Porous titanium black ceramic body, preparation method and application thereof and electro-catalysis device

Abstract

The invention provides a porous titanium black ceramic body, a preparation method and application thereof and an electro-catalysis device. The preparation method comprises the following steps: carrying out sintering molding on a mixture of TiOx powder and a metal oxide type ionic crystal or firstly molding and then sintering to prepare a ceramic body containing the TiOx powder and the metal oxide type ionic crystal; carrying out acid pickling on the ceramic body to obtain a porous TiOx ceramic body; in the TiOx powder, x is more than 0 and less than or equal to 1; or carrying out sintering molding on the mixture of the TiO2 powder and the metal Mg, or firstly molding and then sintering to prepare a ceramic body containing the TiOx powder and the magnesium oxide; carrying out acid pickling on the ceramic body to obtain a porous TiOx ceramic body; in the TiOx powder, xlt is greater than or equal to 1; 2. The porous titanium black ceramic body has conductivity close to metal grade, a through porous structure and full-ceramic chemical stability, the preparation method is simple, the cost is low, and industrial production is facilitated.

Description

Technical Field

[0001] The invention relates to a porous titanium suboxide ceramic body, a preparation method thereof, an application thereof and an electrocatalytic device. Background Art

[0002] In the field of energy catalysis and electrochemical conversion, the development of high-performance catalyst supports consistently faces the triple challenges of electrical conductivity, porous structure, and chemical stability. While metal foams such as nickel and copper foams possess excellent metallic-grade conductivity, their limited surface area severely limits the density of active sites. Furthermore, their surface easily oxidizes in electrochemical environments, forming an insulating layer, leading to diminished catalytic activity and shortened lifetime. Carbon-based supports such as carbon paper or graphene, while possessing a rich porous structure, suffer from wide conductivity fluctuations and insufficient chemical stability. They are susceptible to corrosion and carbon loss at strong oxidation / reduction potentials, leading to structural collapse. Ceramic oxides such as TiO2 and SnO2 offer excellent corrosion resistance, but their semiconducting properties result in extremely low intrinsic conductivity, creating a bottleneck for electron transport. Although titanium oxides are considered a potential solution due to their moderate electrical conductivity and corrosion resistance, their industrial application is hampered by traditional preparation processes: powder sintering methods result in insufficient porosity due to high-temperature densification, while template-based pore-forming methods suffer from residual carbon impurities that clog pores and degrade conductivity. Multi-step reduction processes are characterized by high energy consumption and poor batch stability.

[0003] In recent years, the dealloying method has been attempted to construct porous titanium-based supports, but it faces fundamental limitations. Taking titanium-copper, titanium-nickel and other alloy systems as an example, the metal impurities remaining after pickling to remove the second component will poison the catalytic active sites. In addition, the conductivity of existing titanium oxide materials is still several orders of magnitude lower than that of metal supports, making it difficult to meet the needs of high current density electrocatalysis. Therefore, developing a support that combines metal-grade conductivity, a through-porous structure and all-ceramic chemical stability, and realizing a low-cost, scalable preparation process, is an urgent problem to be solved. Summary of the Invention

[0004] The technical problem solved by the present invention is to overcome the existing technical drawbacks of the inability to obtain titanyl ceramic materials with high conductivity, porous structure, and high chemical stability. The present invention provides a porous titania ceramic body, its preparation method, application, and electrocatalytic device. The porous titania ceramic body prepared by the present invention can be used as a highly active self-supporting catalyst support, exhibiting near-metallic-grade conductivity, a continuous porous structure, and full ceramic chemical stability. Furthermore, the preparation method is simple, cost-effective, and amenable to industrial production.

[0005] The present invention adopts TiO xUsing TiO2 powder and metal oxide ionic crystals as raw materials, or TiO2 powder and metallic Mg as raw materials, a mixed material ceramic body is prepared through sintering and molding. The metal oxide ionic crystals or magnesium oxide are then removed by acid washing to produce a titanium oxide ceramic body with a porous structure and high electrical conductivity. This method can achieve the preparation of a through-hole porous structure and avoid the residual metal impurities that poison the active sites in traditional alloy system dealloying preparation methods.

[0006] The present invention solves the above technical problems through the following technical solutions:

[0007] The present invention provides a method for preparing a porous titanium oxide ceramic body, comprising the following steps:

[0008] Method 1: (1) TiO x The mixture of powder and metal oxide type ionic crystal is sintered or formed first and then sintered to prepare a TiO x and ceramic bodies of metal oxide type ionic crystals;

[0009] (2) The TiO x The ceramic body of the metal oxide type ionic crystal is acid washed to obtain porous TiO x Ceramic body; wherein the TiO x In the case of 0<x≤1,

[0010] Method 2: (1) Sintering a mixture of TiO2 powder and metal Mg into a mold or forming the mixture first and then sintering the mixture to prepare a TiO2 powder. x and a ceramic body of magnesium oxide;

[0011] (2) The TiO x The ceramic body of magnesium oxide was acid washed to obtain porous TiO x Ceramic body; wherein the TiO x In the equation, 1≤x<2.

