precursor vapor are respectively introduced into the ALD reaction chamber for reaction. Heating the metal precursor to the temperature of 20-200 ℃ to form metal precursor steam, introducing the metal precursor steam into the deposition reaction chamber with the aid of high-purity inert gas, and introducing inert gas to purge unreacted metal precursor and by-products generated after the metal precursor reacts, so as to form a metal monoatomic layer on the substrate.

Further, the step S30 specifically includes:

s31, introducing an organic sulfur precursor heated to 20-200 ℃ into the deposition reaction chamber, and reacting the organic sulfur precursor with the metal monoatomic layer;

And S32, introducing inert gas to purge redundant organic sulfur precursors and reaction byproducts after the reaction is finished, and generating a metal sulfide monomolecular layer on the surface of the substrate.

Specifically, in the organic sulfur precursor, whether heating is needed or not is determined according to the volatility of the organic sulfur precursor, if the organic sulfur precursor with better volatility is adopted, the organic sulfur precursor can be introduced into the ALD reaction chamber without heating the organic sulfur precursor, and if the organic sulfur precursor with poorer volatility at room temperature is adopted, the organic sulfur precursor is heated and then introduced into the ALD reaction chamber. And introducing organic sulfur precursor steam into the ALD reaction chamber, and introducing inert gas to purge the unreacted organic sulfur precursor and the byproduct generated after the organic sulfur precursor reacts, so as to form a metal sulfide monomolecular layer on the substrate.

Further, in steps S22 and S32, the inert gas is purged for 30 to 60 seconds while maintaining the pressure in the ALD reaction chamber at 0.01 to 5Torr during the purging. The inert gas can adopt one or a mixture of nitrogen, argon and helium.

Further, the substrate can be made of silicon chips, glassy carbon and carbon cloth, and the pretreatment method comprises the step of irradiating the substrate for 5-10 min by using an ultraviolet lamp to remove impurities adsorbed on the surface of the substrate.

In one embodiment, the metal in the metal precursor may be, but is not limited to, one of nickel, copper, cobalt, iron, manganese, tungsten, rhenium, indium, tin, lead, bismuth, hafnium, zirconium, titanium, chromium, cadmium, tantalum, vanadium, and germanium. According to different metal precursors, different metal sulfide thin films can be prepared, for example, thin films such as copper sulfide, cobalt sulfide, iron sulfide, manganese sulfide, tin sulfide and the like can be prepared. As the metal precursor, an organic metal compound material can be used, and as an example of the metal nickel precursor, one or more of bis (nitrogen, nitrogen-di-t-butylpropanimidamidyl) nickel, bis (nitrogen, nitrogen-diisopropylacetamidinato) nickel, nickel diacetoacetonate, bis (alkyl-cyclopentadienyl) nickel, and bis (2,2,6, 6-tetramethyl-3, 5-heptanedionato) nickel can be used.

In one embodiment, the organosulfur precursor includes one or more of t-butyl disulfide, diisopropyl disulfide, diallyl disulfide, dimethyl disulfide, diethyl disulfide, dipropyl disulfide, diisobutyl disulfide, di-n-butyl disulfide, dibenzyl disulfide, allylpropyl disulfide, diphenyl disulfide, dimethyl sulfide, diethyl sulfide, methyl ethyl sulfide, dipropyl sulfide, dibutyl sulfide, allyl methyl sulfide, allyl ethyl sulfide, diallyl sulfide, dibenzyl sulfide, and diphenyl sulfide.

In one embodiment, the exposing dose of the metal precursor is 0.001 to 20Torr S and the exposing dose of the organic sulfur precursor is 0.01 to 20Torr S, every time the steps S20 to S30 are repeated. If the exposure dose of the metal precursor or the organic sulfur precursor is too small, the metal sulfide thin film does not grow, and if the exposure dose of the metal precursor or the organic sulfur precursor is too large, the metal precursor or the organic sulfur precursor is wasted. Preferably, the exposure dose of the metal precursor is 0.02-0.25, which is the minimum exposure dose of the metal precursor; the exposure dose of the organic sulfur precursor is 0.05-0.35, and the specific optimal exposure dose needs to be selected according to the organic sulfur precursor, for example, the exposure dose of the organic sulfur precursor using TBDS is 0.15Torr · s (minimum exposure dose); the exposure dose with IPDS was 0.08Torr · s (minimum exposure dose); the exposure dose with DADS was 0.2Torr · s (minimum exposure dose); the exposure dose using DMDS was 0.17Torr s (minimum exposure dose).

