Photocatalysis in-situ testing device based on near-normal-pressure X-ray photoelectron spectroscopy

Abstract

The utility model discloses a photocatalytic in-situ testing device based on near-normal-pressure X-ray photoelectron spectroscopy. The photocatalytic in-situ testing device comprises a near-normal-pressure XPS (X-ray photoelectron spectroscopy) cavity; the sample table is arranged in the near-normal-pressure XPS cavity; the plurality of micro-leakage valve air inlet systems are in one-to-one correspondence with the plurality of air inlets, and each micro-leakage valve air inlet system is connected to the corresponding air inlet; the vacuumizing system is connected with the air outlet; the external light source is arranged outside the near-normal-pressure XPS cavity, and the working end of the external light source points to the sample table; the working end of the X-ray gun is inserted into the near-normal-pressure XPS cavity and points to the sample table; the energy analyzer and the collection head are inserted into the near-normal-pressure XPS cavity and point to the sample table; and the analysis equipment is electrically connected with the signal output end of the energy analyzer. The in-situ XPS research of photocatalysis in the reaction atmosphere is realized, and the chemical state and the structure of the surface of the catalyst in the reaction atmosphere under the illumination condition can be truly reflected.

Description

Technical Field

[0001] The utility model belongs to the technical field of X-ray photoelectron spectroscopy, and in particular relates to a photocatalytic in-situ testing device based on near-normal-pressure X-ray photoelectron spectroscopy. Background Art

[0002] The invention of near-atmospheric pressure X-ray photoelectron spectroscopy (NAP-XPS) is of great significance for the in-situ study of the surface chemical state and structure of catalysts in the reaction atmosphere, and has been widely used in the in-situ study of thermal catalytic catalysts. Photocatalysis, as an important type of catalytic reaction, is a way of using light energy to transform substances. It is a chemical reaction carried out by substances under the joint action of light and catalysts. Its main application areas include water decomposition, carbon dioxide reduction, water pollution control, nitrogen fixation, organic synthesis, etc. However, in the related research on photocatalytic reactions, there are few reports on the use of NAP-XPS to conduct in-situ studies on photocatalytic reactions. At present, the illumination-XPS test is mainly based on conventional XPS and is carried out in an ultra-high vacuum environment. It is very different from the actual reaction conditions and cannot truly reflect the surface chemical reaction process in the photocatalytic process. It is difficult to meet the testing needs of researchers. Utility Model Content

[0003] The purpose of this application is to provide a photocatalytic in-situ testing device based on near-atmospheric pressure X-ray photoelectron spectroscopy to solve the technical problem in the prior art that the illumination-XPS test is mainly based on conventional XPS testing in an ultra-high vacuum environment, which is very different from the actual reaction conditions and cannot truly reflect the surface chemical reaction process in the photocatalytic process, making it difficult to meet the testing needs of researchers.

[0004] To achieve the above objectives, the present application provides a photocatalytic in-situ testing device based on near-ambient pressure X-ray photoelectron spectroscopy, comprising:

[0005] A near-normal pressure XPS chamber having a plurality of air inlets and a plurality of air outlets;

[0006] A sample stage is arranged in the near-normal pressure XPS chamber and is used to carry the sample;

[0007] A plurality of micro-leakage valve air intake systems corresponding one to each of the plurality of air intake ports, each of the micro-leakage valve air intake systems being connected to a corresponding air intake port;

[0008] a vacuum pumping system connected to the air outlet;

[0009] An external light source is arranged outside the near-normal-pressure XPS chamber, with a working end of the external light source pointing toward the sample stage;

[0010] An X-ray gun, the working end of which is inserted into the near-normal-pressure XPS chamber and pointed toward the sample stage;

[0011] Energy analyzer, the collection head is inserted into the near-normal pressure XPS chamber and pointed toward the sample stage;

[0012] The analyzing device is electrically connected to the signal output terminal of the energy analyzer.

[0013] In one or more embodiments, a transparent area is arranged on the top plate of the near-atmospheric pressure XPS chamber, and the external light source is arranged above the near-atmospheric pressure XPS chamber with its working end pointing toward the transparent area.

