Preparation method of wide-band-gap nitrogen-atom-doped non-benzene type graphene nanobelt

Abstract

The invention relates to a preparation method of a wide-band-gap nitrogen atom doped non-benzene type graphene nanobelt, and belongs to the technical field of surface synthesis. The method comprises the following steps: depositing 1, 8-dibromo-9H-carbazole precursor molecules on the surface of a gold substrate by utilizing a strategy that the 1, 8-dibromo-9H-carbazole precursor molecules can generate intramolecular dehalogenation coupling and cyclization dehydrogenation under the catalytic action of the gold substrate, preserving heat for 20-40 minutes at the temperature of 200 DEG C, and then cooling a sample to room temperature to obtain a one-dimensional polymer chain. And then carrying out heat preservation on the one-dimensional molecular chain sample at the temperature of 400 DEG C for 20-40 minutes to obtain the nitrogen atom doped non-benzene type graphene nanobelt. The prepared nitrogen atom doped non-benzene type graphene nanometre has a band gap of 3.55 electron volts, and belongs to a broadband semiconductor.

Description

Technical Field

[0001] The invention relates to a method for preparing a wide-bandgap nitrogen-atom-doped non-benzene-type graphene nanoribbon, belonging to the technical field of surface synthesis. Background Art

[0002] In recent decades, with the development of surface science and technology, scanning tunneling microscopy has become one of the effective tools for observing and analyzing surface reactions. It can obtain three-dimensional images of sample surfaces in real space in real time, and can be used to study periodic or non-periodic surface structures. In addition, information about the surface electronic structure can be obtained in conjunction with scanning tunneling spectroscopy. With the help of the precise imaging function and powerful spectroscopy function of scanning tunneling microscopy, we can more intuitively understand the reaction path and reaction mechanism of the entire surface reaction.

[0003] One-dimensional graphene nanoribbons have attracted extensive attention in the past decade due to their interesting electronic properties and potential applications in nanoelectronic devices. To achieve graphene nanoribbons with precisely defined width and edge structures (i.e., armchair, zigzag, or concave edges), two bottom-up synthetic strategies, namely, surface synthesis and solution synthesis, have been developed. Compared with solution-based synthesis methods, surface synthesis based on scanning tunneling microscopy shows substantial advantages in characterization, such as chemical structure identification and electronic structure measurement in real space.

[0004] Most of the graphene nanoribbons synthesized so far focus on the all-benzene structure, and there are few studies on non-benzene graphene nanoribbons and the doping of non-benzene graphene nanoribbons. Theoretical studies have shown that non-benzene graphene nanoribbons have different properties from all-benzene graphene nanoribbons, and have very broad application prospects in optoelectronics, transportation, and sensing. However, experimental studies on non-benzene graphene nanoribbons are very rare. This is mainly because the growth of non-benzene graphene nanoribbons with atomically precise control is very difficult. Summary of the invention

[0005] In view of the problems and shortcomings of the above-mentioned prior art, the present invention provides a wide-gap nitrogen-doped non-benzene graphene nanoribbon and a preparation method thereof. The present invention uses two strategies: 1. 1,8-dibromo-9H-carbazole precursor undergoes an Ullmann reaction on the surface of a gold single crystal to form a polymer chain; 2. The polymer chain undergoes a dehydrogenation cyclization reaction at high temperature to form a nitrogen-doped non-benzene graphene nanoribbon. The present invention is implemented by the following technical solutions.

[0006] A method for preparing a wide-bandgap nitrogen-doped non-benzene graphene nanoribbon, the specific steps of which include:

[0007] Step 1, preparing a gold single crystal substrate;

[0008] Step 2, 1,8-dibromo-9H-carbazole precursor molecules are evaporated and deposited on the gold single crystal substrate in step 1 to obtain a substrate and an assembly structure deposited on the substrate, and the temperature on the substrate is controlled to be 25-30° C. during the deposition process;

[0009] Step 3, subjecting the substrate of step 2 and the assembled structure deposited on the substrate to a first heating and holding treatment to obtain a one-dimensional nitrogen-doped polymer chain;

[0010] Step 4, subjecting the polymer chain sample of step 3 to a second heating and heat preservation treatment to obtain a one-dimensional nitrogen atom-doped non-benzene graphene nanoribbon;

[0011] The preparation process of the gold single crystal substrate is specifically as follows:

[0012] Step 1.1, in an ultra-high vacuum chamber, subjecting a gold substrate to argon ion sputtering to obtain a gold base;

[0013] Step 1.2: Heat the gold substrate obtained in step 1.1 to 430°C and keep it warm for 10-30 minutes to obtain a gold single crystal substrate.

[0014] In the step 2, the evaporation temperature of the 1,8-dibromo-9H-carbazole precursor molecules is 50° C.-60° C., and the deposition time is 2 minutes-5 minutes.