In one embodiment, the reaction temperature is 50 to 500 ℃. The reaction temperature is the deposition temperature of the metal precursor and the organic sulfur precursor for depositing the film on the substrate, the reaction temperature has great influence on the growth of the metal sulfide film, and the reaction temperature is lower than 50 ℃, so that the metal precursor and the organic sulfur precursor do not react, and the metal sulfide film does not grow; and as the temperature increases, the film growth rate increases with the increase of the deposition temperature; when the temperature is higher than 500 ℃, part of the metal precursor can be decomposed by itself, so that chemical vapor deposition components are introduced in the growth process of the film, the impurities of the film are increased, and the film forming performance is influenced.

The invention also provides a metal sulfide film based on the organic sulfur precursor, which is prepared by the preparation method of the metal sulfide film based on the organic sulfur precursor.

The invention also provides a catalytic electrode, which comprises a substrate and the metal sulfide thin film arranged on the substrate, wherein the metal sulfide thin film adopts the metal sulfide thin film based on the organic sulfur precursor.

In one embodiment, the substrate is a carbon cloth with carbon nanotubes distributed on the surface. The carbon cloth is rough and porous in surface and large in surface area, the carbon nano tubes are coated on the surface of the carbon cloth, and the metal sulfide thin film is deposited on the surface of the carbon cloth by adopting an ALD (atomic layer deposition) method, so that the number of catalytic active sites of the electrode can be increased, and the electrode has better electrocatalysis performance.

The metal sulfide thin film based on an organosulfur precursor and a method for preparing the same according to the present invention are described below by way of specific examples:

example 1

1. Nickel sulfide (NiS) based on organosulfur precursors _x ) And (3) preparing a film.

Will be passedThe pretreated substrate was placed in an ALD reactor, the temperature in the reactor was controlled to 200 ℃ and bis (nitrogen, nitrogen-di-t-butylacetamidyl) nickel (Ni (amd) ₂ ) Heating to 70 deg.C to form bis (N, N-di-tert-butylacetamidyl) nickel vapor in high purity N ₂ 0.12Torr s of bis (N, N-di-tert-butylacetamidyl) nickel vapor was passed into the ALD chamber with the aid of a carrier gas, and N was then passed into the ALD chamber ₂ The first purge was performed for 30 seconds to remove unreacted bis (N, N-di-tert-butylacetamidyl) nickel precursor and reaction byproducts, followed by heating the tert-butyldisulfide (TBDS) precursor to 35 deg.C, filling the gas trap with the resulting TBDS vapor, and pulsing the ALD reactor with TBDS vapor in a 0.15Torr s gas trap. Then introducing N into the ALD reaction chamber ₂ And purging for a second time for 30 seconds to remove unreacted TBDS precursor and reaction byproducts. By introduction of nickel precursor and first N ₂ Purging, introduction of organic sulfur precursor and second N ₂ Purge as one ALD cycle, control of NiS _x The number of ALD cycles for the thin film was 300, yielding a desired thickness of TBDS-based NiS _x Film, NiS obtained in this example _x The chemical formula of the film is Ni ₉ S ₈ 。

The organic sulfur precursor is changed into respectively diisopropyl disulfide (IPDS), diallyl disulfide (DADS) and dimethyl disulfide (DMDS), and NiS based on IPDS is prepared according to the steps _x Thin film, DADS-based NiS _x Thin films and DMDS-based NiS _x Thin film, wherein the difference is that DMDS does not require heating prior to introduction into the ALD reaction chamber.

2. NiS based on organosulfur precursors _x And (5) characterization of the thin film.

It is noted that unless otherwise indicated, the following characterizations and tested NiS _x The experimental parameters of the films were the same as those in step 1.

(1) Investigation of NiS _x Growth characteristics of the thin film.