[0014] In one or more embodiments, projections of the transparent area, the sample stage, and the external light source in the vertical direction overlap.

[0015] In one or more embodiments, the external light source is extended in a direction perpendicular to the sample stage, so that the external light source is vertically irradiated on the sample stage.

[0016] In one or more embodiments, the X-ray gun and the energy analyzer are respectively arranged on both sides of the external light source, and the extension direction of the X-ray gun and the extension direction of the collection head of the energy analyzer are symmetrically arranged relative to the external light source.

[0017] In one or more embodiments, the plurality of air inlets are vertically arranged in sequence on one side of the bottom of the near-atmospheric pressure XPS chamber, and the air outlet is arranged on the other side of the bottom of the near-atmospheric pressure XPS chamber and is arranged opposite to the plurality of air inlets.

[0018] In one or more embodiments, the external light source is a xenon lamp light source.

[0019] In one or more embodiments, the micro-leak valve intake system includes:

[0020] A gas storage cavity, storing gas therein;

[0021] An air intake pipe, one end of which is connected to the air storage chamber, and the other end of which is connected to the corresponding air intake;

[0022] A micro-leakage valve is arranged on the air inlet pipe to control the pressure of the gas entering the near-normal pressure XPS chamber.

[0023] In one or more embodiments, a heating system is further included, wherein a working end of the heating system is inserted into the near-atmospheric pressure XPS chamber and directed toward the sample stage.

[0024] In one or more embodiments, the heating system includes a laser heating head, which is inserted from the bottom of the near-atmospheric pressure XPS chamber, and the working end of the laser heating head is arranged to point to the bottom surface of the sample stage.

[0025] Compared with the prior art, the application has the beneficial effects that:

[0026] The photocatalytic in-situ testing device of the application realizes in-situ XPS research of photocatalysis in a reaction atmosphere, makes up for the shortcomings of the prior art that cannot apply an atmosphere or can only perform quasi-in-situ testing, and can truly reflect the chemical state and structure of the catalyst surface in the reaction atmosphere under illumination conditions. BRIEF DESCRIPTION OF DRAWINGS

[0027] In order to more clearly illustrate the technical solutions in the embodiments of the application or the prior art, the drawings needed to be used in the embodiments or the prior art description will be briefly introduced. Obviously, the drawings in the following description are only some embodiments described in the application, and for those skilled in the art, other drawings can also be obtained without creative labor on the basis of these drawings.

[0028] Figure 1 is a structural schematic diagram of an embodiment of the photocatalytic in-situ testing device of the application based on near atmospheric pressure X-ray photoelectron spectroscopy;

[0029] Figure 2 is a C1s spectrum of in-situ NAP-XPS of the graphite carbon nitride photocatalytic total water splitting reaction performed by the device of the application;

[0030] Figure 3 is a Cu2p spectrum of in-situ NAP-XPS in the Cu / TiO2 photocatalytic steam reforming reaction performed by the device of the application.

[0031] Main figure mark explanation:

[0032] Near atmospheric pressure XPS cavity 10; gas inlet 101; gas outlet 102; transparent area 103; sample table 104;

[0033] Micro leakage valve gas inlet system 20; gas storage cavity 201; gas inlet pipeline 202; micro leakage valve 203;

[0034] Vacuum pumping system 30;

[0035] X-ray gun 40;

[0036] Energy analyzer 50; collection head 501;

[0037] Analysis device 60;

[0038] External light source 70;

[0039] Laser heating head 80. DETAILED DESCRIPTION

[0040] In order to enable personnel in the technical field to better understand the technical solutions in the present application, the technical solutions in the embodiments of the present application will be clearly and completely described below in combination with the drawings in the embodiments of the present application. Obviously, the described embodiments are only some embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor should belong to the protection scope of the present application.