[0012] In method 1, the TiO x The powder can be prepared by yourself or purchased. x , x may be 0.05, 0.1, 0.2, 0.25, 0.3, 0.33, 0.35, 0.4, 0.45, 0.5, 0.6 or 1.0.

[0013] In method 1, when x is 0.5, the TiO x The preparation method of the powder may include the following steps: tableting and calcining a mixture of TiO and Ti to obtain TiO 0.5 powder.

[0014] The molar ratio of the TiO to the Ti may be 0.45:(0.50-0.60), for example, 0.45:0.52, 0.45:0.55 or 0.45:0.56.

[0015] The method for preparing the mixture of TiO and Ti preferably comprises the following steps: grinding TiO and Ti uniformly.

[0016] The grinding method can be conventional in the art, such as manual grinding or ball milling. The grinding time can be conventional in the art, generally 5-30 minutes, such as 10 minutes, 20 minutes or 30 minutes.

[0017] Wherein, the equipment for tableting can be conventional in this field, such as a tablet press. The pressure of the tableting can be 500-1000Mpa, such as 600Mpa, 700Mpa, 780Mpa or 850Mpa. The pressure of the tableting is preferably 3000-5000kg, such as 3500kg, 4000kg or 4500kg. During the tableting process, the holding time can be 10-30s, such as 15s, 20s or 25s. The diameter of the die for tableting can be 4-10mm.

[0018] The calcination environment is generally vacuum (≤10 -3 Pa) or inert atmosphere.

[0019] After the tableting, the pressed tablets are preferably placed in a reaction tube, and the reaction tube is evacuated and sealed before the calcination is performed.

[0020] The reaction tube is preferably a quartz tube. After the vacuum is drawn, the vacuum degree of the reaction tube is preferably less than or equal to 10 -3 The sealing is generally performed by heating and melting the nozzle of the reaction tube.

[0021] The calcination is generally carried out in a muffle furnace.

[0022] The rate of heating to the calcination temperature may be 3-10° C. / min, for example, 5° C. / min.

[0023] The calcination temperature is preferably 600-1100°C, such as 700°C, 750°C, 800°C, 900°C or 1000°C.

[0024] The calcination time is preferably 24-84 hours, such as 48 hours, 60 hours, 72 hours or 80 hours.

[0025] After the calcination, preferably, the flake sample is further ground.

[0026] In method 1, the metal oxide type ionic crystal is preferably one or more of alkali metal oxide, alkaline earth metal oxide, rare earth metal oxide and boron group metal oxide. The particle size of the metal oxide type ionic crystal can be adjusted according to the actual requirements of the target product porous TiO x The pore size of the ceramic body needs to be selected, preferably 10-600 nm, such as 20 nm, 30 nm, 40 nm, 50 nm, 80 nm, 100 nm, 150 nm, 200 nm, 300 nm or 500 nm, more preferably 10-200 nm.

[0027] Wherein, the alkali metal oxide may be sodium oxide and / or potassium oxide.

[0028] The alkaline earth metal oxide may be one or more of magnesium oxide, calcium oxide, barium oxide and strontium oxide.

[0029] The rare earth metal oxide may be one or more of La2O3, Ce2O3, Pr2O3, Nd2O3, Sm2O3, Eu2O3, Gd2O3, Tb2O3, Dy2O3, Ho2O3, Yb2O3, Er2O3 and Lu2O3.

[0030] The boron group metal oxide may be one or more of aluminum oxide, gallium oxide and indium oxide.

[0031] In method 1, the TiO x The molar ratio of the powder and the metal oxide type ionic crystal can be adjusted according to the actual conditions of the target product porous TiO x The pore size of the ceramic body can be selected by yourself. x The molar ratio of the powder to the metal oxide type ionic crystal is preferably 1:(1.0-3.5), for example 1:1.1, 1:1.2, 1:1.3, 1:1.5, 1:1.6, 1:1.8, 1:2.0 or 1:2.5.

[0032] In method 1, the TiO x The preparation method of the mixture of powder and metal oxide type ionic crystal preferably comprises the following steps: x The powder and the metal oxide type ionic crystal are ground uniformly, dispersed in a solvent, and ultrasonically treated, and then dried and ground.

[0033] The grinding method can be conventional in the art, generally manual grinding. The grinding time can be 10-30 minutes, for example 20 minutes.

[0034] The type of the solvent can be conventional in the art, such as anhydrous ethanol. The amount of the solvent can be conventional in the art, and the TiO x The ratio of the sum of the mass of the powder and the metal oxide type ionic crystal to the volume of the solvent may be (0.05-0.2) g / mL, for example 0.1 g / mL.

