A potential-type hydrogen gas sensor and a method for manufacturing the same

Abstract

The application is suitable for the field of gas sensor detection, and provides a potential type hydrogen sensor and a preparation method thereof; the potential type hydrogen sensor comprises a zinc oxide nanocage sensitive electrode, a reference electrode, a solid electrolyte and a ceramic plate with a heating element, the heating element is used for heating the solid electrolyte, the sensitive electrode and the reference electrode; the solid electrolyte is installed on the ceramic plate, the zinc oxide nanocage sensitive electrode and the reference electrode are located on the surface of the solid electrolyte; the zinc oxide nanocage sensitive electrode is made of nanocage-shaped zinc oxide electrode material; the application takes the zinc oxide nanocage as the sensitive electrode, significantly improves the response value to hydrogen, and the response value to 20ppm hydrogen is increased by 11.6 times; compared with the existing most advanced potential type hydrogen sensor, the application also has obviously higher response, and has more advantages in low concentration hydrogen detection.

Description

Technical Field

[0001] This invention relates to the field of gas sensor detection, specifically a potential-type hydrogen sensor and its preparation method. Background Technology

[0002] Hydrogen has advantages such as high combustion efficiency and no pollution byproducts, and is considered one of the three major new energy sources along with solar and nuclear energy. However, because hydrogen molecules are very small, leaks are prone to occur during production, storage, transportation, and use; hydrogen is colorless and odorless, making it difficult to detect; and the explosive limits of hydrogen in air are 4% to 75%. Therefore, hydrogen poses a great danger, and its content must be detected in real time with high sensitivity during any process involving its use.

[0003] Solid electrolyte-based potentiometric hydrogen sensors have advantages such as being all-solid-state, simple in structure, low in cost, and resistant to high temperatures, making them one of the most widely studied gas sensors. However, existing potentiometric hydrogen sensors still suffer from low response values ​​and low sensitivity, making them unable to effectively detect low concentrations of hydrogen. Summary of the Invention

[0004] The purpose of this invention is to provide a potential-type hydrogen sensor to solve the problems mentioned in the background art.

[0005] To achieve the above objectives, the present invention provides the following technical solution:

[0006] A potential-type hydrogen sensor includes: a zinc oxide nanocage sensitive electrode, a reference electrode, a solid electrolyte, and a ceramic plate with a heating element. The heating element is used to heat the solid electrolyte, the sensitive electrode, and the reference electrode. The solid electrolyte is mounted on the ceramic plate, and the zinc oxide nanocage sensitive electrode and the reference electrode are located on the surface of the solid electrolyte. The zinc oxide nanocage sensitive electrode is made of a nanocage-shaped zinc oxide electrode material.

[0007] As a further aspect of the present invention, the solid electrolyte is bonded to a ceramic plate using an adhesive.

[0008] The present invention provides another technical solution as follows:

[0009] A method for fabricating a potential-type hydrogen sensor includes the following steps:

[0010] Step S21: Prepare the reference electrode;

[0011] Step S22: Prepare nanocage-shaped zinc oxide electrode paste;

[0012] Step S23: Prepare zinc oxide nanocage sensitive electrode;

[0013] Step S24: Use dotted Ag paste to attach two Pt wires to the reference electrode and the zinc oxide nanocage sensitive electrode respectively as electrode leads;

[0014] Step S25: Assemble the lower surface of the solid electrolyte and the ceramic plate with the heating element to obtain the device;

[0015] Step S26: Solder and package the obtained device to obtain a potential-type hydrogen sensor.

[0016] As a further aspect of the present invention: before step S21, the method further includes: preparing a solid electrolyte, specifically including:

[0017] GDC powder was synthesized via a citric acid-nitrate self-propagating combustion method.

[0018] GDC powder is ball-milled for 20-28 hours, then an appropriate amount of PVA solution is added and milled for 1.5-2.5 hours. Finally, 0.5-0.7 g of powder is pressed into shape under 10 MPa pressure and sintered at 1200-1800℃ for 8-12 hours to obtain a solid electrolyte.

[0019] As a further aspect of the present invention, a method for preparing a nanocage-like zinc oxide electrode material includes the following steps:

[0020] Step S11: Synthesize ZIF-8 self-sacrificing template;

[0021] Step S12: Calcine the ZIF-8 self-sacrificing template in air to obtain nanocage-shaped zinc oxide electrode material.

[0022] As a further aspect of the present invention: the method for preparing the ZIF-8 self-sacrificial template includes the following steps:

[0023] Step S111: Weigh zinc acetate, 2-methylimidazole and deionized water according to the stoichiometric ratio of 1:25-35:1600-1900;

[0024] Step S112: Dissolve zinc acetate and 2-methylimidazole in deionized water, mix and stir for 8-12 min, and then add hexadecyltrimethylammonium bromide (CTAB) to obtain a hydrothermal precursor solution;

[0025] Step S113: Pour the precursor solution into the polymerization reactor and place it at 100-140℃ for hydrothermal synthesis for 20-28 hours. Then filter, wash and dry the product to obtain ZIF-8 self-sacrificing template.

[0026] As a further embodiment of the present invention: the mass ratio of the amount of CTAB added to zinc ions is 0wt% ≤ CTAB / Zn ≤ 0.5wt%.

[0027] As a further aspect of the present invention: the preparation of the reference electrode includes the following steps:

[0028] The first raw material slurry is coated onto the solid electrolyte 1 and kept at 120-180℃ for 20-40 minutes to allow the organic solvent in the Pt slurry to evaporate completely. Then, the electrolyte substrate 1 is calcined at 800-1200℃ for 20-40 minutes to form a reference electrode.

[0029] As a further aspect of the present invention: the preparation of the nanocage-like zinc oxide electrode slurry includes the following steps:

[0030] Terpineol and ethyl cellulose are mixed at a mass ratio of 5-13:1 to obtain modified terpineol; nanocage-shaped zinc oxide electrode material is weighed, the modified terpineol is added dropwise, and then the mixture is thoroughly ground for 0.6-1.4 hours to obtain nanocage-shaped zinc oxide electrode slurry.

[0031] As a further aspect of the present invention: the preparation of the zinc oxide nanocage sensitive electrode includes the following steps:

[0032] The prepared nanocage-shaped zinc oxide electrode slurry is coated on the solid electrolyte 1, with the reference electrode 3 on the same side of the solid electrolyte 1. Then, it is placed at 120-180℃ for 20-40 minutes to allow the organic solvent in the electrode slurry to evaporate completely. The solid electrolyte 1 is then calcined at 550-650℃ for 2.5-3.5 hours to form a zinc oxide nanocage sensitive electrode.

[0033] Compared with the prior art, the beneficial effects of the present invention are:

[0034] 1. Compared with conventional potentiometric hydrogen sensors based on zinc oxide nanoparticles as sensitive electrodes, this invention uses zinc oxide nanocages as sensitive electrodes, which significantly improves the response value to hydrogen, increasing the response value to 20ppm hydrogen by 11.6 times. Compared with the most advanced potentiometric hydrogen sensors currently available, this invention also has a significantly higher response and is more advantageous in the detection of low-concentration hydrogen.

[0035] 2. The zinc oxide nanocage sensitive electrode in this invention has a highly tunable morphology. By changing the amount of CTAB added, the morphology of the sensitive electrode can be easily controlled, improving the sensitivity to hydrogen. This simple and effective method achieves high response and high sensitivity detection of hydrogen.

[0036] 3. The potential-type hydrogen sensor involved in this invention has a flat panel structure. Its main components include only a sensitive electrode, a reference electrode, a solid electrolyte, and a ceramic heating plate. Its structure is simple, its manufacturing process is easy, and it is easy to miniaturize and integrate, which is beneficial for mass production and practical application. Attached Figure Description

[0037] Figure 1 This is a schematic diagram of the structure of a potential-type hydrogen sensor according to an embodiment of the present invention.

[0038] Figure 2 The XRD patterns are of the nanocage-like zinc oxide sensitive electrode materials prepared in this invention with three different CTAB addition amounts and conventional zinc oxide nanoparticles (used as a comparison).

[0039] Figure 3 SEM images of the nanocage-like zinc oxide sensitive electrode materials prepared in this invention with three different CTAB addition amounts and conventional zinc oxide nanoparticles (used as a comparison).

[0040] Figure 4 The dynamic response recovery curves of a potential-type hydrogen sensor based on three nanocage-shaped zinc oxide sensing electrodes and a conventional zinc oxide nanoparticle sensing electrode (used as a comparison) at 450 °C to different concentrations of hydrogen are shown.

