Photocatalytic reduction in rearrangement

Abstract

A method for photocatalytic reduction of rearrangements, and a setup including a photocatalyst having rearrangements are provided. [Solution] The present invention relates to a method for photocatalytic reduction at rearrangements, and a setup including a photocatalyst having rearrangements.

Description

[Technical Field]

[0001] The present invention relates to a method for photocatalytic reduction at dislocations and a setup including a photocatalyst having dislocations. As used herein, the term “at dislocations” includes both photocatalytic reactions at the dislocation site itself and photocatalytic reactions in the vicinity of the dislocation. For example, in some embodiments, the dislocation serves as a “highway” for electron conduction to the photocatalytic surface. [Background technology]

[0002] Over the past few decades, energy consumption, particularly from fossil fuels, has increased dramatically due to the rapid development of modern industry and the explosive growth of the population. Statistical data reveals that over 65% of total energy consumption in 2017 may have been attributable to fossil fuel sources. Oil companies estimate that remaining fossil resources will be depleted within decades if no changes are made. Finding appropriate solutions related to the efficient conversion of energy from renewable resources will have significant social and economic implications.

[0003] Large-scale consumption of fossil fuels inevitably leads to CO2 emissions into the environment. Given that CO2 is currently the dominant greenhouse gas, such emissions have already caused a 1.2°C global warming. In accordance with the Paris Agreement's objective of limiting warming to below 1.5°C, fossil fuel consumption should be restricted to low levels. Otherwise, the undesirable effects induced by global warming will be widespread. Therefore, we need to rely more heavily on renewable resources than on fossil fuels.

[0004] To this end, there is an urgent need for sustainable and environmentally friendly solutions related to energy conversion. Energy conversion through the production of synthetic fuels can support such efforts. For example, catalytic energy conversion using water, O2, or CO2 as reactants, driven by sunlight, has been proposed as a photocatalytic reaction. These reactants and sunlight are abundant in nature, which means that these energy conversion reactions can be realized in a clean and sustainable manner, offering a promising solution to both the energy crisis and global warming.

[0005] In 1972, researchers discovered the phenomenon of water splitting using TiO2 as a catalyst under ultraviolet (UV) irradiation. This suggested the potential for catalytic energy conversion driven by light. Inspired by such discoveries, extensive efforts have been made regarding semiconductor catalysts, and their applications in these energy conversions under light irradiation have expanded. Light irradiation, specifically sunlight, can be used to drive energy conversion reactions in combination with catalysts that have an optimal band gap for light absorption.

[0006] Aside from the classical photocatalytic reaction of water splitting, energy conversion related to photocatalytic reduction has attracted the most attention. For example, greenhouse gas CO2 is a major focus of research, as it can be reduced to various carbon-containing fuel forms, such as CO, CH4, CH3OH, CH3CH2OH, and others. Photocatalytic CO2 reduction is thus called "artificial photosynthesis." This offers a prospect for a carbon-neutral energy cycle based on the photocatalytic conversion of CO2. This involves the relationship between renewable energy consumption, CO2 emissions, and CO2 recycling. However, to date, a photocatalyst efficient enough to reduce CO2 with high selectivity for the resulting products has not been found.

[0007] Due to the inherently stable nature of the C=O bond and the highest oxidation state of carbon in CO2, photocatalytic CO2 reduction generally faces challenges such as low energy conversion efficiency, diverse but uncontrollable reaction pathways and products, and competing H2 production from water in the reactant solution. Furthermore, recombination of photogenerated holes with electrons is inevitable, especially in the bulk of the catalyst. This prevents electrons from moving to the reaction surface sites to reduce CO2. All these factors limit the product yield from CO2 reduction to a small amount. For example, in the case of rutile TiO2 particles, the CH4 product is 0.225 μmol / g per hour, and the CO product is 0.188 μmol / g per hour. Here, the weight of the catalyst is used to normalize the molar amount of the product.