[0035] The ultrasonic treatment time may be conventional in the art, generally 10-60 min, such as 20 min, 30 min, 40 min or 50 min.

[0036] In method 1 and / or method 2, the sintering is preferably performed by spark plasma sintering, and the sintering is preferably performed in a spark plasma furnace.

[0037] When the spark plasma sintering method is used, the pressure during the sintering process may be 25-50 MPa, such as 30 MPa, 35 MPa or 40 MPa.

[0038] In method 1 and / or method 2, the rate of heating to the sintering temperature may be 40-110° C. / min, for example, 50° C. / min, 80° C. / min or 100° C. / min.

[0039] In method 1 and / or method 2, the sintering is generally performed in a vacuum or in an inert atmosphere. The sintering temperature may be 1000-1600°C, for example, 1200°C, 1300°C, or 1500°C. The sintering time may be 10-30 minutes, for example, 15 minutes.

[0040] In method 1, when the sintering molding method is adopted, in a preferred embodiment, the TiO x The mixture of the powder and the metal oxide ionic crystal is first heated to 1300°C at a rate of 100°C / min, and then continued to be heated to 1500°C at a rate of 50°C / min and kept at this temperature for 15 minutes.

[0041] In method 1, when the sintering molding method is adopted, in a more preferred embodiment, the TiO x The mixture of the powder and the metal oxide ionic crystal is first heated to 1300°C at a rate of 100°C / min, and then continued to be heated to 1500°C at a rate of 50°C / min and kept at this temperature for 15 minutes.

[0042] In method one and / or method two, when the method of first forming and then sintering is adopted: the forming method and the equipment used can be conventional in the field, such as tableting in a tablet press; the equipment used for sintering can be conventional in the field, such as in a tubular furnace or in a spark plasma furnace; the sintering is generally carried out in a vacuum or in an inert atmosphere; the rate of heating to the temperature of the sintering forming can be 40-110℃ / min, such as 50℃ / min, 80℃ / min or 100℃ / min; the sintering temperature can be 1000-1600℃, such as 1200℃, 1300℃, 1500℃ or 1550℃; the sintering time can be 10min-5h, such as 15min, 30min, 1h, 2h or 4.5h.

[0043] In method one and / or method two, the acid used in the pickling may be one or a combination of sulfuric acid, hydrochloric acid and phosphoric acid. The concentration of the acid used in the pickling may be 0.05-5M, for example, 0.2M, 0.5M, 1.5M or 2.0. The pickling time may be 20-100h, for example, 24h, 25h, 30h, 48h, 60h or 96h. The amount of acid used in the pickling process may be conventional in the art, generally sufficient to immerse the ceramic body. During the pickling process, preferably, the acid solution is changed every 10-16h.

[0044] In the second method, the TiO2 powder can be prepared by oneself or purchased. The particle size of the metal Mg can be selected according to the actual pore size requirements of the target product porous TiOx ceramic body, preferably 10-200nm, such as 20nm, 30nm, 50nm, 80nm or 100nm. The molar ratio of the TiO2 powder to the metal Mg can be selected according to the actual pore size requirements of the target product porous TiOx ceramic body. x The pore size of the ceramic body can be selected as desired. The molar ratio of the TiO2 powder to the metallic Mg is preferably 1:(1.0-3.5), such as 1:1.1, 1:1.2, 1:1.3, 1:1.5, 1:1.6, 1:1.8, 1:2.0, or 1:2.5.

[0045] In method two, the preparation method of the mixture of TiO2 powder and metal Mg may include the following steps: grinding the TiO2 powder and metal Mg evenly and then dispersing them in a solvent for ultrasonic treatment, followed by drying and grinding. Wherein, the grinding method may be conventional in the art, generally manual grinding. The grinding time may be 10-30 min, for example, 20 min. Wherein, the type of the solvent may be conventional in the art, such as anhydrous ethanol. The amount of the solvent may be conventional in the art, and the ratio of the sum of the masses of the TiO2 powder and metal Mg to the volume of the solvent may be (0.05-0.2) g / mL, for example, 0.1 g / mL. The ultrasonic treatment time may be conventional in the art, generally 10-180 min, for example, 20 min, 30 min, 40 min, 50 min, 60 min or 120 min.

[0046] The present invention also provides a porous titanium suboxide ceramic body prepared by the above-mentioned preparation method.

[0047] In the present invention, the shape of the porous titania ceramic body can be conventional in the art, such as a sheet.

[0048] In the present invention, when the porous titanium oxide ceramic body is porous TiO 0.5 When the ceramic body is TiO 0.5 The surface of the particles is preferably coated with a layer of TiO x Passivation layer. The TiO x The thickness of the passivation layer may be 5-10 nm.