[0041] Figure 5 The relationship between the response values ​​of a potential-type hydrogen sensor based on three nanocage-shaped zinc oxide sensing electrodes and a conventional zinc oxide nanoparticle sensing electrode (used as a comparison) to different concentrations of hydrogen at 450 °C and the logarithm of the concentration.

[0042] In the figure: solid electrolyte-1, zinc oxide nanocage sensitive electrode-2, reference electrode-3, Ag point-4, Pt wire-5, ceramic plate-6, heating element-7, adhesive-8. Detailed Implementation

[0043] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0044] According to the response mechanism of potentiometric hydrogen sensors, the sensor's response value to hydrogen mainly depends on the heterogeneous catalytic reaction of hydrogen on the surface of the sensitive electrode and the electrochemical catalytic reaction of hydrogen at the three-phase interface (gas / electrolyte / electrode). Currently, the main methods to improve gas response value and sensitivity include developing high-performance sensitive materials and optimizing the sensor microstructure. While microstructure has a significant impact on gas sensing performance, it has been less studied. Since the target gas is consumed by heterogeneous catalytic reactions during diffusion within the sensitive electrode, reducing the effective hydrogen concentration at the three-phase interface, it is detrimental to high response and sensitivity to hydrogen. Therefore, developing porous sensitive electrodes with special morphologies to reduce or suppress heterogeneous catalytic reactions on the sensitive electrode surface is of great significance for further improving the sensitivity characteristics of potentiometric hydrogen sensors. The potentiometric hydrogen sensor provided by this invention can effectively reduce heterogeneous catalytic reactions on the surface of the sensitive electrode, increase the effective hydrogen concentration and electrochemical catalytic reaction at the three-phase interface, and thus improve the sensor's sensitivity to hydrogen.

[0045] Please see Figure 1 The present invention provides a structural diagram of a potential-type hydrogen sensor, comprising: a zinc oxide nanocage sensitive electrode 2, a reference electrode 3, a solid electrolyte 1, and a ceramic plate 6 with a heating element 7. The heating element 7 is used to heat the reference electrode 3. The heating element of the reference electrode 3 provides the operating temperature for this potential-type hydrogen sensor. The solid electrolyte 1 is mounted on the ceramic plate 6, and the zinc oxide nanocage sensitive electrode 2 and the reference electrode 3 are located on the surface of the solid electrolyte 1. The zinc oxide nanocage sensitive electrode 2 is made of a nanocage-shaped zinc oxide electrode material.

[0046] This invention enables real-time response to hydrogen by collecting the potential difference change between the zinc oxide nanocage sensitive electrode 2 and the reference electrode 3 in a hydrogen leak atmosphere, thereby obtaining hydrogen concentration data in the environment.

[0047] It should be noted that the ceramic plate 6 can be an alumina ceramic plate. This configuration is easy to implement.

[0048] It should be noted that the solid electrolyte 1 is bonded to the ceramic plate 6 using adhesive 8, which facilitates the fixation of the solid electrolyte 1. The adhesive 8 can be any type of adhesive. Of course, the solid electrolyte 1 can also be fixed to the ceramic plate 6 using other methods.

[0049] The reference electrode 3 can be made of the noble metal Pt; the solid electrolyte 1 can be made of GDC.

[0050] The reference electrode 3 is provided with a Pt wire 5, and the zinc oxide nanocage sensitive electrode 2 is provided with an Ag point 4. The Ag point 4 and the Pt wire 5 are electrode leads.

[0051] The zinc oxide nanocage sensing electrode 2 and the reference electrode 3 are separate from each other and symmetrically arranged at both ends of the upper surface of the solid electrolyte 1, while the heating element 7 is arranged on the lower surface of the solid electrolyte 1.

[0052] The heating element 7 can be configured as a thin strip structure.

[0053] As a preferred embodiment of the present invention, the present invention also provides a method for preparing a nanocage-like zinc oxide electrode material, which includes the following steps:

[0054] Step S11: Synthesize ZIF-8 self-sacrificing template;

[0055] Specifically, the present invention also provides a method for preparing a ZIF-8 self-sacrificial template, which includes the following steps:

[0056] Step S111: Weigh zinc acetate, 2-methylimidazole and deionized water according to the stoichiometric ratio of 1:25-35:1600-1900;

[0057] Step S112: Dissolve zinc acetate and 2-methylimidazole in deionized water, mix and stir for 8-12 min, and then add hexadecyltrimethylammonium bromide (CTAB) to obtain a hydrothermal precursor solution;

[0058] The mass ratio of CTAB to zinc ions is 0 wt% ≤ CTAB / Zn ≤ 0.5 wt%.

[0059] Step S113: Pour the precursor solution into the polymerization reactor and place it at 100-140℃ for hydrothermal synthesis for 20-28 hours. Then filter, wash and dry the product to obtain ZIF-8 self-sacrificial template, the morphology of which is affected by the amount of CTAB added.

[0060] Step S12: Calcine the ZIF-8 self-sacrificing template in air to obtain nanocage-shaped zinc oxide electrode material.

[0061] It should be noted that the nanocage-like zinc oxide electrode material is prepared by calcining the ZIF-8 self-sacrificing template in air, specifically including:

[0062] ZIF-8 self-sacrificing templates are heated in a muffle furnace at a rate of 0.5-1.5℃ / min and calcined at a high temperature of 420-480℃ for 2.5-3.5 hours, and then ground to obtain cage-like zinc oxide powder.

[0063] As a preferred embodiment of the present invention, step S12 specifically includes calcining the synthesized ZIF-8 self-sacrificing template in air at 420-480°C for 2.5-3.5 hours to remove organic ligands and prepare nanocage-like zinc oxide electrode material.

[0064] This invention also provides a method for preparing a potential-type hydrogen sensor, which includes the following steps:

[0065] Step S21: Prepare reference electrode 3;

[0066] Specifically, the preparation of the reference electrode 3 includes the following steps:

[0067] The first raw material slurry is coated onto the solid electrolyte 1 and kept at 120-180℃ for 20-40 minutes to allow the organic solvent in the Pt slurry to evaporate completely. Then, the electrolyte substrate 1 is calcined at 800-1200℃ for 20-40 minutes to form the reference electrode 3.

[0068] The first raw material slurry is Pt slurry.

[0069] The preparation of the reference electrode 3 is described in detail below, including the following specific steps:

[0070] A reference electrode 3 with a diameter of approximately 2.2 mm and a thickness of 15 μm is formed on one end of the surface of a solid electrolyte 1 with a diameter of 12.5 mm and a thickness of 1 mm using the first raw material slurry. Then, the GDC electrolyte substrate is placed in an oven at 150 °C for 30 min to allow the organic solvent in the platinum slurry to evaporate completely. The solid electrolyte 1 is then calcined at 1000 °C for 30 min to form the reference electrode 3 on the solid electrolyte 1.

[0071] Step S22: Prepare nanocage-shaped zinc oxide electrode paste;

[0072] Specifically, the preparation of the nanocage-shaped zinc oxide electrode slurry includes the following steps:

[0073] Terpineol and ethyl cellulose are mixed at a mass ratio of 5-13:1 to obtain modified terpineol; nanocage-shaped zinc oxide electrode material is weighed, the modified terpineol is added dropwise, and then the mixture is thoroughly ground for 0.6-1.4 hours to obtain nanocage-shaped zinc oxide electrode slurry.

[0074] Step S23: Prepare zinc oxide nanocage sensitive electrode 2;

[0075] The zinc oxide nanocage sensitive electrode 2 is prepared by screen printing sensitive electrode paste onto solid electrolyte 1.

[0076] Specifically, the preparation of the zinc oxide nanocage sensitive electrode 2 includes the following steps:

[0077] The prepared nanocage-shaped zinc oxide electrode slurry is coated on the solid electrolyte 1, with the reference electrode 3 on the same side of the solid electrolyte 1. Then, it is placed at 120-180℃ for 20-40 minutes to allow the organic solvent in the electrode slurry to evaporate completely. The solid electrolyte 1 is then calcined at 550-650℃ for 2.5-3.5 hours to form the zinc oxide nanocage sensitive electrode 2.