[0015] The step 3 and step 4 are gradually heated up to 200° C. and kept warm for 20-40 minutes; and then heated up to 400° C. and kept warm for 20-40 minutes.

[0016] The beneficial effects of the present invention are:

[0017] (1) The present invention can prepare a one-dimensional nitrogen-doped graphene polymer chain;

[0018] (2) One-dimensional nitrogen atom-doped non-benzene-type graphene nanoribbons prepared by the present invention;

[0019] (3) The nitrogen atom-doped non-benzene graphene nanoribbon prepared in the present invention is a wide bandgap semiconductor with a bandgap of about 3.55 electron volts. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 is a scanning tunneling microscope image of the self-assembled structure prepared in Example 1 of the present invention;

[0021] Figure 2 This is a scanning tunneling microscope image of a one-dimensional nitrogen-doped polymer chain prepared by the present invention;

[0022] Figure 3This is a scanning tunneling microscope image of a one-dimensional nitrogen atom-doped non-benzene-type graphene nanoribbon prepared with atomic-level precision in the present invention.

[0023] Figure 4 This is a scanning tunneling microscopic spectrum image of the one-dimensional nitrogen atom-doped non-benzene-type graphene nanoribbon prepared with atomic-level precision in the present invention.

[0024] Figure 5 It is a schematic diagram of the preparation principle of the present invention. DETAILED DESCRIPTION

[0025] The present invention will be further described below in conjunction with the accompanying drawings and specific implementation methods.

[0026] Test instruments and equipment:

[0027] Low-temperature scanning tunneling microscope: purchased from Omicron, Germany.

[0028] K-cell molecular evaporation source: purchased from Omicron, Germany.

[0029] Argon ion gun: purchased from Omicron, Germany.

[0030] raw material:

[0031] 1,8-Dibromo-9H-carbazole precursor molecule was purchased from Bitart Pharmaceuticals with a purity of 99.9%.

[0032] Gold single crystal: purchased from MaTecK, purity 99.999%.

[0033] Example 1

[0034] A method for preparing a wide-bandgap nitrogen-doped non-benzene graphene nanoribbon, the specific steps of which include:

[0035] Step 1: preparing a gold single crystal substrate; the preparation process of the gold single crystal substrate is specifically as follows:

[0036] Step 1.1, in an ultra-high vacuum chamber, subjecting a gold substrate to argon ion sputtering to obtain a gold base;

[0037] Step 1.2, heating the gold substrate obtained in step 1.1 to 430° C. and keeping the temperature for 10 minutes to obtain a gold single crystal substrate;

[0038] Step 2, 50 mg of 1,8-dibromo-9H-carbazole precursor molecules are evaporated at 55° C. using a thermal resistance K-cell molecular evaporation source and deposited on the 50 g gold single crystal substrate in step 1 to obtain a self-assembled structure of the substrate and the 1,8-dibromo-9H-carbazole precursor molecules deposited on the substrate. The temperature of the gold single crystal substrate is controlled to be 30° C. during the deposition process, and the deposition time is 5 minutes;

[0039] Step 3, heating the substrate of step 2 and the self-assembly deposited on the substrate to the growth temperature for the first time and heat preservation treatment to obtain a one-dimensional nitrogen-doped polymer chain; the growth temperature is 250° C. and the temperature is kept for 30 minutes;

[0040] Step 4, then heating the substrate in step 3 and the one-dimensional nitrogen-doped graphene polymer chain deposited on the substrate to the growth temperature for a second time for heat preservation treatment; the growth temperature is 350° C. and the temperature is kept for 30 minutes;

[0041] Step 5: Characterize the electrical properties of the nitrogen atom-doped non-benzene graphene nanoribbon obtained in step 4, and measure the electronic structure of the broadband semiconductor.

[0042] The scanning tunneling microscope image of the self-assembled structure of the 1,8-dibromo-9H-carbazole molecule prepared in this example is as follows: Figure 1 As shown, from Figure 1 High-quality, neatly arranged self-assembled structures can be seen.

[0043] The scanning tunneling microscope image of the one-dimensional nitrogen-doped polymer chain prepared in this example is as follows: Figure 2 shown.

[0044] The scanning tunneling microscope image of the nitrogen atom-doped non-benzene graphene nanoribbon prepared in this example is as follows: Figure 3 shown.

[0045] The scanning tunneling microscopy spectrum of the nitrogen atom-doped non-benzene graphene nanoribbons prepared in this example is shown in FIG. Figure 4 shown.