[0049] In the present invention, the electrical conductivity of the porous titanium oxide ceramic body is preferably greater than 1.0×10 5 Sm -1 .

[0050] In the present invention, the pore size of the porous titania ceramic body is preferably 0.2 to 5 μm.

[0051] The present invention also provides a use of the aforementioned porous titanium suboxide ceramic body as a self-supporting catalyst carrier in the field of electrocatalysis.

[0052] In the present invention, the porous titania ceramic body is preferably in the shape of a sheet.

[0053] In the present invention, the electrocatalytic field can be electrocatalytic nitrate reduction to ammonia, electrocatalytic HER, electrocatalytic OER or electrocatalytic carbon dioxide reduction.

[0054] The present invention also provides an electrocatalytic device comprising an electrode, an ion exchange membrane and an electrolyte, wherein the electrode comprises a catalyst comprising the porous titanium suboxide ceramic body as described above.

[0055] In the present invention, the catalyst preferably comprises the porous titania ceramic body as described above and an active metal supported on the porous titania ceramic body.

[0056] The active metal may be conventional in the art, preferably one or more of Cu, Fe, Co and Ni.

[0057] In the present invention, the type of the ion exchange membrane may be an anion exchange membrane commonly used in the art, such as Fumasep FAB-PK-130 exchange membrane.

[0058] In the present invention, the electrolyte can be conventional in the art, such as a 1.0 M KOH aqueous solution containing 0.5 M KNO 3 .

[0059] The raw materials and reagents used in the present invention are all commercially available.

[0060] On the basis of conforming to the common sense in this field, the above-mentioned preferred conditions can be arbitrarily combined to obtain the preferred embodiments of the present invention.

[0061] The reagents and raw materials used in the present invention are commercially available.

[0062] The positive progress effect of the present invention is:

[0063] The porous titanium suboxide ceramic material prepared by the invention has a porous structure and high electrical conductivity, and the preparation method is simple, the cost is low, and it is conducive to industrial production. BRIEF DESCRIPTION OF THE DRAWINGS

[0064] Figure 1 The porous TiO prepared in Example 1 0.5 TEM image of powder scraped off a ceramic wafer;

[0065] Figure 2 The porous TiO prepared in Example 1 0.5 HADDF-STEM of powder scraped off a ceramic wafer;

[0066] Figure 3 The porous TiO prepared in Example 1 0.5 XRD pattern of powder scraped off the ceramic sheet;

[0067] Figure 4 The porous TiO prepared in Example 1 0.5 SEM of ceramic wafer;

[0068] Figure 5 The porous TiO prepared in Example 1 0.5 Comparison of UV-visible absorption spectra of powder scraped from ceramic sheet, Ti powder of Comparative Example 1, and TiO2 powder of Comparative Example 2;

[0069] Figure 6 The porous TiO prepared in Example 1 0.5 The conductivity test graph of ceramic sheets changing with temperature. DETAILED DESCRIPTION

[0070] The present invention is further illustrated by way of examples below, but the present invention is not limited to the scope of the examples. Experimental methods in the following examples where specific conditions are not specified were performed according to conventional methods and conditions, or selected according to the product specifications.

[0071] Example 1

[0072] Step (1) TiO 0.5 Powder preparation: TiO (99.9%, 100-200 mesh, Rhawn) and Ti (99.5%, 325 mesh, Innochem) were mixed in a quartz mortar at a molar ratio of 0.45:0.55 and ground for 20 minutes to mix thoroughly. 1 g of the mixed powder was added to a tableting mold with a diameter of 8 mm. The mixture was pressed to 4000 kg using a hydraulic press and maintained at this pressure for 15 seconds to form a tablet. The tablet mixture was placed in a pre-evacuated quartz tube and sealed with an oxyhydrogen flame to a vacuum of 10 -3 Pa. The vacuum glass tube containing the sample was placed in a muffle furnace and heated to 800°C at a rate of 5°C / min. The temperature was maintained at this temperature for 72 hours and then naturally cooled to room temperature. The glass tube was opened, the flake sample was taken out, and ground into powder in a quartz mortar to obtain TiO 0.5 powder.