[0078] Step S24: Attach two Pt wires to the middle positions of the reference electrode 3 and the zinc oxide nanocage sensitive electrode 2 respectively using dotted Ag paste as electrode leads;

[0079] Step S25: Assemble the lower surface of the solid electrolyte 1 and the ceramic plate 6 with the heating element 7 to obtain the device;

[0080] In a preferred embodiment of the present invention, step S25 includes attaching two Pt wires, each approximately 3 cm long, to the reference electrode 3 and the zinc oxide nanocage sensitive electrode 2 using Ag paste to draw electrode leads; then, using an inorganic adhesive (Al2O3 and water glass Na2SiO3·9H2O, prepared in a mass ratio of approximately 5:1), bonding the lower surface of the GDC substrate (the side without electrode coating) to an alumina ceramic plate (12.5 mm in diameter and 1 mm thick) of the same size with a Pt heating element; thus completing the fabrication of the potential-type hydrogen sensor, labeled as sensor Z1.

[0081] Step S26: The obtained device is welded and packaged to prepare a potential-type hydrogen sensor based on a nanocage-shaped zinc oxide electrode.

[0082] In a preferred embodiment of the present invention, prior to step S21, the method further includes: preparing a solid electrolyte, specifically including:

[0083] Step S201: Synthesize GDC (GDC: Ce) via citric acid-nitrate self-propagating combustion method. 0.8 Gd 0.2 O 1.9 )powder;

[0084] As a preferred embodiment of the present invention, the synthesis of GDC (GDC: Ce) via citric acid-nitrate self-propagating combustion method is described. 0.8 Gd 0.2 O 1.9 Powder, including:

[0085] Step S2011: First, weigh appropriate amounts of Ce(NO3)3·6H2O and Gd2O3 according to the stoichiometric ratio, dissolve them in a mixed solution of deionized water and nitric acid, stir evenly, and then add citric acid. The molar ratio of citric acid to metal ions is (0.8-1.6):(0.5-1.5), preferably 1.5:1, and the number of milliliters of nitric acid is equal to the number of grams of citric acid.

[0086] Step S2012: Then, the pH value of the solution is adjusted to 8-9 with NH3·H2O and stirred continuously for 10 hours. The stirred solution is placed on a 1000℃ adjustable universal electric furnace for high-temperature self-propagating combustion to form primary powder. The primary powder is then calcined at 1000℃ for 3 hours on a reference electrode to obtain GDC powder.

[0087] Step S202: GDC powder is ball-milled for 20-28 hours, then an appropriate amount of PVA solution is added and milled for 1.5-2.5 hours. Finally, 0.5-0.7g of powder is pressed into shape under 10MPa pressure and sintered at 1200-1800℃ for 8-12 hours to obtain a solid electrolyte. The heating and cooling rate is fixed at 2.5-3.5℃ / min.

[0088] Example 1

[0089] This invention also provides a method for preparing a nanocage-like zinc oxide electrode material, which includes the following steps:

[0090] Step S11: Synthesize ZIF-8 self-sacrificing template;

[0091] Specifically, the present invention also provides a method for preparing a ZIF-8 self-sacrificial template, which includes the following steps:

[0092] Step S111: Weigh zinc acetate, 2-methylimidazole and deionized water according to the stoichiometric ratio of 1:25:1900;

[0093] Step S112: Dissolve zinc acetate and 2-methylimidazole in deionized water, mix and stir for 12 min, and then add hexadecyltrimethylammonium bromide (CTAB) to obtain a hydrothermal precursor solution;

[0094] The mass ratio of CTAB to zinc ions is 0 wt% ≤ CTAB / Zn ≤ 0.5 wt%.

[0095] Step S113: Pour the precursor solution into the polymerization reactor and place it at 100-140℃ for hydrothermal synthesis for 20-28 hours. Then filter, wash and dry the product to obtain ZIF-8 self-sacrificial template, the morphology of which is affected by the amount of CTAB added.

[0096] Step S12: Calcine the ZIF-8 self-sacrificing template in air to obtain nanocage-shaped zinc oxide electrode material.

[0097] It should be noted that the nanocage-like zinc oxide electrode material is prepared by calcining the ZIF-8 self-sacrificing template in air, specifically including:

[0098] ZIF-8 self-sacrificing templates were heated in a muffle furnace at a rate of 1.5℃ / min and calcined at a high temperature of 480℃ for 3.5 hours, and then ground to obtain cage-like zinc oxide powder.

[0099] As a preferred embodiment of the present invention, step S12 specifically includes calcining the synthesized ZIF-8 self-sacrificing template in air at 480°C for 3.5 h to remove organic ligands and prepare nanocage-like zinc oxide electrode material.

[0100] This invention also provides a method for preparing a potential-type hydrogen sensor, which includes the following steps:

[0101] Step S21: Prepare reference electrode 3;

[0102] Specifically, the preparation of the reference electrode 3 includes the following steps:

[0103] The first raw material slurry is coated onto the solid electrolyte 1 and kept at 180°C for 40 minutes to allow the organic solvent in the Pt slurry to evaporate completely. Then, the electrolyte substrate 1 is calcined at 1200°C for 40 minutes to form the reference electrode 3.

[0104] The first raw material slurry is Pt slurry.

[0105] The preparation of the reference electrode 3 is described in detail below, including the following specific steps:

[0106] A reference electrode 3 with a diameter of approximately 2.2 mm and a thickness of 15 μm is formed on one end of the surface of a solid electrolyte 1 with a diameter of 12.5 mm and a thickness of 1 mm using the first raw material slurry. Then, the GDC electrolyte substrate is placed in an oven at 150 °C for 30 min to allow the organic solvent in the platinum slurry to evaporate completely. The solid electrolyte 1 is then calcined at 1000 °C for 30 min to form the reference electrode 3 on the solid electrolyte 1.

[0107] Step S22: Prepare nanocage-shaped zinc oxide electrode paste;

[0108] Specifically, the preparation of the nanocage-shaped zinc oxide electrode slurry includes the following steps:

[0109] Terpineol and ethyl cellulose were mixed at a mass ratio of 13:1 to obtain modified terpineol; nanocage-shaped zinc oxide electrode material was weighed, the modified terpineol was added dropwise, and then the mixture was ground thoroughly for 0.6-1.4 hours to obtain nanocage-shaped zinc oxide electrode slurry.

[0110] Step S23: Prepare zinc oxide nanocage sensitive electrode 2;

[0111] The zinc oxide nanocage sensitive electrode 2 is prepared by screen printing sensitive electrode paste onto solid electrolyte 1.

[0112] Specifically, the preparation of the zinc oxide nanocage sensitive electrode 2 includes the following steps:

[0113] The prepared nanocage-shaped zinc oxide electrode slurry was coated on the solid electrolyte 1, with the reference electrode 3 on the same side of the solid electrolyte 1. Then, it was placed at 180°C for 40 min to allow the organic solvent in the electrode slurry to evaporate completely. The solid electrolyte 1 was then calcined at 650°C for 3.5 h to form the zinc oxide nanocage sensitive electrode 2.

[0114] Step S24: Attach two Pt wires to the middle positions of the reference electrode 3 and the zinc oxide nanocage sensitive electrode 2 respectively using dotted Ag paste as electrode leads;

[0115] Step S25: Install the lower surface of the solid electrolyte 1 and the ceramic plate 6 with the heating element 7 together;

[0116] In a preferred embodiment of the present invention, step S25 includes attaching two Pt wires, each approximately 3 cm long, to the reference electrode 3 and the zinc oxide nanocage sensitive electrode 2 using Ag paste to draw electrode leads; then, using an inorganic adhesive (Al2O3 and water glass Na2SiO3·9H2O, prepared in a mass ratio of approximately 5:1), bonding the lower surface of the GDC substrate (the side without electrode coating) to an alumina ceramic plate (12.5 mm in diameter and 1 mm thick) of the same size with a Pt heating element; thus completing the fabrication of the potential-type hydrogen sensor, labeled as sensor Z1.

[0117] Step S26: The obtained device is welded and packaged to prepare a potential-type hydrogen sensor based on a nanocage-shaped zinc oxide electrode.

[0118] In a preferred embodiment of the present invention, prior to step S21, the method further includes: preparing a solid electrolyte, specifically including:

[0119] Step S201: Synthesize GDC (GDC: Ce) via citric acid-nitrate self-propagating combustion method. 0.8 Gd 0.2 O 1.9 )powder;

[0120] As a preferred embodiment of the present invention, the synthesis of GDC (GDC: Ce) via citric acid-nitrate self-propagating combustion method is described. 0.8 Gd 0.2 O 1.9 Powder, including:

[0121] Step S2011: First, weigh appropriate amounts of Ce(NO3)3·6H2O and Gd2O3 according to the stoichiometric ratio, dissolve them in a mixed solution of deionized water and nitric acid, stir evenly, and then add citric acid. The molar ratio of citric acid to metal ions is 1.6:1.5, and the number of milliliters of nitric acid is equal to the number of grams of citric acid.