[0046] Example 2

[0047] A method for preparing a wide-bandgap nitrogen-doped non-benzene graphene nanoribbon, the specific steps of which include:

[0048] Step 1: preparing a gold single crystal substrate; the preparation process of the gold single crystal substrate is specifically as follows:

[0049] Step 1.1, in an ultra-high vacuum chamber, subjecting a gold substrate to argon ion sputtering to obtain a gold base;

[0050] Step 1.2, heating the gold substrate obtained in step 1.1 to 430° C. and keeping the temperature for 10 minutes to obtain a gold single crystal substrate;

[0051] Step 2, 50 mg of 1,8-dibromo-9H-carbazole precursor molecules are evaporated at 60° C. using a thermal resistance K-cell molecular evaporation source and deposited on the 50 g gold single crystal substrate in step 1 to obtain a self-assembled structure of the substrate and the 1,8-dibromo-9H-carbazole precursor molecules deposited on the substrate. The temperature of the gold single crystal substrate is controlled to be 30° C. during the deposition process, and the deposition time is 2 minutes;

[0052] Step 3, heating the substrate of step 2 and the self-assembly deposited on the substrate to the growth temperature for the first time and heat preservation treatment to obtain a one-dimensional nitrogen-doped polymer chain; the growth temperature is 250° C. and the temperature is kept for 30 minutes;

[0053] Step 4, then heating the substrate in step 3 and the one-dimensional nitrogen-doped polymer chain deposited on the substrate to the growth temperature for a second time and keeping the temperature; the growth temperature is 350° C. and the temperature is kept for 30 minutes;

[0054] Step 5: Characterize the electrical properties of the nitrogen atom-doped non-benzene graphene nanoribbon obtained in step 4, and measure the electronic structure of the broadband semiconductor.

[0055] Example 3

[0056] A method for preparing a wide-bandgap nitrogen-doped non-benzene graphene nanoribbon, the specific steps of which include:

[0057] Step 1: preparing a gold single crystal substrate; the preparation process of the gold single crystal substrate is specifically as follows:

[0058] Step 1.1, in an ultra-high vacuum chamber, subjecting a gold substrate to argon ion sputtering to obtain a gold base;

[0059] Step 1.2, heating the gold substrate obtained in step 1.1 to 430° C. and keeping the temperature for 10 minutes to obtain a gold single crystal substrate;

[0060] Step 2, 50 mg of 1,8-dibromo-9H-carbazole precursor molecules are evaporated at 50° C. using a thermal resistance K-cell molecular evaporation source and deposited on the 50 g gold single crystal substrate in step 1 to obtain a self-assembled structure of the substrate and the 1,8-dibromo-9H-carbazole precursor molecules deposited on the substrate. The temperature of the gold single crystal substrate is controlled to be 30° C. during the deposition process, and the deposition time is 20 minutes;

[0061] Step 3, heating the substrate of step 2 and the self-assembly deposited on the substrate to the growth temperature for the first time and heat preservation treatment to obtain a one-dimensional nitrogen-doped polymer chain; the growth temperature is 250° C. and the temperature is kept for 30 minutes;

[0062] Step 4, then heating the substrate in step 3 and the one-dimensional nitrogen-doped polymer chain deposited on the substrate to the growth temperature for a second time and keeping the temperature; the growth temperature is 350° C. and the temperature is kept for 30 minutes;

[0063] Step 5: Characterize the electrical properties of the nitrogen atom-doped non-benzene graphene nanoribbon obtained in step 4, and measure the electronic structure of the broadband semiconductor.

[0064] The specific implementation modes of the present invention are described in detail above in conjunction with the accompanying drawings, but the present invention is not limited to the above implementation modes, and various changes can be made within the knowledge scope of ordinary technicians in this field without departing from the purpose of the present invention.

Claims

1. A method for preparing a wide-bandgap nitrogen-doped non-benzene graphene nanoribbon, characterized in that the steps include: Step 1, preparing a gold single crystal substrate; Step 2, depositing 1,8-dibromo-9H-carbazole precursor molecules onto a gold single crystal substrate maintained at room temperature by molecular beam epitaxy technology, heating to 200° C., and keeping the temperature for 20-40 minutes to obtain a one-dimensional polymer chain; Step 3: heating the one-dimensional polymer chain sample obtained in step 2 to 400° C. and keeping the temperature for 20-40 minutes to obtain nitrogen atom-doped non-benzene graphene nanoribbons.

2. The method for preparing a wide-gap nitrogen-doped non-benzene graphene nanoribbon according to claim 1, characterized in that The preparation process of the gold single crystal substrate is as follows: Step 1.1, in an ultra-high vacuum chamber, subjecting a gold substrate to argon ion sputtering treatment to obtain a gold substrate; Step 1.2: Heat the gold substrate obtained in step 1.1 to 480°C and keep it warm for 20-30 minutes to obtain a clean gold single crystal substrate.

3. The method for preparing a wide-gap nitrogen-doped non-benzene graphene nanoribbon according to claim 1, characterized in that: In the step 2, the evaporation temperature of the 1,8-dibromo-9H-carbazole precursor molecules is 50° C.-60° C., and the deposition time is 2 minutes-5 minutes.

4. The method for preparing a wide-gap nitrogen-doped non-benzene graphene nanoribbon according to claim 1, characterized in that: The band gap of the nitrogen atom-doped non-benzene-type graphene nanoribbon is 3.55 electron volts.

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