[0041] Currently, there are two methods for XPS research on photocatalysis. The first method is based on conventional XPS, and the sample is subjected to light irradiation and XPS testing simultaneously in an ultrahigh vacuum environment. The disadvantage is that due to the limitation of the instrument, the testing must be carried out in an ultrahigh vacuum environment, which is very different from the actual reaction conditions, and cannot truly reflect the surface chemical reaction process in the photocatalytic process. The second method is based on XPS to build a quasi-in-situ photocatalytic reaction device. The main method is to use the vacuum system to exhaust and discharge the reaction gas after the sample is subjected to photocatalytic reaction in the reaction chamber, and then transfer the sample to the XPS for testing. The disadvantage is that the photo-generated electrons are generated by light irradiation in the photocatalytic reaction, and the electron-hole separation is achieved. However, the photo-generated electrons are no longer generated due to the removal of the external light irradiation during testing, and the existing electrons and holes will be re-coupled, which cannot truly reflect the effect of the external light irradiation in the photocatalytic process.

[0042] In order to solve the defects of the above two methods, the applicant has developed a photocatalytic in-situ testing device based on near-normal pressure X-ray photoelectron spectroscopy. The device can be used for XPS research on photocatalysis, and can truly reflect the chemical state and structure of the catalyst surface in the reaction atmosphere under light irradiation.

[0043] Specifically, please refer to Figure 1 , Figure 1 is a structural schematic diagram of an embodiment of the photocatalytic in-situ testing device based on near-normal pressure X-ray photoelectron spectroscopy according to the present application.

[0044] As shown in Figure 1 , the photocatalytic in-situ testing device includes a near-normal pressure XPS cavity 10, and a sample stage 104 for carrying a sample is arranged inside the near-normal pressure XPS cavity 10.

[0045] The near-normal pressure XPS cavity 10 has three gas inlets 101 and one gas outlet 102. Each gas inlet 101 is connected with a micro-leak valve gas inlet system 20, and the micro-leak valve gas inlet system 20 is used to inject a near-normal pressure reaction atmosphere into the near-normal pressure XPS cavity 10, so as to simulate the surface chemical state and structure under the catalyst reaction atmosphere.

[0046] The outlet 102 is connected to a vacuum system 30, which is used to draw the interior of the near-atmospheric pressure XPS cavity 10 to an ultra-vacuum state before the injection of the reaction gas and after the end of the reaction, so as to avoid the influence of other gases on the reaction test results.

[0047] It should be noted that in the embodiment, three gas inlets 101 and three micro-leak valve gas systems 20 are arranged in the interior of the near-atmospheric pressure XPS cavity 10. In other embodiments, the number of gas inlets 101 and micro-leak valve gas systems 20 can be adjusted based on the types of gases required for actual tests, and the effects of the embodiment can also be achieved.

[0048] The photocatalytic in-situ test device further comprises an X-ray gun 40, the working end of the X-ray gun 40 is inserted into the interior of the near-atmospheric pressure XPS cavity 10 and is directed towards the sample table 104, which is used to emit X-rays to the sample.

[0049] The photocatalytic in-situ test device further comprises an energy analyzer 50, which comprises a collection head 501 and a signal output end. The collection head 501 is inserted into the interior of the near-atmospheric pressure XPS cavity 10 and is directed towards the sample table 104, which is used to collect the electron energy emitted from the sample; the signal output end is connected to an analysis device 60 to display the analysis results.

[0050] The analysis device 60 can be a computer or other device with built-in test software.

[0051] In order to truly reflect the chemical state and structure of the catalyst surface under light conditions, the photocatalytic in-situ test device further comprises an external light source 70, which is arranged outside the near-atmospheric pressure XPS cavity 10 and has a working end directed towards the sample table 104, so that the light conditions can be continuously applied to the sample during the reaction process.

[0052] The structure of each component in the photocatalytic in-situ test device in the embodiment will be described in detail below.

[0053] In order to ensure the light conditions, in the embodiment, the top plate of the near-atmospheric pressure XPS cavity 10 is provided with a transparent area 103, i.e. a glass window, and the external light source 70 is arranged above the near-atmospheric pressure XPS cavity 10 and has a working end directed towards the transparent area 103.