[0122] Step S2012: Then, the pH value of the solution is adjusted to 8-9 with NH3·H2O and stirred continuously for 10 hours. The stirred solution is placed on a 1000℃ adjustable universal electric furnace for high-temperature self-propagating combustion to form primary powder. The primary powder is then calcined at 1000℃ for 3 hours on a reference electrode to obtain GDC powder.

[0123] Step S202: GDC powder is ball-milled for 28 hours, then an appropriate amount of PVA solution is added and milled for 2.5 hours. Finally, 0.7g of powder is pressed into shape under 10MPa pressure and sintered at 1800℃ for 12 hours to obtain solid electrolyte GDC. The heating and cooling rate is fixed at 3.5℃ / min for the reference electrode.

[0124] Example 2

[0125] This invention also provides a method for preparing a nanocage-like zinc oxide electrode material, which includes the following steps:

[0126] Step S11: Synthesize ZIF-8 self-sacrificing template;

[0127] Specifically, the present invention also provides a method for preparing a ZIF-8 self-sacrificial template, which includes the following steps:

[0128] Step S111: Weigh zinc acetate, 2-methylimidazole and deionized water according to the stoichiometric ratio of 1:35:1600;

[0129] Step S112: Dissolve zinc acetate and 2-methylimidazole in deionized water, mix and stir for 8 minutes, and then add hexadecyltrimethylammonium bromide (CTAB) to obtain a hydrothermal precursor solution;

[0130] The mass ratio of CTAB to zinc ions is 0 wt% ≤ CTAB / Zn ≤ 0.5 wt%.

[0131] Step S113: Pour the precursor solution into the polymerization reactor and place it at 100°C for hydrothermal synthesis for 20 hours. Then filter, wash and dry the product to obtain ZIF-8 self-sacrificial template, the morphology of which is affected by the amount of CTAB added.

[0132] Step S12: Calcine the ZIF-8 self-sacrificing template in air to obtain nanocage-shaped zinc oxide electrode material.

[0133] It should be noted that the nanocage-like zinc oxide electrode material is prepared by calcining the ZIF-8 self-sacrificing template in air, specifically including:

[0134] ZIF-8 self-sacrificing templates were heated in a muffle furnace at a rate of 0.5℃ / min and calcined at a high temperature of 420℃ for 2.5 hours, and then ground to obtain cage-like zinc oxide powder.

[0135] As a preferred embodiment of the present invention, step S12 specifically includes calcining the synthesized ZIF-8 self-sacrificing template in air at 420°C for 2.5 h to remove organic ligands and prepare nanocage-like zinc oxide electrode material.

[0136] This invention also provides a method for preparing a potential-type hydrogen sensor, which includes the following steps:

[0137] Step S21: Prepare reference electrode 3;

[0138] Specifically, the preparation of the reference electrode 3 includes the following steps:

[0139] The first raw material slurry is coated onto the solid electrolyte 1 and kept at 120°C for 20 minutes to allow the organic solvent in the Pt slurry to evaporate completely. Then, the electrolyte substrate 1 is calcined at 800°C for 20 minutes to form the reference electrode 3.

[0140] The first raw material slurry is Pt slurry.

[0141] The preparation of the reference electrode 3 is described in detail below, including the following specific steps:

[0142] A reference electrode 3 with a diameter of approximately 2.2 mm and a thickness of 15 μm is formed on one end of the surface of a solid electrolyte 1 with a diameter of 12.5 mm and a thickness of 1 mm using the first raw material slurry. Then, the GDC electrolyte substrate is placed in an oven at 150 °C for 30 min to allow the organic solvent in the platinum slurry to evaporate completely. The solid electrolyte 1 is then calcined at 1000 °C for 30 min to form the reference electrode 3 on the solid electrolyte 1.

[0143] Step S22: Prepare nanocage-shaped zinc oxide electrode paste;

[0144] Specifically, the preparation of the nanocage-shaped zinc oxide electrode slurry includes the following steps:

[0145] Terpineol and ethyl cellulose are mixed at a mass ratio of 5-13:1 to obtain modified terpineol; nanocage-shaped zinc oxide electrode material is weighed, the modified terpineol is added dropwise, and then the mixture is thoroughly ground for 0.6-1.4 hours to obtain nanocage-shaped zinc oxide electrode slurry.

[0146] Step S23: Prepare zinc oxide nanocage sensitive electrode 2;

[0147] The zinc oxide nanocage sensitive electrode 2 is prepared by screen printing sensitive electrode paste onto solid electrolyte 1.

[0148] Specifically, the preparation of the zinc oxide nanocage sensitive electrode 2 includes the following steps:

[0149] The prepared nanocage-shaped zinc oxide electrode slurry was coated on the solid electrolyte 1, with the reference electrode 3 on the same side of the solid electrolyte 1. Then, it was placed at 120°C for 20 min to allow the organic solvent in the electrode slurry to evaporate completely. The solid electrolyte 1 was then calcined at 550°C for 2.5 h to form the zinc oxide nanocage sensitive electrode 2.

[0150] Step S24: Attach two Pt wires to the middle positions of the reference electrode 3 and the zinc oxide nanocage sensitive electrode 2 respectively using dotted Ag paste as electrode leads;

[0151] Step S25: Install the lower surface of the solid electrolyte 1 and the ceramic plate 6 with the heating element 7 together;

[0152] In a preferred embodiment of the present invention, step S25 includes attaching two Pt wires, each approximately 3 cm long, to the reference electrode 3 and the zinc oxide nanocage sensitive electrode 2 using Ag paste to draw electrode leads; then, using an inorganic adhesive (Al2O3 and water glass Na2SiO3·9H2O, prepared in a mass ratio of approximately 5:1), bonding the lower surface of the GDC substrate (the side without electrode coating) to an alumina ceramic plate (12.5 mm in diameter and 1 mm thick) of the same size with a Pt heating element; thus completing the fabrication of the potential-type hydrogen sensor, labeled as sensor Z1.

[0153] Step S26: The obtained device is welded and packaged to prepare a potential-type hydrogen sensor based on a nanocage-shaped zinc oxide electrode.

[0154] In a preferred embodiment of the present invention, prior to step S21, the method further includes: preparing a solid electrolyte, specifically including:

[0155] Step S201: Synthesize GDC (GDC: Ce) via citric acid-nitrate self-propagating combustion method. 0.8 Gd 0.2 O 1.9 )powder;

[0156] As a preferred embodiment of the present invention, the synthesis of GDC (GDC: Ce) via citric acid-nitrate self-propagating combustion method is described. 0.8 Gd 0.2 O 1.9 Powder, including:

[0157] Step S2011: First, weigh appropriate amounts of Ce(NO3)3·6H2O and Gd2O3 according to the stoichiometric ratio, dissolve them in a mixed solution of deionized water and nitric acid, stir evenly, and then add citric acid. The molar ratio of citric acid to metal ions is 0.8:1.5, and the number of milliliters of nitric acid is equal to the number of grams of citric acid.

[0158] Step S2012: Then, the pH value of the solution is adjusted to 8-9 with NH3·H2O and stirred continuously for 10 hours. The stirred solution is placed on a 1000℃ adjustable universal electric furnace for high-temperature self-propagating combustion to form primary powder. The primary powder is then calcined at 1000℃ for 3 hours on a reference electrode to obtain GDC powder.

[0159] Step S202: GDC powder is ball-milled for 20-28 hours, then an appropriate amount of PVA solution is added and milled for 1.5 hours. Finally, 0.5g of powder is pressed into shape under 10MPa pressure and sintered at 1200℃ for 8 hours to obtain solid electrolyte GDC. The heating and cooling rate is fixed at 2.5℃ / min for the reference electrode.

[0160] Example 3

[0161] This invention also provides a method for preparing a nanocage-like zinc oxide electrode material, which includes the following steps:

[0162] Step S11: Synthesize ZIF-8 self-sacrificing template;

[0163] Specifically, the present invention also provides a method for preparing a ZIF-8 self-sacrificial template, which includes the following steps:

[0164] Step S111: Weigh zinc acetate, 2-methylimidazole and deionized water according to the stoichiometric ratio of 1:28:1850;

[0165] Step S112: Dissolve zinc acetate and 2-methylimidazole in deionized water, mix and stir for 11 min, and then add hexadecyltrimethylammonium bromide (CTAB) to obtain a hydrothermal precursor solution;

[0166] The mass ratio of CTAB to zinc ions is 0 wt% ≤ CTAB / Zn ≤ 0.5 wt%.