By varying the Ni precursor (Ni (amd)) ₂ Exposure dose of nickel precursor, exposure dose of organosulfur precursor TBDS, IPDS, DMDS or DADS, ALD cycle number andreaction temperature to examine ALD parameters vs. NiS _x Influence of growth condition of the thin film. As shown in FIGS. 1 (a-d), while keeping the other experimental parameters unchanged, NiS was studied by sequentially changing the above parameters _x Growth characteristics of thin films that conform to ideal ALD self-limiting and saturation deposition characteristics. As can be seen from FIG. 1(a), while maintaining the exposure dose of TBDS, IPDS, DMDS or DADS at about 0.2Torr s, Ni (amd) is gradually increased ₂ The film thickness shows a trend of gradually increasing initially and finally reaching a saturation state, wherein the saturation state corresponds to Ni (amd) ₂ The exposure dose of (A) was 0.12Torr · s. As shown in FIG. 1(b), Ni (amd) is retained ₂ Under the condition that the exposure dose of (2) is 0.12Torr s, the exposure dose of TBDS, IPDS, DADS or DMDS, NiS, is gradually increased _x The film thickness also shows a tendency to increase gradually initially and finally to reach a saturation state. Wherein when the organosulfur precursors are respectively: when the exposure dose of TBDS is greater than 0.15Torr s, the exposure dose of IPDS is greater than 0.08Torr s, or the exposure dose of DADS is greater than 0.2Torr s, the minimum exposure dose of each organic sulfur precursor is reached and the film thickness is not substantially changed when the exposure dose of DMDS is greater than 0.17Torr s. As shown in FIG. 1(c), NiS _x The film thickness and the ALD cycle number follow a very good linear relationship, which shows that the film thickness can be accurately controlled by changing the ALD cycle number, the slope of a fitted line is the growth rate of the film, and the intercept of the fitted line is about 1-2nm, which indicates that the growth rate of the film is faster in the initial stage, and then the growth rate is kept constant. As can be seen from FIG. 1(d), NiS _x The film grows slowly under the condition that the reaction temperature is lower than 180 ℃, when the reaction temperature is higher than 180 ℃, the film growth rate is increased along with the increase of the reaction temperature, and when the reaction temperature is higher than 250 ℃, the film growth rate is obviously increased, but the film growth rate is probably caused by Ni (amd) ₂ Partial decomposition of the precursor, thereby introducing chemical vapor deposition constituents into the film during growth.

(2) TEM (Transmission Electron microscope, Jeol, JEM-2100) was used to align the NiS _x The film was subjected to microstructural characterization.

Preparation of NiS at 200 ℃ with TBDS as organic sulfur precursor _x TEM images of the thin film and its corresponding electron diffraction rings are shown in FIGS. 2 (a-c), in which NiS _x The film thickness was about 10 nm. As can be seen from FIG. 2(a), NiS _x The film has good crystallinity, the grain size is about 10nm, and NiS can be seen from figure 2(b) _x The films are all polycrystalline structures, and NiS can be known through measuring and comparing the radius values of the diffraction rings _x The crystal structure of the film belongs to orthorhombic system and has the chemical formula of Ni ₉ S ₈ (

PDF #22-1193), FIG. 2(c) is a graph of the result of fast Fourier transform within the square region selected from FIG. 2(a), and it can be seen that all diffraction points can be associated with orthorhombic Ni ₉ S ₈ Crystal face indexes in the structure correspond to each other, and the analysis result of a diffraction ring is further verified, namely NiS prepared by adopting TBDS _x Film of Ni belonging to orthorhombic system ₉ S ₈ 。

Respectively taking IPDS, DMDS and DADS as organic sulfur precursors to prepare NiS at 200 DEG C _x TEM images of the thin films and their corresponding electron diffraction rings are shown in FIGS. 3 (a-f), and from FIGS. 3 (a-c), it can be seen that NiS was produced from these sulfur precursors _x The thin film exhibits some crystallinity. The electron diffraction patterns of FIGS. 3 (d-f) show that these nickel sulfide films are all polycrystalline, with NiS prepared using IPDS, DMDS _x The crystal structure of the thin film is consistent with that of the Ni adopting TBDS and having orthorhombic structure ₉ S ₈ (

PDF #22-1193), and the nickel sulfide thin film prepared using DADS as a precursor belongs to the hexagonal system, whose chemical formula is NiS (PDF # 02-1280).

(3) NiS pairs with XRF (X-ray fluorescence, Rigaku, ZSX Primus II) _x And (4) carrying out atomic mass ratio characterization on the film.

NiS prepared by taking TBDS as organic sulfur precursor _x The relationship between the atomic number ratio of Ni and S elements in the thin film and the deposition temperature is shown in FIG. 4, and it can be seen that the atomic number ratio (x) of Ni and S is maintained in the range of 1.08 to 1.25 in the temperature range of 180 to 250 deg.C, which is in turn associated with Ni ₉ S ₈ Also, the atomic ratio of Ni to S of 1.125 was satisfied.