[0054] Further, in the embodiment, the transparent area 103, the sample table 104 and the external light source 70 are vertically overlapped, so that the external light source 70 can be arranged in a direction perpendicular to the sample table 104, and the external light source 70 can be vertically irradiated on the sample table 104, thereby ensuring the best light conditions.

[0055] In order to ensure the illumination effect, the external light source 70 is a xenon lamp light source in the embodiment, and in other embodiments, a suitable external light source 70 can be selected based on actual needs, and the effects of the embodiment can be achieved.

[0056] In order to ensure the detection effect, the X-ray gun 40 and the energy analyzer 50 are arranged on the two sides of the external light source 70 in the embodiment, and the extension direction of the X-ray gun 40 and the extension direction of the collection head 501 of the energy analyzer 50 are symmetrically arranged relative to the external light source 70.

[0057] Based on the above scheme, the collection rate of the electron energy emitted by the sample can be improved, which helps to improve the analysis effect.

[0058] In order to optimize the gas inlet and vacuum effect inside the near-normal-pressure XPS cavity 10, the three gas inlets 101 are arranged in the vertical direction on one side of the bottom of the near-normal-pressure XPS cavity 10, and the gas outlet 102 is arranged on the other side of the bottom of the near-normal-pressure XPS cavity 10, and the gas outlet 102 and the three gas inlets 101 are arranged opposite to each other.

[0059] The micro-leak valve gas inlet system 20 in the embodiment includes a gas storage cavity 201 in which gas is stored, one end of the gas storage cavity 201 is connected with a gas inlet pipeline 202, the other end of the gas inlet pipeline 202 is connected to the corresponding gas inlet 101, and a micro-leak valve 203 is arranged on the gas inlet pipeline 202 to control the gas pressure entering the near-normal-pressure XPS cavity 10.

[0060] The gas stored in the gas storage cavity 201 is used to simulate the real reaction atmosphere, and the gas can be water vapor, methanol water vapor, etc. according to different detection targets, which can be adjusted according to actual needs.

[0061] In order to be applicable to the catalyst reaction that needs to be heated, the photocatalytic in-situ testing device in the embodiment further includes a heating system, and the working end of the heating system is inserted into the near-normal-pressure XPS cavity 10 and is arranged to point to the sample table 104, so as to heat the sample on the sample table 104 during the reaction.

[0062] Specifically, the heating system in the embodiment includes a laser heating head 80, the laser heating head 80 is inserted from the bottom of the near-normal-pressure XPS cavity 10, and the working end of the laser heating head 80 is arranged to point to the bottom surface of the sample table 104, avoiding affecting the work of the X-ray gun 40, the energy analyzer 50 and the external light source 70.

[0063] The photocatalytic in-situ testing device based on the above embodiments realizes in-situ XPS research of photocatalysis in a reaction atmosphere, makes up for the shortcomings of the existing schemes that cannot apply an atmosphere or can only perform quasi-in-situ testing, and can truly reflect the chemical state and structure of the catalyst surface in the reaction atmosphere under illumination conditions.

[0064] The effects of the technical solutions of the present application will be further described in detail below in combination with specific embodiments.

[0065] Example 1: In-situ NAP-XPS study of graphite carbon nitride (CN) photocatalytic overall water splitting reaction

[0066] (1) The CN catalyst sample was transferred into the near-atmospheric pressure XPS chamber, and water vapor (H2O) at a pressure of 0.2 mbar was introduced through a microleak valve. NAP-XPS test was performed as a background before light irradiation.

[0067] (2) The external light source focused on the sample surface through the glass window outside the near-atmospheric pressure XPS chamber was turned on, and the sample was irradiated in the water vapor atmosphere, while the in-situ NAP-XPS test was performed.

[0068] (3) After the reaction was completed, the external light source was turned off, the microleak valve was closed, and the water vapor was evacuated to an ultrahigh vacuum state, and the CN sample was transferred out.