[0008] Various approaches have been developed to improve the efficiency of photocatalytic CO2 conversion, including impurity doping, metal deposition, heterojunction configurations, and cocatalytic loading. However, so far, none have been found to be effective. Even in cases where the photochemical reduction of CO2 has been successful, only gaseous components (e.g., CH4, CO) have been obtained. Nevertheless, readily separable liquid products offer significant industrial advantages.

[0009] Another photocatalytic reaction of industrial interest is the production of H2O2 from a two-electron reduction process of O2, driven by light irradiation. Besides being a powerful industrial oxidant, H2O2 is crucial in the fuel cell sector, due to its annual consumption of approximately 2.2 million tons. Using naturally abundant O2 as the reactant and driving the reaction by light irradiation to produce H2O2 makes the conversion more sustainable and environmentally friendly compared to the currently used anthraquinone oxidation (AO) process. However, to date, industrially viable strategies have not been developed for such cases. Regarding H2O2 production, there is a method that has been used for almost a century and remains dominant in the industry. This method involves expensive Pd-containing catalysts, low H2O2 selectivity, and the risk of explosion from the resulting H2 / O2 mixture. Therefore, a sustainable solution is needed for such an important chemical. [Overview of the Initiative]

[0010] A photocatalyst with an appropriate band gap can absorb light with a corresponding wavelength range. When the absorbed photon energy is large enough to overcome the band gap, electrons and holes are activated and generated. Thus, by applying a small bias voltage under light irradiation, the generated photocurrent can be measured in a closed circuit. When light irradiation is off, there is no photogenerated charge; therefore, no photocurrent is induced. A schematic diagram of the mechanism is shown in Figure 1. These photogenerated holes and electrons are utilized in the photocatalytic reactions described below and form the basis of these reactions.

[0011] Typically, the wavelength range for photocatalytic measurements is 320 nm to 780 nm. This wavelength range includes ultraviolet A (UVA) (320 to 400 nm) and visible light (400 to 780 nm), but does not include ultraviolet B (UVB) (280 to 320 nm), ultraviolet C (UVC) (100 to 280 nm), or infrared (>780 nm). UVB and UVC are widely absorbed by the atmosphere and hardly reach the Earth's surface. Therefore, sunlight reaching the Earth contains very little UVB and UVC. In general, infrared radiation is not used in photocatalytic reactions.

[0012] Using various experimental methods to introduce a dislocation network into several ceramic photocatalysts, the inventors demonstrated an increase in catalytic efficiency for multiple chemical reduction reactions utilizing the generated electron charge carriers.

[0013] Dislocations can be introduced into catalytic materials by various methods. These methods include bulk uniaxial deformation and surface treatments such as localized ball indentation, polishing, grinding, or rolling performed at both room temperature and high temperatures. The methods can also be periodically accelerated to further increase the dislocation density. In addition, although it has been claimed that suitable sintering conditions (e.g., flash sintering, spark plasma sintering) are feasible for the synthesis of polycrystalline ceramics, this has not been confirmed for some materials.

[0014] The industrially desired photochemical reduction of CO2 from aqueous solutions was efficiently achieved by introducing rearrangements into the catalyst, both in combination with and without sacrificial agents.

[0015] The products of photochemical CO2 reduction exhibited high selectivity compared to liquid organic products. This offers significant economic advantages and industrial feasibility compared to gaseous reduction.

[0016] Photochemical synthesis of H2O2 has been successfully enhanced to pave the way for efficient industrial-scale production with and without sacrificial agents. Sacrificial agents include dyes, alcohols, oxalates, nitrates, nitrites, sulfites, and metal cations. These can be used to capture electrons or holes for redox reactions. H2O2 production reactions include both oxygen reduction (ORR) and hydroxylation (WOR) reactions. Photocatalysts used for H2O2 production via the ORR pathway preferably have a conduction band (CB) negative than 0.68 V, and photocatalysts used for H2O2 production via the WOR pathway preferably have a valence band (VB) positive than 1.76 V. [Brief explanation of the drawing]