(4) NiS was aligned using SEM (scanning Electron microscope, Zeiss, SUPRA55) and AFM (atomic force microscope, Bruker, MultiMode 8) _x And (5) characterizing the surface appearance and roughness of the film.

Preparation of NiS with TBDS as organic sulfur precursor _x SEM images of the films at temperatures of 180, 200, 220, 235 and 250 ℃ are shown in FIGS. 5 (a-e), and it can be seen from FIGS. 5 (a-e) that NiS grows at 180-220 ℃ _x The film is continuous and the surface is smooth and flat, and NiS grows at 250 DEG C _x The grain size of the film is obviously coarse and the surface is rough. FIG. 6 is a graph of the surface roughness value of a thin film obtained by AFM as a function of deposition temperature, and it is understood that the roughness of the surface of the thin film gradually increases with the increase of reaction temperature, and NiS prepared at 200 ℃ is obtained _x The film surface roughness was 2.8nm (film thickness about 16nm) and the surface roughness at 250 ℃ was up to about 5.7 nm. FIGS. 7 (a-c) are NiS prepared at 200 ℃ using IPDS, DMDS, DADS as organosulfur precursors, respectively _x SEM images of the films show that the films prepared by IPDS, DMDS and DADS are all relatively compact and uniform in the whole, and compared with DADS, the nickel sulfide films obtained by IPDS and DMDS are smaller in grain size and smoother in surface.

(4) NiS was treated with XPS (Thermo Scientific, Escalab 250Xi) _x The film was subjected to elemental characterization.

Before XPS spectra were collected, Ar was first used ⁺ Sputtering was carried out at 3keV for 10s to remove carbon contamination from the sample surface. NiS prepared by taking TBDS as sulfur precursor _x XPS spectra of the films are shown in FIGS. 8 and 9 (a-d), and it can be seen from FIG. 8 that NiS is deposited at 200 deg.C _x The film is very pure and does not appear C. The peak positions of impurity elements such as N contain characteristic peak position signals of Ni and S elements. In FIG. 9(a), the Ni 2p map is at 852.7eV (2 p) _3/2 ) And 869.9eV (2 p) _1/2 ) Two spin-splitting orbital peaks appear at the position; in FIG. 9(b), XPS S2 p spectra were at 161.5eV (2 p) _3/2 ) And 162.5eV (2 p) _1/2 ) Two spin-orbit cleavage peaks appear at the position, and the peak positions and peak shapes of all Ni 2p and S2 p are the same as those of NiS reported by the literature _x Are kept consistent. As can be seen from FIGS. 9(C) and 9(d), the thin films prepared using TBDS had very weak signal intensities in XPS C1s and N1s, and the quantitative results showed that the C content was only about 1.3%, while the N content was even below the XPS detection line, indicating that NiS grown using TBDS as a sulfur precursor _x The film is very pure. NiS prepared by respectively adopting IPDS, DMDS and DADS as sulfur precursors _x The C1s and N1s patterns of the film are shown in FIG. 10(a, b), and it can be seen that NiS prepared using IPDS _x The C and N impurity content in the film is also very low, while NiS prepared with DMDS _x The film contains 5.7% of C element and 1.7% of N element, and NiS prepared by DADS _x The film contained 8.0% of C element and 2.8% of N element.

Example 2

1. Nickel sulfide (NiS) based on organosulfur precursors _x ) Thin film carbon cloth based catalytic electrode (NiS) _x /CNT/CC).

A carbon nanotube/carbon cloth (CNT/CC) substrate is fabricated by drop coating a Carbon Nanotube (CNT) suspension onto a Carbon Cloth (CC). Deposition of NiS on CNT/CC with TBDS as organosulfur precursor _x Thin films deposited in the same manner and with the same parameters as in example 1, except that the number of ALD cycles was 500, and the resulting oxygen evolution reaction electrode was designated NiS _x /CNT/CC. For comparison, NiS was also deposited using the same deposition parameters _x The film is deposited on a pretreated flat glassy carbon electrode, the resulting oxygen evolution reaction electrode being denoted as NiS _x (ii) GC, and use of RuO ₂ The suspension was drop coated onto a pretreated glassy carbon electrode to produce a standard catalyst electrode designated as RuO ₂ /GC。

2、NiS _x Characterization of the/CNT/CC catalytic electrode.