[0069] (4) The fluorinated CN catalyst (F0.1-CN) was replaced, and steps (1) and (2) were repeated.

[0070] The test data of the above experiment can be found in Figure 2 , Figure 2 is the C1s spectrum of the in-situ NAP-XPS of the graphite carbon nitride photocatalytic overall water splitting reaction by the device of the present application, and a and b in the figure are the CN catalyst and the F 0.1 -CN catalyst, respectively, after NAP-XPS test under water vapor atmosphere at a pressure of 0.2 mbar without light irradiation, light irradiation for 0 minutes, light irradiation for 5 minutes, light irradiation for 10 minutes, and light irradiation for 15 minutes.

[0071] As shown in a of Figure 2 , with the increase of light irradiation time, the carbon-carbon peak (C-C) and the carbon-nitrogen peak (C-N) in the C1s spectrum of the CN catalyst sample gradually shift to 285.0 eV and 288.3 eV from 284.4 eV and 287.7 eV in the high binding energy direction, indicating that the catalyst is gradually oxidized and deactivated in the photocatalytic overall water splitting reaction.

[0072] As shown in b of Figure 2 , with the increase of light irradiation time, the carbon-carbon peak (C-C) and the carbon-nitrogen peak (C-N) in the C1s spectrum of the F 0.1 -CN catalyst sample do not shift, indicating that fluorination of the CN catalyst can effectively inhibit its oxidation and deactivation during the reaction.

[0073] Example 2: In-situ NAP-XPS study of titanium dioxide supported copper catalyst (Cu / TiO2) photocatalytic methane steam reforming reaction

[0074] (1) The Cu / TiO2 catalyst sample was transferred to a near-normal pressure XPS chamber, hydrogen was introduced at a pressure of 0.3 mbar using a micro-leak valve, and the sample was heated to 350°C using a laser heating head to pretreat the catalyst. In situ NAP-XPS testing was also performed.

[0075] (2) After the pretreatment, the laser heating head was turned off, the micro-leak valve was closed, the hydrogen was evacuated to an ultra-high vacuum state, and a methanol aqueous solution (CH3OH+H2O) vapor atmosphere with a pressure of 0.3 mbar was reintroduced. The laser heating head was then turned on again to heat the sample to 170°C to simulate the reaction conditions in the actual photocatalytic methane steam reforming reaction. At the same time, an in situ NAP-XPS test was performed as a background before illumination.

[0076] (3) Open the near-atmospheric pressure XPS chamber and focus an external light source on the sample surface through a glass window to irradiate the sample in a methanol-water vapor atmosphere, while performing in-situ NAP-XPS testing;

[0077] (4) After the reaction is completed, turn off the external light source, close the micro-leak valve, evacuate the water vapor to an ultra-high vacuum state, and transfer the Cu / TiO2 sample.

[0078] For the test data of the above experiment, please refer to Figure 3 , Figure 3 This is the in situ NAP-XPS Cu 2p spectrum of the Cu / TiO2 photocatalytic methane steam reforming reaction performed by the device of the present application. In the figure, a, b, and c are the NAP-XPS Cu 2p spectra under three different conditions: 0.3 mbar pressure H2 atmosphere + 350°C heating, unilluminated methanol aqueous solution vapor atmosphere + 170°C heating, and illuminated methanol aqueous solution (CH3OH+H2O) vapor atmosphere + 170°C heating.

[0079] like Figure 3 As shown in Figure a, after the Cu / TiO2 catalyst was reduced with H2 at 350℃, only 0-valent metal Cu (932.7eV) was present. Figure 3 As shown in Figure b, a satellite peak (947.0 eV) corresponding to 1-valent Cu was detected on the Cu / TiO2 catalyst after methanol solution vapor was introduced; Figure 3 As shown in Figure c, after the Cu / TiO2 catalyst is exposed to light, the Cu 2p spectrum returns to metallic Cu.