[0017] [Figure 1] Figure 1 shows, on the left, the photogenerated holes (h+) and electrons (e-) in the photocatalyst 11 when irradiated with light 12. The band gap between the valence band 13 and the conduction band 14 is shown as Eg. The right side of Figure 1 schematically shows a photocatalyst with ordered dislocations at the top and a photocatalyst with disordered dislocations at the bottom. The solid T-shaped structures represent inserted lattice half-planes, which terminate at edge dislocations. The dashed lines show traces of each dislocation. Generally, dislocations can be edge dislocations, helical dislocations, or mixed types of the above. Here, for simplicity, we will simply refer to them collectively as dislocations. [Figure 2] Figure 2 schematically shows catalysts with a high dislocation density of ordered dislocations (Figure 2(a)), a high dislocation density of irregular dislocations (Figure 2(b)), and a low dislocation density (Figure 2(c)). The solid T-shaped structures represent inserted lattice half-planes, which terminate at edge dislocations. The dashed lines show traces of each dislocation. [Figure 3] Figure 3 shows a typical uniaxial stress-strain curve illustrating the deformation of BaTiO3 at 1150°C to introduce a defined ordered dislocation structure in the sliding system. The 0.2% yield stress (σ0.2) is marked at 43.5 MPa. [Figure 4]Figure 4 is an optical microscope image showing regions resulting from repeating surface ball indentations of SrTiO3, which lead to irregular dislocations. [Figure 5] Figure 5 is a schematic diagram of an electrochemical setup 51 including a photocatalytic working electrode 52 immersed in an aqueous solution 53. A typical three-electrode configuration is shown with one platinum plate formed as the counter electrode 54 and one Ag / AgCl electrode as the reference electrode 55. The electrochemical setup further includes an electrochemical workstation 56 for photocurrent measurement. The aqueous solution 53 containing the photocatalytic working electrode 52 is irradiated with light 57. [Figure 6] Figure 6 shows the photocurrent responses for five irradiation on-off cycles measured in a uniaxially deformed BaTiO3 sample with high / low dislocation density. [Figure 7] Figure 7 shows the photocurrent response for six irradiation on-off cycles measured in a uniaxially deformed TiO2 sample with high / low dislocation density. [Figure 8] Figure 8 shows the photocurrent responses for six irradiation on-off cycles measured in surface-treated SrTiO3 samples with high / low dislocation densities. [Figure 9] Figure 9 shows the results of photocatalytic conversion from CO2 reduction using BaTiO3 as a photocatalyst, with a bicarbonate solution (NaHCO3) in which CO2 gas was bubbled internally, and triethanolamine used as a sacrificial agent. (a) and (b) show the results obtained from photocatalysts with high dislocation density, and (c) and (d) show the results obtained from photocatalysts with low dislocation density. [Figure 10] Figure 10 shows the results of photocatalytic conversion resulting from CO2 reduction using TiO2 as a photocatalyst, with a bicarbonate solution (NaHCO3) in which CO2 gas was bubbled internally, and triethanolamine used as a sacrificial agent. [Figure 11]Figure 11 shows the results of photocatalytic conversion resulting from CO2 reduction using SrTiO3 as a photocatalyst, with a bicarbonate solution (NaHCO3) that was not bubbled with CO2 gas internally, and triethanolamine used as a sacrificial agent. [Figure 12] Figure 12 shows the results of photocatalytic conversion resulting from CO2 reduction using TiO2 as a photocatalyst, without the use of a sacrificial agent, and using deionized water obtained by bubbling CO2 gas. [Figure 13] Figure 13 shows the results of photocatalytic H2O2 production using deionized water and bubbling air as reactants, and BaTiO3 as a catalyst under light irradiation. [Figure 14] Figure 14 shows the results of photocatalytic H2O2 production using deionized water and bubbling pure O2 as reactants, and BaTiO3 as a catalyst under light irradiation. [Figure 15] Figure 15 shows the results of a photocatalytic H2O2 generation cycle using deionized water and bubbling pure O2 as reactants, and BaTiO3 as a catalyst under light irradiation. [Figure 16] Figure 16 shows the results of photocatalytic H2O2 production using deionized water and bubbling pure O2 as reactants, and TiO2 as a catalyst under light irradiation. [Figure 17] Figure 17 shows the results of a photocatalytic H2O2 generation cycle using deionized water and bubbling pure O2 as reactants, and TiO2 as a catalyst under light irradiation. [Figure 18]Figure 18 is a scanning transmission electron microscope (STEM) image visualizing dislocations in a (001) slice of BaTiO3 (BTO) from high-temperature deformation. Since the image in Figure 18 is a two-dimensional projection, the imaged dislocations represent projections of dislocation lines of surface dislocations. Typical projected dislocation morphologies, such as dots or short segments, are indicated by arrowheads. The magnification was 20,000x. The scale bar indicates 2 μm. The total image area is 36 × 10⁻¹² m². The number of imaged dislocations is 70. Therefore, the surface dislocation density is obtained by dividing 70 by 36 × 10⁻¹² m², which is approximately 2 × 10¹² m². [Modes for carrying out the invention]