(1)NiS _x Surface morphology and composition characterization of/CNT/CC.

NiS _x SEM images of/CNT/CC are shown in FIG. 11(a, b), and NiS can be seen from FIG. 11(a) _x The surface of the/CNT/CC is rough and porous. From FIG. 11(b), it can be seen that CNT/CC is coated with ALD NiS _x The surface appearance behind the film, CNT/CC network structure obviously thickens. NiS _x The energy spectrum distribution of/CNT/CC is shown in FIG. 12, and NiS can be seen _x The existence of Ni and S elements on the surface of the/CNT/CC proves that the surface layer of the CNT/CC structure is NiS _x A film.

NiS _x The TEM image and the elemental spectrum distribution of the/CNT/CC surface are shown in FIGS. 13 (a-d), and NiS is shown in FIG. 13(a) _x Uniformly coated around the CNT with a thickness of 8nm, the corresponding elementary spectra profile 13 (b-c) further demonstrates that NiS _x The Ni element and the S element in the thin film are uniformly distributed on the CNT/CC.

(2)NiS _x OER (oxygen evolution) performance characterization of/CNT/CC.

A standard three-electrode system is adopted, wherein Hg/HgO is used as a reference electrode, a Pt wire is used as a counter electrode, and a working electrode is NiS _x CNT/CC, electrolyte 0.1mol L ^-1 KOH solution of (a). The conversion relation between the standard hydrogen reversible electrode potential (RHE) and the test voltage is as follows:

E _RHE ＝E _Hg/HgO +0.0591×pH+0.098(V)。

all the electric potentials are subjected to internal resistance deduction treatment, wherein the internal resistance value is obtained by using a current perturbation method. The conversion relation between the OER overpotential eta and the RHE potential is as follows:

η＝E _RHE –1.229(V)。

FIG. 14 shows NiS _x /CNT/CC、NiS _x (iv) GC and RuO ₂ LSV (Linear sweep voltammetry) test plot for/GC, it can be seen that NiS _x the/CNT/CC has very good catalytic activity, and the current density reaches 10mA cm under the overpotential of 221mV ^-2 (dotted line position), and NiS _x (iv) GC and RuO ₂ the/GC needs to apply overpotential of 303mV and 409mV respectivelyCan reach 10mA cm ^-2 . The catalytic activity is also better compared to other oxygen evolution electrocatalysts of Ni-based systems.

FIG. 15 shows NiS _x /CNT/CC、NiS _x The Tafel (Tafel) curve of the film has the Tafel slope which can reflect the speed of the dynamic process of the catalyst in the catalytic reaction process. As can be seen from FIG. 15, NiS _x CNT/CC and NiS _x Tafel slopes of/GC are the same and are relatively small, and are only 48mV/decade, further showing that NiS _x the/GC is an excellent oxygen evolution electrocatalyst and can rapidly and efficiently catalyze the oxygen evolution process. And NiS at the same potential _x The large current density of the/CNT/CC is due to its surface area compared to NiS _x The surface area of the/GC is larger, the number of active sites is more, and the catalyst has better catalytic performance.

FIG. 16 shows NiS _x The current density of the/CNT/CC is 10mA cm respectively ^-2 And 20mA cm ^-2 Stability test curve under the conditions, it can be seen that NiS _x The overpotential required for the/CNT/CC test remained essentially unchanged over a test period of 40 hours, indicating that NiS _x the/CNT/CC can stably perform catalytic oxygen evolution for a long period of time.

For quantitative analysis of NiS _x The electrochemical active area of the/CNT/CC was further tested for its CV curve at different scanning speeds in the range around the open circuit voltage, as shown in FIGS. 17 (a-b), and it can be seen that NiS _x The current density of/CNT/CC is far larger than that of NiS _x and/GC. FIG. 18 shows NiS _x /CNT/CC and ALD NiS _x The curve of the relationship between the current density of the film and the scanning speed is the slope of the curve, namely the size of the electric double layer capacitor corresponding to the catalytic electrode, wherein NiS _x capacitance/GC of 0.23 mF-cm ^-2 ，NiS _x The capacitance of/CNT/CC is NiS _x 60.4 times of/GC, 13.90 mF-cm ^-2 Indicating NiS _x the/CNT/CC has much more electrochemical active area, and NiS is deposited on the CNT/CC due to the larger surface area of the substrate CNT/CC _x The catalytic electrode formed by the film can expose more catalytic active sites in the electrocatalysis process, so that NiS can be obtained at the same potential _x the/CNT/CC shows better OER catalytic performance. FIG. 19 comparisonAfter standardization of the active area, NiS _x (CNT)/CC and NiS _x (GC) (NiS in FIG. 14) _x LSV curve of/GC multiplied by 60.4 times). It can be seen that the two curves are substantially completely coincident, demonstrating NiS _x The effective catalytic layer of the/CNT/CC is all from NiS with the surface of the CNT/CC being uniformly coated _x A film.