[0080] The above in situ NAP-XPS experimental results show that metallic Cu is the actual active phase in the photocatalytic methanol reforming reaction. Figure 3 Zhongb and Figure 3The experimental results of the middle C can show that if the non-in-situ or quasi-in-situ XPS is used for testing, the wrong conclusion that the active phase is oxidized 1-valence Cu can be obtained, which further illustrates the importance of NAP-XPS combined with in-situ photocatalytic study of light.

[0081] It is apparent for a person skilled in the art that the present application is not limited to the details of the above-described exemplary embodiments, but that it can be implemented in other embodiments without deviating from the spirit or essential characteristics of the application. Therefore, the embodiments should be considered in all respects as illustrative and not restrictive, the scope of the application being indicated by the appended claims rather than by the above description, and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein. Any reference signs in the claims should not be construed as limiting the claim concerned.

[0082] In addition, it should be understood that, although the present specification is described in terms of embodiments, not every embodiment contains only one independent technical solution, and the description of the specification is only for the sake of clarity, and those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can be appropriately combined to form other embodiments that those skilled in the art can understand.

Claims

1. A photocatalytic in-situ testing device based on near-ambient pressure X-ray photoelectron spectroscopy, characterized in that: include: A near-normal pressure XPS chamber having a plurality of air inlets and a plurality of air outlets; A sample stage is arranged in the near-normal pressure XPS chamber and is used to carry the sample; A plurality of micro-leakage valve air intake systems corresponding one to each of the plurality of air intake ports, each of the micro-leakage valve air intake systems being connected to a corresponding air intake port; a vacuum pumping system connected to the air outlet; An external light source is arranged outside the near-normal-pressure XPS chamber, with a working end of the external light source pointing toward the sample stage; An X-ray gun, the working end of which is inserted into the near-normal-pressure XPS chamber and pointed toward the sample stage; Energy analyzer, the collection head is inserted into the near-normal pressure XPS chamber and pointed toward the sample stage; The analyzing device is electrically connected to the signal output terminal of the energy analyzer.

2. The photocatalytic in-situ testing device according to claim 1, characterized in that: A transparent area is arranged on the top plate of the near-normal-pressure XPS chamber, and the external light source is arranged above the near-normal-pressure XPS chamber, with the working end pointing toward the transparent area.

3. The photocatalytic in-situ testing device according to claim 2, characterized in that: The projections of the transparent area, the sample stage and the external light source in the vertical direction overlap.

4. The photocatalytic in-situ testing device according to claim 1, characterized in that: The external light source is extended in a direction perpendicular to the sample stage, so that the external light source is vertically irradiated on the sample stage.

5. The photocatalytic in-situ testing device according to claim 4, characterized in that: The X-ray gun and the energy analyzer are respectively arranged on both sides of the external light source, and the extension direction of the X-ray gun and the extension direction of the collection head of the energy analyzer are symmetrically arranged relative to the external light source.

6. The photocatalytic in-situ testing device according to claim 1, characterized in that: The plurality of air inlets are vertically arranged in sequence on one side of the bottom of the near-normal-pressure XPS chamber, and the air outlet is arranged on the other side of the bottom of the near-normal-pressure XPS chamber and is arranged opposite to the plurality of air inlets.

7. The photocatalytic in-situ testing device according to claim 1, characterized in that: The external light source is a xenon lamp light source.

8. The photocatalytic in-situ testing device according to claim 1, characterized in that: The micro-leakage valve air intake system comprises: A gas storage cavity, storing gas therein; An air intake pipe, one end of which is connected to the air storage chamber, and the other end of which is connected to the corresponding air intake; A micro-leakage valve is arranged on the air inlet pipe to control the pressure of the gas entering the near-normal pressure XPS chamber.

9. The photocatalytic in-situ testing device according to claim 1, characterized in that: It also includes a heating system, wherein the working end of the heating system is inserted into the near-normal pressure XPS chamber and points to the sample stage.

10. The photocatalytic in-situ testing device according to claim 9, characterized in that: The heating system includes a laser heating head, which is inserted from the bottom of the near-normal-pressure XPS chamber, and the working end of the laser heating head is arranged to point to the bottom surface of the sample stage.

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