[0018] Details of the invention The present invention relates to a method for photocatalytic reduction at rearrangements, and to an electrochemical setup including a photocatalyst having rearrangements.

[0019] Specifically, the present invention is a method for photocatalytic reduction of a reactant, wherein the method comprises the following steps, i.e. a) Prepare a setup including a photocatalyst immersed in an aqueous solution containing the reactant, and b) Specifically, the photocatalyst is irradiated with light such that the photocatalyst-reactant interface near or at the rearrangement acts as a reaction site for the photocatalytic reaction, c) Optionally, separate the liquid (specifically organic) product. This relates to a method for the photocatalytic reduction of reactants, including the process steps.

[0020] The method is characterized in that the photocatalyst includes a semiconductor photocatalyst containing dislocations, or consists of a semiconductor photocatalyst containing dislocations, and the surface dislocation density on at least a portion of the surface of the photocatalyst is at least 1.0 × 10⁻⁶ 11 m -2The present invention is characterized by the following: Optionally, the portion of the surface having the desired dislocation density is at least 20%, at least 40%, at least 60%, or at least 80% of the total surface area of ​​the photocatalyst. In this context, surface dislocation density means the number of dislocations within the area of ​​the photocatalyst surface, i.e., the number of dislocations whose dislocation lines terminate at the surface of the photocatalyst. The photocatalyst of the present invention preferably absorbs light from the visible light range to UV. Specifically, the photocatalyst of the present invention absorbs light in the wavelength range of 320 nm to 780 nm, including ultraviolet A (UVA) (320 to 400 nm) and visible light (400 to 780 nm).

[0021] A dislocation is a linear defect. If this line penetrates a surface, then it is valid on that surface.

[0022] As used herein, the terms “liquid” and “gaseous” refer to the state of the respective products at standard temperature and pressure (NTP, 20°C, 101.325 kPa), unless otherwise specified. The products of the methods of the present invention may include liquid products, gaseous products, and / or mixtures of liquid and gaseous products. Gaseous products may include, for example, H2, CO, or mixtures thereof. Liquid products may be polar organic products. Liquid products are preferably water-soluble. Specifically, water may be the solvent. Liquid products are specifically liquid organic products. Liquid products may include, for example, ketones, aldehydes, alcohols, and / or mixtures of two or more of these, such as CH2O, CH3OH, CH3CHO, CH3CH2OH, and / or mixtures of two or more of these. The method may optionally include a step of separating the liquid products, for example, by distillation under different pressures, if an azeotropic mixture is formed with water.