For NiS _x OER performance characterization results of/CNT/CC show that NiS _x the/CNT/CC has excellent electrocatalytic performance, and the main reason is that the ALD technology can lead the OER active material NiS _x Uniformly coated on the CNT/CC substrate, and by fully utilizing the characteristic of large surface area of the CNT/CC, more active sites are exposed in the electrochemical process, so that the OER process is catalyzed more effectively.

In summary, the metal sulfide thin film based on the organic sulfur precursor is obtained by introducing the metal precursor into the atomic layer deposition reaction chamber in the presence of the inert carrier gas by adopting the atomic layer deposition technology to deposit a metal monoatomic layer, and then introducing the organic sulfur precursor into the atomic layer deposition reaction chamber in a pulse mode to obtain a metal sulfide molecular layer, wherein the process of forming the molecular layer is an ALD period, and the metal sulfide thin film based on the organic sulfur precursor is obtained by cycling the ALD period. The preparation method of the invention adopts the organic sulfur compound to replace highly toxic H ₂ The S gas is used as a sulfur source precursor, potential safety hazards of harmful gases to the film preparation process are reduced, the method is environment-friendly, and the metal sulfide film prepared by the method is compact, uniform, good in crystallinity and excellent in electrocatalysis performance, and can be applied to the field of electrocatalysis.

It is to be understood that the invention is not limited to the examples described above, but that modifications and variations may be effected thereto by those of ordinary skill in the art in light of the foregoing description, and that all such modifications and variations are intended to be within the scope of the invention as defined by the appended claims.

Claims

1. A method for preparing a metal sulfide thin film based on an organosulfur precursor, comprising the steps of:

D. Repeating the steps B to C for a plurality of times until the metal sulfide thin film with the preset thickness is obtained;

the step C specifically comprises the following steps:

after the reaction is finished, introducing inert gas to sweep redundant organic sulfur precursors and reaction byproducts, and generating a metal sulfide monomolecular layer on the surface of the substrate;

the organic sulfur precursor comprises one or more of tert-butyl disulfide, diisopropyl disulfide, diallyl disulfide, diethyl disulfide, di-n-propyl disulfide, diisobutyl disulfide, di-n-butyl disulfide, allyl propyl disulfide, diethyl sulfide, dipropyl sulfide, dibutyl sulfide, allyl methyl sulfide, allyl ethyl sulfide and diallyl sulfide; repeating the steps B to C once, wherein the exposure dose of the metal precursor is 0.001-20 Torr & s, and the exposure dose of the organic sulfur precursor is 0.01-20 Torr & s; the reaction temperature in the step B and the step C is 50-500 ℃; the metal in the metal precursor is nickel.

2. The method of claim 1, wherein the step B comprises:

3. The method according to claim 1, wherein the metal precursor is selected from one or more of bis (nitrogen, nitrogen-di-tert-butylpropanamidino) nickel, bis (nitrogen, nitrogen-diisopropylacetamido) nickel, nickel diacetone, bis (alkyl-cyclopentadienyl) nickel, and bis (2,2,6, 6-tetramethyl-3, 5-heptanedionato) nickel.

4. A metal sulfide thin film based on an organic sulfur precursor, which is prepared by the method for preparing a metal sulfide thin film based on an organic sulfur precursor according to any one of claims 1 to 3.

5. A metal sulfide catalytic electrode comprising a substrate and a metal sulfide thin film disposed on the substrate, the metal sulfide thin film being the organic sulfur precursor-based metal sulfide thin film according to claim 4.

6. The metal sulfide catalytic electrode of claim 5, wherein the substrate is a carbon cloth with carbon nanotubes distributed on the surface.