[0073] Step (2) TiO 0.5 Sintering of TiO mixed ceramic sheets: 0.5 The powder and nano-MgO (99.9%, 50nm, Macklin) were mixed in a quartz mortar at a molar ratio of 1:1.5 and ground for 20 minutes to mix evenly. 1g of the mixed powder was added to a beaker, and 10mL of anhydrous ethanol was added. The mixture was sonicated in an ultrasonic machine for 30 minutes, and then poured into a Petri dish and dried in a 60℃ oven for 2 hours to remove the anhydrous ethanol. The dried TiO 0.5The mixture of TiO and MgO was ground in a quartz mortar for 20 minutes. Then, a spark plasma sintering (SPS) experiment was carried out using a mini SPS spark plasma furnace (SPS-3T-5-MIN, Shanghai Chenhua Technology Co., Ltd.) to prepare a porous support. A mixed powder with a mass of 1.0 g was loaded into a graphite mold with an inner diameter of 15 mm. The powder sample was separated from the graphite mold and punch with a 0.1 mm graphite paper. Under a uniaxial pressure of 0.54t, the mixed ceramic was heated to 1300°C at a rate of 100°C / min in a vacuum (≤10Pa), and then continued to heat to 1500°C at a rate of 50°C / min. The sample was kept at this temperature and pressure for 15 minutes and naturally cooled to room temperature to prepare TiO 0.5 and MgO mixed ceramic sheets. To minimize heat radiation, the mold is wrapped with graphite wool. TiO is removed by grinding with a grinding wheel. 0.5 Graphite on the surface of ceramic samples, and the prepared TiO 0.5 The ceramic samples were cut into square slices of 0.5 cm × 0.5 cm × 0.1 cm.

[0074] Step (3) Porous TiO 0.5 Preparation of ceramic sheet: TiO obtained in step (2) 0.5 The mixed ceramic sheet of TiO and MgO was etched in 200 mL 0.5 M H2SO4 (analytical grade, Chinese medicine) for 48 hours, and the dilute sulfuric acid solution was replaced every 16 hours to remove the magnesium oxide in the mixed ceramic sheet to obtain porous TiO 0.5 Ceramic pieces.

[0075] Example 2

[0076] Compared with Example 1, except that the calcination temperature in step (1) was changed from 800° C. to 700° C., other operations and conditions remained unchanged.

[0077] Example 3

[0078] Compared with Example 1, except that the TiO 0.5 Except that the molar ratio of powder and nano-MgO was changed to 1:1.1, other operations and conditions remained unchanged.

[0079] Example 4

[0080] Compared with Example 1, except that the TiO 0.5 Except that the molar ratio of powder and nano-MgO was changed to 1:1.8, other operations and conditions remained unchanged.

[0081] Example 5

[0082] Compared with Example 1, except that the heating conditions in step (2) are changed to: heating the mixed ceramic to 1500°C at a rate of 100°C / min in a vacuum (≤10Pa), keeping the sample at this temperature and pressure for 15 minutes, and naturally cooling to room temperature, other operations and conditions remain unchanged.

[0083] Example 6

[0084] Compared with Example 1, except that the 50 nm nano-MgO (99.9%, Macklin) in step (2) is replaced by 100 nm nano-MgO (99.9%, Macklin), other operations and conditions remain unchanged.

[0085] Example 7

[0086] Compared with Example 1, except that the etching time in step (3) is changed to 25 h, other operations and conditions remain unchanged.

[0087] Example 8

[0088] Compared with Example 1, except that the nano-MgO in step (2) is replaced by 500 nm aluminum oxide, other operations and conditions remain unchanged.

[0089] Example 9

[0090] Compared with Example 1, except that the nano-MgO in step (2) is replaced by 500 nm La2O3, other operations and conditions remain unchanged.

[0091] Example 10

[0092] Compared with Example 1, except that the nano-MgO in step (2) is replaced by 100-500 nm calcium oxide, other operations and conditions remain unchanged.

[0093] Example 11

[0094] Step (1): same as in Example 1;

[0095] Step (2): TiO 0.5 The powder and nano-MgO (99.9%, 50nm, Macklin) were mixed in a quartz mortar at a molar ratio of 1:1.5 and ground for 20 minutes to mix evenly. 1g of the mixed powder was added to a beaker, and 10mL of anhydrous ethanol was added. The mixture was sonicated in an ultrasonic machine for 30 minutes, and then poured into a Petri dish and dried in a 60℃ oven for 2 hours to remove the anhydrous ethanol. The dried TiO 0.5The mixture of TiO and MgO was ground in a quartz mortar for 20 minutes. After grinding, 1g of the mixed powder was added to a tablet mold with a diameter of 8mm. The mixed powder was pressed to 4000kg using an oil press and maintained at pressure for 15 seconds to compact the mixed powder into a sheet. The sheet mixture was transferred to a tube furnace and sintered under nitrogen protection. The temperature was increased to 1500℃ at a heating rate of 50℃ / min and maintained for 1 hour. It was then cooled naturally to room temperature to prepare TiO 0.5 and MgO mixed ceramic sheet. 0.5 The ceramic samples were cut into square slices of 0.5 cm × 0.5 cm × 0.1 cm.

[0096] Step (3): Same as Example 1.

[0097] Comparative Example 1

[0098] Titanium foam (Shante) was cut into square sheets of 0.5 cm×0.5 cm×0.1 cm.