[0167] Step S113: Pour the precursor solution into the polymerization reactor and place it at 140℃ for hydrothermal synthesis for 26 hours. Then filter, wash and dry the product to obtain ZIF-8 self-sacrificial template, the morphology of which is affected by the amount of CTAB added.

[0168] Step S12: Calcine the ZIF-8 self-sacrificing template in air to obtain nanocage-shaped zinc oxide electrode material.

[0169] It should be noted that the nanocage-like zinc oxide electrode material is prepared by calcining the ZIF-8 self-sacrificing template in air, specifically including:

[0170] ZIF-8 self-sacrificing templates were heated in a muffle furnace at a rate of 1.2℃ / min and calcined at a high temperature of 460℃ for 3.2 hours, and then ground to obtain cage-like zinc oxide powder.

[0171] As a preferred embodiment of the present invention, step S12 specifically includes calcining the synthesized ZIF-8 self-sacrificing template in air at 460°C for 3.2 hours to remove organic ligands and prepare nanocage-like zinc oxide electrode material.

[0172] This invention also provides a method for preparing a potential-type hydrogen sensor, which includes the following steps:

[0173] Step S21: Prepare reference electrode 3;

[0174] Specifically, the preparation of the reference electrode 3 includes the following steps:

[0175] The first raw material slurry is coated onto the solid electrolyte 1 and kept at 160°C for 35 minutes to allow the organic solvent in the Pt slurry to evaporate completely. Then, the electrolyte substrate 1 is calcined at 1100°C for 25-35 minutes to form the reference electrode 3.

[0176] The first raw material slurry is Pt slurry.

[0177] The preparation of the reference electrode 3 is described in detail below, including the following specific steps:

[0178] A reference electrode 3 with a diameter of approximately 2.2 mm and a thickness of 15 μm is formed on one end of the surface of a solid electrolyte 1 with a diameter of 12.5 mm and a thickness of 1 mm using the first raw material slurry. Then, the GDC electrolyte substrate is placed in an oven at 150 °C for 30 min to allow the organic solvent in the platinum slurry to evaporate completely. The solid electrolyte 1 is then calcined at 1000 °C for 30 min to form the reference electrode 3 on the solid electrolyte 1.

[0179] Step S22: Prepare nanocage-shaped zinc oxide electrode paste;

[0180] Specifically, the preparation of the nanocage-shaped zinc oxide electrode slurry includes the following steps:

[0181] Terpineol and ethyl cellulose were mixed at a mass ratio of 7-11:1 to obtain modified terpineol; nanocage-shaped zinc oxide electrode material was weighed, the modified terpineol was added dropwise, and then the mixture was ground thoroughly for 0.8-1.2 hours to obtain nanocage-shaped zinc oxide electrode slurry.

[0182] Step S23: Prepare zinc oxide nanocage sensitive electrode 2;

[0183] The zinc oxide nanocage sensitive electrode 2 is prepared by screen printing sensitive electrode paste onto solid electrolyte 1.

[0184] Specifically, the preparation of the zinc oxide nanocage sensitive electrode 2 includes the following steps:

[0185] The prepared nanocage-shaped zinc oxide electrode slurry was coated on the solid electrolyte 1, with the reference electrode 3 on the same side of the solid electrolyte 1. Then, it was placed at 160°C for 40 min to allow the organic solvent in the electrode slurry to evaporate completely. The solid electrolyte 1 was then calcined at 620°C for 3.2 h to form the zinc oxide nanocage sensitive electrode 2.

[0186] Step S24: Attach two Pt wires to the middle positions of the reference electrode 3 and the zinc oxide nanocage sensitive electrode 2 respectively using dotted Ag paste as electrode leads;

[0187] Step S25: Install the lower surface of the solid electrolyte 1 and the ceramic plate 6 with the heating element 7 together;

[0188] In a preferred embodiment of the present invention, step S25 includes attaching two Pt wires, each approximately 3 cm long, to the reference electrode 3 and the zinc oxide nanocage sensitive electrode 2 using Ag paste to draw electrode leads; then, using an inorganic adhesive (Al2O3 and water glass Na2SiO3·9H2O, prepared in a mass ratio of approximately 5:1), bonding the lower surface of the GDC substrate (the side without electrode coating) to an alumina ceramic plate (12.5 mm in diameter and 1 mm thick) of the same size with a Pt heating element; thus completing the fabrication of the potential-type hydrogen sensor, labeled as sensor Z1.

[0189] Step S26: The obtained device is welded and packaged to prepare a potential-type hydrogen sensor based on a nanocage-shaped zinc oxide electrode.

[0190] In a preferred embodiment of the present invention, prior to step S21, the method further includes: preparing a solid electrolyte, specifically including:

[0191] Step S201: Synthesize GDC (GDC: Ce) via citric acid-nitrate self-propagating combustion method. 0.8 Gd 0.2 O 1.9 )powder;

[0192] As a preferred embodiment of the present invention, the synthesis of GDC (GDC: Ce) via citric acid-nitrate self-propagating combustion method is described. 0.8 Gd 0.2 O 1.9 Powder, including:

[0193] Step S2011: First, weigh appropriate amounts of Ce(NO3)3·6H2O and Gd2O3 according to the stoichiometric ratio, dissolve them in a mixed solution of deionized water and nitric acid, stir evenly, and then add citric acid. The molar ratio of citric acid to metal ions is 1.6:0.5, and the number of milliliters of nitric acid is equal to the number of grams of citric acid.

[0194] Step S2012: Then, the pH value of the solution is adjusted to 8-9 with NH3·H2O and stirred continuously for 10 hours. The stirred solution is placed on a 1000℃ adjustable universal electric furnace for high-temperature self-propagating combustion to form primary powder. The primary powder is then calcined at 1000℃ for 3 hours on a reference electrode to obtain GDC powder.

[0195] Step S202: GDC powder is ball-milled for 20-28 hours, then an appropriate amount of PVA solution is added and milled for 1.8-2.2 hours. Finally, 0.55-0.65g of powder is pressed into shape under 10MPa pressure and sintered at 1400-1600℃ for 9-11 hours to obtain solid electrolyte GDC. The heating and cooling rate is fixed at 2.8-3.2℃ / min for the reference electrode.

[0196] Example 4

[0197] This invention also provides a method for preparing a nanocage-like zinc oxide electrode material, which includes the following steps:

[0198] Step S11: Synthesize ZIF-8 self-sacrificing template;

[0199] Specifically, the present invention also provides a method for preparing a ZIF-8 self-sacrificial template, which includes the following steps:

[0200] Step S111: Weigh zinc acetate, 2-methylimidazole and deionized water according to the stoichiometric ratio of 1:32:1650;

[0201] Step S112: Dissolve zinc acetate and 2-methylimidazole in deionized water, mix and stir for 9 min, and then add hexadecyltrimethylammonium bromide (CTAB) to obtain a hydrothermal precursor solution;

[0202] The mass ratio of CTAB to zinc ions is 0 wt% ≤ CTAB / Zn ≤ 0.5 wt%.

[0203] Step S113: Pour the precursor solution into the polymerization reactor and place it at 100-140℃ for hydrothermal synthesis for 22 hours. Then filter, wash and dry the product to obtain ZIF-8 self-sacrificial template, the morphology of which is affected by the amount of CTAB added.

[0204] Step S12: Calcine the ZIF-8 self-sacrificing template in air to obtain nanocage-shaped zinc oxide electrode material.

[0205] It should be noted that the nanocage-like zinc oxide electrode material is prepared by calcining the ZIF-8 self-sacrificing template in air, specifically including:

[0206] ZIF-8 self-sacrificing templates were heated in a muffle furnace at a rate of 0.8℃ / min and calcined at a high temperature of 440℃ for 2.8 hours, and then ground to obtain cage-like zinc oxide powder.

[0207] As a preferred embodiment of the present invention, step S12 specifically includes calcining the synthesized ZIF-8 self-sacrificing template in air at 440°C for 2.8 hours to remove organic ligands and prepare nanocage-like zinc oxide electrode material.

[0208] This invention also provides a method for preparing a potential-type hydrogen sensor, which includes the following steps:

[0209] Step S21: Prepare reference electrode 3;

[0210] Specifically, the preparation of the reference electrode 3 includes the following steps:

[0211] The first raw material slurry is coated onto the solid electrolyte 1 and kept at 140°C for 25 minutes to allow the organic solvent in the Pt slurry to evaporate completely. Then, the electrolyte substrate 1 is calcined at 900°C for 25-35 minutes to form the reference electrode 3.

[0212] The first raw material slurry is Pt slurry.

[0213] The preparation of the reference electrode 3 is described in detail below, including the following specific steps:

[0214] A reference electrode 3 with a diameter of approximately 2.2 mm and a thickness of 15 μm is formed on one end of the surface of a solid electrolyte 1 with a diameter of 12.5 mm and a thickness of 1 mm using the first raw material slurry. Then, the GDC electrolyte substrate is placed in an oven at 150 °C for 30 min to allow the organic solvent in the platinum slurry to evaporate completely. The solid electrolyte 1 is then calcined at 1000 °C for 30 min to form the reference electrode 3 on the solid electrolyte 1.

[0215] Step S22: Prepare nanocage-shaped zinc oxide electrode paste;

[0216] Specifically, the preparation of the nanocage-shaped zinc oxide electrode slurry includes the following steps:

[0217] Terpineol and ethyl cellulose were mixed at a mass ratio of 7:1 to obtain modified terpineol; nanocage-shaped zinc oxide electrode material was weighed, the modified terpineol was added dropwise, and then the mixture was ground thoroughly for 0.8-1.2 hours to obtain nanocage-shaped zinc oxide electrode slurry.

[0218] Step S23: Prepare zinc oxide nanocage sensitive electrode 2;

[0219] The zinc oxide nanocage sensitive electrode 2 is prepared by screen printing sensitive electrode paste onto solid electrolyte 1.

[0220] Specifically, the preparation of the zinc oxide nanocage sensitive electrode 2 includes the following steps:

[0221] The prepared nanocage-shaped zinc oxide electrode slurry was coated on the solid electrolyte 1, with the reference electrode 3 on the same side of the solid electrolyte 1. Then, it was placed at 140°C for 20 min to allow the organic solvent in the electrode slurry to evaporate completely. The solid electrolyte 1 was then calcined at 580°C for 2.8 h to form the zinc oxide nanocage sensitive electrode 2.

[0222] Step S24: Attach two Pt wires to the middle positions of the reference electrode 3 and the zinc oxide nanocage sensitive electrode 2 respectively using dotted Ag paste as electrode leads;

[0223] Step S25: Install the lower surface of the solid electrolyte 1 and the ceramic plate 6 with the heating element 7 together;

[0224] In a preferred embodiment of the present invention, step S25 includes attaching two Pt wires, each approximately 3 cm long, to the reference electrode 3 and the zinc oxide nanocage sensitive electrode 2 using Ag paste to draw electrode leads; then, using an inorganic adhesive (Al2O3 and water glass Na2SiO3·9H2O, prepared in a mass ratio of approximately 5:1), bonding the lower surface of the GDC substrate (the side without electrode coating) to an alumina ceramic plate (12.5 mm in diameter and 1 mm thick) of the same size with a Pt heating element; thus completing the fabrication of the potential-type hydrogen sensor, labeled as sensor Z1.

[0225] Step S26: The obtained device is welded and packaged to prepare a potential-type hydrogen sensor based on a nanocage-shaped zinc oxide electrode.

[0226] In a preferred embodiment of the present invention, prior to step S21, the method further includes: preparing a solid electrolyte, specifically including:

[0227] Step S201: Synthesize GDC (GDC: Ce) via citric acid-nitrate self-propagating combustion method. 0.8 Gd 0.2 O 1.9 )powder;

[0228] As a preferred embodiment of the present invention, the synthesis of GDC (GDC: Ce) via citric acid-nitrate self-propagating combustion method is described. 0.8 Gd 0.2 O 1.9 Powder, including:

[0229] Step S2011: First, weigh appropriate amounts of Ce(NO3)3·6H2O and Gd2O3 according to the stoichiometric ratio, dissolve them in a mixed solution of deionized water and nitric acid, stir evenly, and then add citric acid. The molar ratio of citric acid to metal ions is 0.8:0.5, preferably 1.5:1, and the number of milliliters of nitric acid is equal to the number of grams of citric acid.

[0230] Step S2012: Then, the pH value of the solution is adjusted to 8-9 with NH3·H2O and stirred continuously for 10 hours. The stirred solution is placed on a 1000℃ adjustable universal electric furnace for high-temperature self-propagating combustion to form primary powder. The primary powder is then calcined at 1000℃ for 3 hours on a reference electrode to obtain GDC powder.

[0231] Step S202: GDC powder is ball-milled for 20-28 hours, then an appropriate amount of PVA solution is added and milled for 1.8-2.2 hours. Finally, 0.55-0.65g of powder is pressed into shape under 10MPa pressure and sintered at 1400-1600℃ for 9-11 hours to obtain solid electrolyte GDC. The heating and cooling rate is fixed at 2.8-3.2℃ / min for the reference electrode.

[0232] Example 5

[0233] As a preferred embodiment of the present invention, the present invention also provides a method for preparing a nanocage-like zinc oxide electrode material, which includes the following steps:

[0234] Step S11: Synthesize ZIF-8 self-sacrificing template;

[0235] Specifically, the present invention also provides a method for preparing a ZIF-8 self-sacrificial template, which includes the following steps:

[0236] Step S111: Weigh zinc acetate, 2-methylimidazole and deionized water according to the stoichiometric ratio of 1:30:1800;

[0237] Step S112: Dissolve zinc acetate and 2-methylimidazole in deionized water, mix and stir for 10 min, and then add hexadecyltrimethylammonium bromide (CTAB) to obtain a hydrothermal precursor solution;

[0238] The amount of CTAB added is 0 wt% of the mass ratio of zinc ions.

[0239] Step S113: Pour the precursor solution into the polymerization reactor and place it at 120°C for hydrothermal synthesis for 24 hours. Then filter, wash and dry the product to obtain ZIF-8 self-sacrificial template, the morphology of which is affected by the amount of CTAB added.

[0240] Step S12: Calcine the ZIF-8 self-sacrificing template in air to obtain nanocage-shaped zinc oxide electrode material.

[0241] It should be noted that the nanocage-like zinc oxide electrode material is prepared by calcining the ZIF-8 self-sacrificing template in air, specifically including:

[0242] ZIF-8 self-sacrificing templates were heated in a muffle furnace at a rate of 1°C / min and calcined at 450°C for 3 hours, and then ground to obtain cage-like zinc oxide powder.

[0243] As a preferred embodiment of the present invention, step S12 specifically includes calcining the synthesized ZIF-8 self-sacrificing template in air at 450°C for 3 hours to remove organic ligands and prepare nanocage-like zinc oxide electrode material.

[0244] This invention also provides a method for preparing a potential-type hydrogen sensor, which includes the following steps:

[0245] Step S21: Prepare reference electrode 3;

[0246] Specifically, the preparation of the reference electrode 3 includes the following steps:

[0247] The first raw material slurry is coated onto the solid electrolyte 1 and kept at 150°C for 30 minutes to allow the organic solvent in the Pt slurry to evaporate completely. Then, the electrolyte substrate 1 is calcined at 1000°C for 30 minutes to form the reference electrode 3.

[0248] The first raw material slurry is Pt slurry.

[0249] The preparation of the reference electrode 3 is described in detail below, including the following specific steps:

[0250] A reference electrode 3 with a diameter of approximately 2.2 mm and a thickness of 15 μm is formed on one end of the surface of a solid electrolyte 1 with a diameter of 12.5 mm and a thickness of 1 mm using the first raw material slurry. Then, the GDC electrolyte substrate is placed in an oven at 150 °C for 30 min to allow the organic solvent in the platinum slurry to evaporate completely. The solid electrolyte 1 is then calcined at 1000 °C for 30 min to form the reference electrode 3 on the solid electrolyte 1.

[0251] Step S22: Prepare nanocage-shaped zinc oxide electrode paste;

[0252] Specifically, the preparation of the nanocage-shaped zinc oxide electrode slurry includes the following steps:

[0253] Terpineol and ethyl cellulose were mixed at a mass ratio of 9:1 to obtain modified terpineol; nanocage-shaped zinc oxide electrode material was weighed, the modified terpineol was added dropwise, and then the mixture was ground thoroughly for 1 hour to obtain nanocage-shaped zinc oxide electrode slurry.