[0099] Comparative Example 2

[0100] Titanium foam (Shangte) was cut into 0.5 cm × 0.5 cm × 0.1 cm square slices and placed in an alumina crucible. This was then placed in a muffle furnace and heated to 800°C at a rate of 5°C / min in an air atmosphere. This temperature was maintained for 5 hours to allow for full oxidation, and the crucible was then cooled to room temperature to obtain TiO2 flakes.

[0101] Effect embodiment

[0102] (1) Catalytic performance test

[0103] (a) Preparation of porous Ti2O ceramic sheets loaded with nano-Cu (Ti2O-Cu): 2 mL of 0.01 M Cu(NO3)·2xH2O (99.99%, Macklin) solution was added to a mixed solution of 30 mL of 1 M KOH (>95%, Macklin) and 0.5 M KNO3 (99.0%, Macklin) as the electrodeposition solution. The electrodeposition experiment was carried out using a standard three-electrode system of a CHI 760E electrochemical workstation. In this system, for alkaline electrolytes, a Hg / HgCl2 electrode and a graphite rod were used as the reference electrode and counter electrode, respectively. According to the equation (E vs.RHE=E vs.Hg / HgCl2+0.0592×pH+0.244V), all potential values ​​with Hg / HgCl2 were converted to potential values ​​with the reversible hydrogen electrode (RHE). The porous Ti2O2 ceramic sheets prepared in Examples 1-11 and the titanium foam sheet of Comparative Example 1 and the TiO2 sheet of Comparative Example 2 were respectively used as working electrodes, and twenty cycles of in-situ electrodeposition were performed between -0.4 V and 0.4 V and RHE (100 mV / s) by cyclic voltammetry (CV) to load copper thereon, thereby obtaining Ti2O2-Cu ceramic sheets, titanium foam-Cu sheets, and TiO2-Cu sheets of Comparative Example 2.

[0104] (b) Electrochemical measurements: Electrochemical measurements were performed using a CHI 760E electrochemical workstation in a standard three-electrode system (H-type electrolytic cell, Jiangsu Boco New Materials Technology Co., Ltd.). TiO-Cu ceramic sheets, Comparative Example 1 (Ti), and Comparative Example 2 (TiO) were used as working electrodes (all with an area of ​​0.25 cm 2 ). A Hg / HgCl2 electrode and a graphite rod were used as the reference electrode and the counter electrode, respectively, and the alkaline electrolyte was a 1.0 M KOH aqueous solution containing 0.5 M KNO3. The anion exchange membrane (AEM) was Fumasep FAB-PK-130, provided by Jiangsu Boco Co., Ltd. Linear sweep voltammetry (LSV) polarization curves were recorded at a scan rate of 5 mV / s. Before the LSV test, ten cyclic voltammetry measurements (100 mV / s) were performed to clean the catalyst surface. Unless otherwise stated, all linear voltammetry curves were recorded after three pre-scans to achieve stability.

[0105] (c) Detection of NH4 + :The area is 0.25cm 2 TiO 0.5-Cu ceramic sheet, Ti sheet of comparative example 1 and TiO2 sheet of comparative example 2 were used as working electrodes, respectively, in 25mL of 1.0M KOH and 0.5M KNO3 mixed solution, at potentials of -0.1V, -0.2V, -0.3, -0.4V and -0.5V vs. RHE for 15 minutes. The electrolyte after the experiment was collected as NH4 + Detection solution. NH4 + The indophenol blue method is used for quantification. The steps for determining ammonium ions by the indophenol blue method are as follows:

[0106] 1. Prepare Solution 1: Add 100 mL of deionized water to a beaker, add 4 g of sodium hydroxide, 5.2 g of sodium citrate, and 5.2 g of salicylic acid, and stir to obtain Solution 1 (a 1 M sodium hydroxide mixed solution containing 5% salicylic acid and 5% sodium citrate).

[0107] 2. Prepare solution 2: Add 34.8 mL of deionized water and 1 mL of sodium hypochlorite solution (available chlorine content 11% to 14%) to a beaker and stir to obtain solution 2 (0.05 M sodium hypochlorite solution).

[0108] 3. Prepare Solution 3: Add 10 mL of deionized water and 100 mg of sodium nitroferricyanide into a beaker and stir to obtain Solution 3 (1 wt % sodium nitroferricyanide solution).

[0109] 4. Prepare standard solution: Take 7 10mL test tubes and draw 10mg / L nitrogen element ammonium chloride (NH4 + -N) solution 0μL, 20μL, 40μL, 100μL, 200μL, 400μL, 600μL. Add 2mL solution 1, 1mL solution 2 and 0.2mL solution 3, add deionized water to make up to 10mL. Shake well, let it stand for 30 minutes, and measure the absorbance at a wavelength of 654-656nm by ultraviolet spectroscopy. That is, use a series of standard ammonium chloride solutions (0.1, 0.2, 0.5, 1, 2, 3mg / LNH4 + -N, the concentration refers to the mass concentration of nitrogen in the ammonium chloride solution), with the concentration of the standard solution as the horizontal axis and the absorbance value as the vertical axis, draw a standard curve and calculate the regression equation.