[0254] Step S23: Prepare zinc oxide nanocage sensitive electrode 2;

[0255] The zinc oxide nanocage sensitive electrode 2 is prepared by screen printing sensitive electrode paste onto solid electrolyte 1.

[0256] Specifically, the preparation of the zinc oxide nanocage sensitive electrode 2 includes the following steps:

[0257] The prepared nanocage-shaped zinc oxide electrode slurry was coated on the solid electrolyte 1, with the reference electrode 3 on the same side of the solid electrolyte 1. Then, it was placed at 150°C for 30 minutes to allow the organic solvent in the electrode slurry to evaporate completely. The solid electrolyte 1 was then calcined at 600°C for 3 hours to form the zinc oxide nanocage sensitive electrode 2.

[0258] Step S24: Attach two Pt wires to the middle positions of the reference electrode 3 and the zinc oxide nanocage sensitive electrode 2 respectively using dotted Ag paste as electrode leads;

[0259] Step S25: Install the lower surface of the solid electrolyte 1 and the ceramic plate 6 with the heating element 7 together;

[0260] In a preferred embodiment of the present invention, step S25 includes attaching two Pt wires, each approximately 3 cm long, to the reference electrode 3 and the zinc oxide nanocage sensitive electrode 2 using Ag paste to draw electrode leads; then, using an inorganic adhesive (Al2O3 and water glass Na2SiO3·9H2O, prepared in a mass ratio of approximately 5:1), bonding the lower surface of the GDC substrate (the side without electrode coating) to an alumina ceramic plate (12.5 mm in diameter and 1 mm thick) of the same size with a Pt heating element; thus completing the fabrication of the potential-type hydrogen sensor, labeled as sensor Z1.

[0261] Step S26: The obtained device is welded and packaged to prepare a potential-type hydrogen sensor based on a nanocage-shaped zinc oxide electrode.

[0262] In a preferred embodiment of the present invention, prior to step S21, the method further includes: preparing a solid electrolyte, specifically including:

[0263] Step S201: Synthesize GDC (GDC: Ce) via citric acid-nitrate self-propagating combustion method. 0.8 Gd 0.2 O 1.9 )powder;

[0264] As a preferred embodiment of the present invention, the synthesis of GDC (GDC: Ce) via citric acid-nitrate self-propagating combustion method is described. 0.8 Gd 0.2 O 1.9 Powder, including:

[0265] Step S2011: First, weigh appropriate amounts of Ce(NO3)3·6H2O and Gd2O3 according to the stoichiometric ratio, dissolve them in a mixed solution of deionized water and nitric acid, stir evenly, and then add citric acid. The molar ratio of citric acid to metal ions is 1.5:1, and the number of milliliters of nitric acid is equal to the number of grams of citric acid.

[0266] Step S2012: Then, the pH value of the solution is adjusted to 8-9 with NH3·H2O and stirred continuously for 10 hours. The stirred solution is placed on a 1000℃ adjustable universal electric furnace for high-temperature self-propagating combustion to form primary powder. The primary powder is then calcined at 1000℃ for 3 hours on a reference electrode to obtain GDC powder.

[0267] Step S202: GDC powder is ball-milled for 24 hours, then an appropriate amount of PVA solution is added and milled for 2 hours. Finally, 0.6g of powder is pressed into shape under 10MPa pressure and sintered at 1500℃ for 10 hours to obtain solid electrolyte GDC. The heating and cooling rate is fixed at 3℃ / min for the reference electrode.

[0268] Example 6

[0269] A potential-type hydrogen sensor was fabricated using nanocage-shaped zinc oxide synthesized hydrothermally with the addition of 0.16 wt% CTAB as the sensitive electrode material. The fabrication process was as follows: 0.16 wt% CTAB was added while stirring the mixed solution. The product after hydrothermal synthesis was filtered, washed, and dried to obtain zeolite imidazole framework-8, named ZIF-8-2. The temperature was increased at 1 °C / min in a muffle furnace and calcined at 450 °C for 3 hours. The resulting cage-shaped zinc oxide powder was then ground. The other fabrication steps in this embodiment were the same as in Example 5.

[0270] Example 7

[0271] A hybrid potential sensor was fabricated using nanocage-shaped zinc oxide synthesized hydrothermally with the addition of 0.35 wt% CTAB as the sensitive electrode material. The fabrication process was as follows: 0.35 wt% CTAB was added while stirring the mixed solution. The product after hydrothermal synthesis was filtered, washed, and dried to obtain zeolite imidazole framework-8, denoted as ZIF-8-3. The mixture was then calcined in a muffle furnace at a temperature of 450°C for 3 hours with a heating rate of 1°C / min, and the resulting cage-shaped zinc oxide powder was obtained by grinding. The other fabrication steps in this embodiment were the same as in Example 5.

[0272] It should be noted that, in order to illustrate the advantages of using nanocage-shaped zinc oxide as a sensitive electrode in this invention, a potential-type hydrogen sensor under the same conditions was prepared for comparison using conventional zinc oxide nanoparticles (the sensitive electrode powder is named ZnO-0) as the sensitive electrode (the sensor is named Z0).

[0273] The performance of the fabricated sensor was tested using traditional static testing methods. A data acquisition instrument was used to measure the electromotive force between the sensor's sensitive electrode and reference electrode. The sensor's output potential was synchronously recorded via a connection between the data acquisition instrument and a computer. The zinc oxide sensitive electrode of the sensor was connected to the positive terminal of the data acquisition instrument, and the Pt reference electrode was connected to the negative terminal. A constant voltage was applied across the heating element using a DC power supply (Wanptrk GPS3010D). By adjusting the power supply voltage, the temperature of the heating element was changed, thus placing the gas sensor at different operating temperatures. The actual temperature of the sensor was measured by multiple thermocouples.

[0274] Specific test results are as follows: Figure 2 , Figure 3 , Figure 4 and Figure 5 .in:

[0275] like Figure 2 As shown, by comparing with the standard card, it was found that the sensitive electrode material prepared by the present invention is a single-phase hexagonal wurtzite structure zinc oxide (JCPDS No.: 36-1451);

[0276] like Figure 3 As shown, when CTAB is added at a mass ratio of 0 wt% ( Figure 3 b) 0.16wt% Figure 3 c) and 0.35 wt% ( Figure 3 In step d), the prepared zinc oxide nanocages were all nanocage-like structures, and the size of individual zinc oxide nanocages gradually decreased with increasing CTAB addition, reaching 609 nm, 472 nm, and 390 nm, respectively. On the other hand, pore size analysis showed that increasing CTAB addition led to an increase in the pore size on the outer wall of the nanocages, reaching 26.4 nm, 27.2 nm, and 32.8 nm, respectively. These results indicate that zinc oxide nanocages were successfully derived using ZIF-8 as a self-sacrificing template, and their morphology can be controlled by changing the amount of CTAB added. For comparison, Figure 3 Figure a shows the morphology of conventional zinc oxide nanoparticles. It can be seen that the zinc oxide nanoparticles are tightly aggregated particles with a particle size of less than 100 nm, low porosity, and an average pore size of 24.2 nm, which is smaller than that of zinc oxide nanocages.

[0277] Figure 4 The dynamic response recovery curves of a potential-type hydrogen sensor based on three nanocage-shaped zinc oxide sensing electrodes and a conventional zinc oxide nanoparticle sensing electrode (used as a comparison) at 450 °C to different concentrations of hydrogen.

[0278] Among them, Z0 is a sensor using nano-particle zinc oxide as the sensitive electrode in the existing technology, and Z1-Z3 are sensors using nano-cage-shaped zinc oxide as the sensitive electrode.

[0279] Wherein: Z1 corresponds to Example 5 (0wt% CTAB);

[0280] Z2 corresponds to Example 6 (0.16wt% CTAB);

[0281] Z3 corresponds to Example 7 (0.35wt% CTAB).

[0282] like Figure 5 As shown, the response values ​​of sensors Z0-Z3 to hydrogen are linearly related to the logarithm of the concentration. Within the hydrogen concentration range of 20-500 ppm, the response values ​​follow the order Z3 > Z2 > Z1 > Z0. Z1, Z2, and Z3 still exhibit relatively high response values ​​for the lower hydrogen concentration of 20 ppm, at -17.0 mV, -23.0 mV, and -60.9 mV respectively, all significantly higher than the -5.3 mV of Z0 (the sensor corresponding to nano-particle zinc oxide). The response value of sensor Z3 to 20 ppm hydrogen is 11.6 times that of sensor Z0. This demonstrates that the nano-cage-like zinc oxide sensitive electrode significantly improves the response value and sensitivity to hydrogen, and that adjusting the CTAB can achieve even better results.