[0110] 5. Sample treatment: Take 0.2mL of the electrolyte after the experiment, add 2mL of solution 1, 1mL of solution 2 and 0.2mL of solution 3, and add deionized water to make up to 10mL. Shake well, let it stand for 30 minutes, and measure the absorbance at a wavelength of 654-656nm using UV spectroscopy. Then fit the obtained value with the calibration curve and combine it with the regression equation to obtain the corresponding NH4 + concentration.

[0111] The NH3 Faradaic efficiency is calculated as follows:

[0112]

[0113] Where Q represents the total coulombs applied (C), Q NH3 is the charge required to generate NH3, n is the number of electron transfers (8 for 1 mole of NH3), V is the volume of the cathode solution in the cathode compartment (25 mL), and F is the Faraday constant (96,485 C / mol).

[0114] The NH3 yield is calculated according to the following formula:

[0115]

[0116] Among them, C NH3 is the concentration of NH3 produced, V is the volume of the cathode electrolyte solution (L), t is the reduction time (h), and A is the area of ​​the working electrode (cm 2 ).

[0117] The test results at -0.5V vs. RHE are shown in Table 1:

[0118] Table 1

[0119]

[0120]

[0121] TiO prepared in Examples 1-7 0.5 Porous ceramic sheets have high electrical conductivity and high current density. By loading a small amount of Cu, a catalyst with high catalytic activity can be obtained.

[0122] (2) Morphology characterization and XRD testing

[0123] The porous TiO prepared in Example 1 0.5 The powder was scraped off the ceramic sheet and characterized by TEM, HADDF-STEM and XRD. The test results are shown in Figure 1-Figure 5 and Table 2.

[0124] According to TEM( Figure 1 )、HADDF-STEM( Figure 2 ) and XRD( Figure 3 ) It can be seen that Example 1 successfully prepared TiO 0.5 Ceramics, which have a high surface oxygen content, are TiO x The passivation layer helps the self-supporting catalyst to have good chemical stability. Figure 3 From the crystal data in Table 2, it can be seen that the porous TiO prepared in Example 1 0.5 TiO in ceramic sheets0.5 It belongs to the trigonal crystal system and its space group is P-3m1.

[0125] According to SEM ( Figure 4 ) It can be seen that the porous TiO prepared in Example 1 0.5 The ceramic sheet has a porous structure with a pore size of 0.2 to 5 μm.

[0126] Table 2 Porous TiO prepared in Example 1 0.5 Crystal data

[0127]

[0128]

[0129] (3) UV-vis test

[0130] The porous TiO prepared in Example 1 0.5 The powder scraped from the ceramic sheet, the Ti powder of Comparative Example 1, and the TiO2 powder of Comparative Example 2 were subjected to UV-vis testing to obtain the UV-visible absorption spectrum ( Figure 5 ).

[0131] (4) Conductivity test

[0132] The porous TiO prepared in Example 1 0.5 Ceramic pieces crushed into TiO 0.5 powder, and 0.5 g TiO 0.5 The powder was added to a tableting die with a diameter of 8 mm, and the pressure was increased to 4000 kg using a hydraulic press. The pressure was maintained for 15 seconds to compact the powder into flakes. 0.5 Cut into long strips of 0.2 cm × 0.2 cm × 1 cm. The temperature-dependent conductivity was obtained using a standard four-probe technique with a resistivity model and collected on a physical property measurement system (PPMS, Quantum Design). The test results are shown in Figure 6 .

[0133] Through UV-vis test and conductivity test, it can be found that the porous TiO prepared in Example 1 0.5 The ceramic sheet has metallic properties close to Ti, rather than the semiconductor properties of traditional TiO2.

[0134] Although specific embodiments of the present invention have been described above, those skilled in the art will appreciate that these are merely illustrative and that the scope of the present invention is defined by the appended claims. Those skilled in the art may make various changes or modifications to these embodiments without departing from the principles and essence of the present invention, and such changes and modifications are intended to fall within the scope of the present invention.

Claims

1. A method for preparing a porous titania ceramic body, characterized in that: The following steps are involved: Method 1: (1) TiO x The mixture of powder and metal oxide type ionic crystal is sintered or formed first and then sintered to prepare a TiO x and ceramic bodies of metal oxide type ionic crystals; (2) The TiO x The ceramic body of the metal oxide type ionic crystal is acid washed to obtain porous TiO x Ceramic body; wherein the TiO x In the case of 0<x≤1, Method 2: (1) Sintering a mixture of TiO2 powder and metal Mg into a mold or forming the mixture first and then sintering the mixture to prepare a TiO2 powder. x and a ceramic body of magnesium oxide; (2) The TiO x The ceramic body of magnesium oxide was acid washed to obtain porous TiO x Ceramic body; wherein the TiO x In the equation, 1≤x<2.

2. The method for preparing a porous titania ceramic body according to claim 1, wherein: Method 1: One or more of the following conditions are met: (1) the TiO x , x is 0.05, 0.1, 0.2, 0.25, 0.3, 0.33, 0.35, 0.4, 0.45, 0.5, 0.6 or 1.0; (2) When x is 0.5, the TiO x The preparation method of the powder comprises the following steps: tableting and calcining a mixture of TiO and Ti to obtain TiO 0.5 powder; (3) the TiO x The molar ratio of the powder to the metal oxide type ionic crystal is 1:(1.0-3.5), for example, 1:1.1, 1:1.2, 1:1.3, 1:1.5, 1:1.6, 1:1.8, 1:2.0 or 1:2.5; (4) the TiO x The preparation method of the mixture of powder and metal oxide type ionic crystal comprises the following steps: x The powder and the metal oxide type ionic crystal are ground uniformly, dispersed in a solvent, and ultrasonically treated, and then dried and ground.

3. The method for preparing a porous titania ceramic body according to claim 1, wherein: In method 1, the metal oxide type ionic crystal is one or more of alkali metal oxide, alkaline earth metal oxide, rare earth metal oxide and boron group metal oxide; Wherein, the alkali metal oxide is preferably sodium oxide and / or potassium oxide; the alkaline earth metal oxide is preferably one or more of magnesium oxide, calcium oxide, barium oxide and strontium oxide; the rare earth metal oxide is preferably one or more of La2O3, Ce2O3, Pr2O3, Nd2O3, Sm2O3, Eu2O3, Gd2O3, Tb2O3, Dy2O3, Ho2O3, Yb2O3, Er2O3 and Lu2O3; the boron group metal oxide is preferably one or more of aluminum oxide, gallium oxide and indium oxide; And / or, the particle size of the metal oxide ionic crystal is 10-600 nm, such as 20 nm, 30 nm, 40 nm, 50 nm, 80 nm, 100 nm, 150 nm, 200 nm, 300 nm or 500 nm, preferably 10-200 nm.

4. The method for preparing a porous titania ceramic body according to claim 1, wherein: In method 1 and / or method 2, the sintering is performed by spark plasma sintering; When the spark plasma sintering method is used, the pressure during the sintering process is preferably 25-50 MPa, such as 30 MPa, 35 MPa or 40 MPa; The rate of heating to the sintering temperature is preferably 40-110°C / min, for example 50°C / min, 80°C / min or 100°C / min; The sintering temperature is preferably 1000-1600°C, for example 1200°C, 1300°C or 1500°C; The sintering time is preferably 10-30 minutes, for example 15 minutes.

5. The method for preparing a porous titania ceramic body according to claim 1, wherein: In method 1 and / or method 2, when the method of forming first and then sintering is adopted, the sintering temperature is 1000-1600° C., for example, 1200° C., 1300° C., 1500° C. or 1550° C.; The sintering time may be 10 min-5 h, for example, 15 min, 30 min, 1 h, 2 h or 4.5 h.

6. The method for preparing a porous titania ceramic body according to claim 1, wherein: Method 2: One or more of the following conditions are met: (1) The particle size of the metal Mg is 10-200 nm, for example, 20 nm, 30 nm, 50 nm, 80 nm or 100 nm; (2) The molar ratio of the TiO2 powder to the metallic Mg is 1:(1.0-3.5), for example, 1:1.1, 1:1.2, 1:1.3, 1:1.5, 1:1.6, 1:1.8, 1:2.0 or 1:2.5; (3) The preparation method of the mixture of TiO2 powder and metal Mg may include the following steps: grinding the TiO2 powder and metal Mg uniformly, dispersing them in a solvent, performing ultrasonic treatment, and then drying and grinding them.

7. The method for preparing a porous titania ceramic body according to claim 1, wherein: In method 1 and / or method 2, the pickling satisfies one or more of the following conditions: (1) The acid used for pickling is one or a combination of sulfuric acid, hydrochloric acid and phosphoric acid; (2) The concentration of the acid used in the pickling is 0.05-5M, for example 0.2M, 0.5M, 1.5M or 2.0; (3) The pickling time is 20-100 hours, for example, 24 hours, 25 hours, 30 hours, 48 ​​hours, 60 hours or 96 hours.

8. A porous titania ceramic body prepared by the method for preparing a porous titania ceramic body according to any one of claims 1 to 7.

9. Use of the porous titania ceramic body according to claim 8 as a self-supporting catalyst carrier in the field of electrocatalysis.

10. An electrocatalytic device, characterized in that: The invention comprises an electrode, an ion exchange membrane and an electrolyte, wherein the electrode comprises a catalyst containing the porous titanium suboxide ceramic body as claimed in claim 8.

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