[0283] The present invention also provides a comparative experimental effect of Example 7 with the prior art reported on the planar potential type hydrogen sensor.

[0284] Table 1.

[0285]

[0286]

[0287] The relevant literature includes the following:

[0288] [1] Characteristics and modeling of solid-state hydrogen sensors, Journal of the Electrochemical Society, 141(1994)461.

[0289] [2] Hybrid potential hydrogen sensor based on zinc tungstate sensitive electrode, Sensors & Actuators B: Chemistry, 195(2014)520-525.

[0290] [3] Hydrogen sensing function of manganese tungstate / yttrium stabilized zirconium oxide / platinum hybrid potential sensor, Sensors & Actuators B: Chemistry, 206(2015)176-180.

[0291] [4] Potential hydrogen sensor based on yttrium-stabilized zirconium oxide electrolyte and cadmium tungstate interface, Sensors & Actuators B: Chemistry, 223(2016)365-371.

[0292] [5] Hybrid potential sensor based on cobalt tungstate compound sensing electrode for hydrogen detection, Research Progress of Royal Society of Chemistry, 7(2017)2919-2925.

[0293] [6] Development and testing of a prototype miniature hydrogen safety sensor, Sensors & Actuators B: Chemistry, 148(2010)469-477.

[0294] [7] Improving the hydrogen sensing performance of yttrium-stabilized zirconia-based electrochemical gas sensors by applying gold mesh and yttrium-stabilized zirconia coating, Sensors & Actuators B: Chemistry, 182(2013)40-44.

[0295] [8] A fast-response, high-sensitivity and high-selectivity mixed-potential hydrogen sensor based on strontium and iron-doped lanthanum chromate perovskite sensitive electrode, ACS Applied Materials & Interfaces, 9(2017)17219-17226.

[0296] [9] A high-performance potentiometric hydrogen sensor based on a hierarchical porous hollow tin oxide nanofiber sensitive electrode, Sensors & Actuators B: Chemistry, 268(2018)456-464.

[0297]

[10] Potentially-driven hydrogen sensing of ordered tin oxide thin films, Sensors & Actuators B: Chemistry, 321(2020)128505.

[0298]

[11] Electrochemical response of hybrid conductive perovskite enables low-cost and high-efficiency hydrogen sensing, Sensors & Actuators B: Chemistry, 14(2022)33580-33588.

[0299]

[12] Relationship between mixed potential hydrogen response and electrochemical activity of perovskite oxides, Sensors & Actuators B: Chemistry, 352 (2022).

[0300] As can be clearly seen from Table 1, compared with the previously reported planar potential hydrogen sensors, the Z3 sensor in this invention exhibits significantly higher response values ​​and sensitivity to hydrogen, and is more advantageous in detecting low concentrations of hydrogen.

[0301] Compared to conventional potentiometric hydrogen sensors based on zinc oxide nanoparticles as the sensitive electrode, this invention, using zinc oxide nanocages as the sensitive electrode, significantly improves the response value to hydrogen, increasing the response value to 20 ppm hydrogen by 11.6 times (see examples for details). Compared to the most advanced existing potentiometric hydrogen sensors, this invention also exhibits a significantly higher response, offering greater advantages in low-concentration hydrogen detection. The morphology of the zinc oxide nanocage sensitive electrode in this invention is highly tunable; by changing the amount of CTAB added, the morphology of the sensitive electrode can be easily controlled, improving the sensitivity to hydrogen and achieving high response and high sensitivity detection of hydrogen in a simple and effective way. The potentiometric hydrogen sensor involved in this invention has a planar structure, with main components including only a sensitive electrode, a reference electrode, a solid electrolyte, and a ceramic heating plate. Its structure is simple, its manufacturing process is easy, and it is easy to miniaturize and integrate, which is beneficial for mass production and practical applications.

[0302] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention.

Claims

1. A potentiometric hydrogen sensor, characterized in that, include: The system comprises a zinc oxide nanocage sensitive electrode, a reference electrode, a solid electrolyte, and a ceramic plate with a heating element for heating the solid electrolyte, the sensitive electrode, and the reference electrode; the solid electrolyte is mounted on the ceramic plate, and the zinc oxide nanocage sensitive electrode and the reference electrode are located on the surface of the solid electrolyte; the zinc oxide nanocage sensitive electrode is made of a nanocage-shaped zinc oxide electrode material. The preparation method of the nanocage-like zinc oxide electrode material includes the following steps: Step S11: Synthesize ZIF-8 self-sacrificing template; Step S12: Calcine the ZIF-8 self-sacrificing template in air to obtain nanocage-shaped zinc oxide electrode material; The method for preparing the ZIF-8 self-sacrificing template includes the following steps: Step S111: Weigh zinc acetate, 2-methylimidazole, and deionized water according to a stoichiometric ratio of 1:25-35:1600-1900; Step S112: Dissolve zinc acetate and 2-methylimidazole in deionized water, mix and stir for 8-12 min, and then add hexadecyltrimethylammonium bromide (CTAB) to obtain a hydrothermal precursor solution; Step S113: Pour the precursor solution into the polymerization reactor and place it at 100-140℃ for hydrothermal synthesis for 20-28 hours. Then filter, wash and dry the product to obtain ZIF-8 self-sacrificing template.

2. The potentiometric hydrogen sensor according to claim 1, characterized in that, The solid electrolyte is bonded to the ceramic plate with an adhesive.

3. A method for preparing a potentiometric hydrogen sensor as described in claim 1 or 2, characterized in that, Includes the following steps: Step S21: Prepare the reference electrode; Step S22: Prepare nanocage-shaped zinc oxide electrode paste; Step S23: Prepare zinc oxide nanocage sensitive electrode; Step S24: Attach two Pt wires to the middle of the reference electrode and the zinc oxide nanocage sensitive electrode respectively using dotted Ag paste to serve as electrode leads; Step S25: Assemble the lower surface of the solid electrolyte and the ceramic plate with the heating element to obtain the device; Step S26: Solder and package the obtained device to obtain a potential-type hydrogen sensor.

4. The method for preparing a potential-type hydrogen sensor according to claim 3, characterized in that, Before step S21, the method further includes: preparing a solid electrolyte, specifically including: GDC powder was synthesized via a citric acid-nitrate self-propagating combustion method. GDC powder was ball-milled for 20-28 hours, then an appropriate amount of PVA solution was added and milled for 1.5-2.5 hours. Finally, 0.5-0.7 g of powder was pressed into shape under 10 MPa pressure and sintered at 1200-1800 ℃ for 8-12 hours to obtain a solid electrolyte.

5. The method for preparing a potential-type hydrogen sensor according to claim 4, characterized in that, The mass ratio of CTAB to zinc ions is 0wt%≤CTAB / Zn≤0.5wt%.

6. The method for preparing a potential-type hydrogen sensor according to claim 3, characterized in that, The preparation of the reference electrode includes the following steps: The first raw material slurry is coated on the solid electrolyte (1) and kept at 120-180℃ for 20-40 minutes to allow the organic solvent in the Pt slurry to evaporate completely. Then the electrolyte substrate is calcined at 800-1200℃ for 20-40 minutes to form a reference electrode.

7. The method for preparing a potential-type hydrogen sensor according to claim 3, characterized in that, The preparation of the nanocage-shaped zinc oxide electrode slurry includes the following steps: Terpineol and ethyl cellulose are mixed at a mass ratio of 5-13:1 to obtain modified terpineol; nanocage-shaped zinc oxide electrode material is weighed, the modified terpineol is added dropwise, and then the mixture is thoroughly ground for 0.6-1.4 hours to obtain nanocage-shaped zinc oxide electrode slurry.

8. The method for preparing a potential-type hydrogen sensor according to claim 3, characterized in that, The preparation of the zinc oxide nanocage sensitive electrode includes the following steps: The prepared nanocage-shaped zinc oxide electrode slurry is coated on the solid electrolyte (1) and the reference electrode (3) is on the same side of the solid electrolyte (1). Then it is placed at 120-180℃ for 20-40 min to allow the organic solvent in the electrode slurry to evaporate completely. Then the solid electrolyte (1) is calcined at 550-650℃ for 2.5-3.5 h to form a zinc oxide nanocage sensitive electrode.

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