[0023] In some embodiments, the band gap of the photocatalyst is 1.0 eV to 5.5 eV, 1.5 eV to 5.0 eV, 2.0 eV to 4.5 eV, or 2.5 eV to 4.0 eV, for example, 3.0 to 3.5 eV. The band gap may optionally be at least 1.0 eV, at least 1.5 eV, at least 2.0 eV, at least 2.5 eV, or at least 3.0 eV. The band gap may optionally be up to 5.5 eV, up to 5.0 eV, up to 4.5 eV, up to 4.0 eV, or up to 3.5 eV. In some embodiments, the band gap may be about 3.1 eV (specifically for TiO2) or about 3.2 eV (specifically for SrTiO3).

[0024] In some embodiments, the setup is an electrochemical setup, and the photocatalyst is a photocatalytic working electrode.

[0025] In some embodiments, the method includes a step of detecting and quantifying the products from the photocatalytic reaction.

[0026] The light preferably includes electromagnetic rays with wavelengths of 320 nm to 780 nm. For example, the light source for irradiating the photocatalytic working electrode may be a Xe arc lamp. Xe arc lamps are particularly preferred because they produce bright white light to mimic sunlight.

[0027] Specifically, the aqueous solution contains more than 50 vol% H2O, for example, at least 60 vol%, at least 70 vol%, at least 80 vol%, at least 90 vol%, at least 95 vol%, at least 98 vol%, or at least 99 vol% H2O.

[0028] In some embodiments, the aqueous solution is deionized water. In other embodiments, it specifically contains one or more inorganic salts in a total amount of at least 10 mM, at least 20 mM, at least 50 mM, at least 100 mM, at least 200 mM, or at least 500 mM. The total amount of inorganic salts is preferably up to 8.0 M, for example, up to 7.0 M, up to 6.0 M, up to 5.0 M, up to 4.0 M, or up to 3.0 M. The total amount of inorganic salts may be, for example, 10 mM to 8.0 M, 20 mM to 7.0 M, 50 mM to 6.0 M, 100 mM to 5.0 M, 200 mM to 4.0 M, or 500 mM to 3.0 M.

[0029] The pH of the aqueous solution is specifically between 5.5 and 8.5, for example, between 6.0 and 8.0, or between 6.5 and 7.5. The pH of the aqueous solution may be, for example, at least 5.5, at least 6.0, or at least 6.5. The pH of the aqueous solution may be, for example, up to 8.5, up to 8.0, or up to 7.5.

[0030] The aqueous solution may optionally contain one or more sacrificial agents. The sacrificial agents can be used to capture electrons or holes for the redox reaction. In some embodiments, the aqueous solution contains a sacrificial agent. In other embodiments, the aqueous solution does not contain a sacrificial agent. In some embodiments, the sacrificial agent is selected from the group consisting of dyes, alcohols, oxalates, nitrates, nitrites, sulfites, metal cations, and combinations of two or more of these. In some embodiments, the sacrificial agent is selected from the group consisting of aliphatic amines, aromatic amines, ascorbic acid, and combinations of two or more of these. Triethanolamine is a particularly preferred sacrificial agent.

[0031] The volume ratio of the sacrificial agent to the total volume of the aqueous solution may be, for example, 1:20 to 1:5, 1:15 to 1:7, or 1:12 to 1:8, specifically about 1:10. In some embodiments, the volume ratio of the sacrificial agent to the total volume of the aqueous solution is at least 1:20, at least 1:15, or at least 1:12. In some embodiments, the volume ratio of the sacrificial agent to the total volume of the aqueous solution is at most 1:5, at most 1:7, or at most 1:8.

[0032] The reactant is specifically CO2 / HCO3 - / CO3 2- or may contain or consist of O2. The reactant may contain H2O or consist of H2O. Specifically, H2O may participate in the reaction and act as an intermediate medium for photogenerated electron transfer.

[0033] In some embodiments, the reactant is CO2 / HCO3 - / CO3 2- and contains or consists of this. In an aqueous solution, CO2 is in equilibrium with HCO3 - and CO3 2- Therefore, the present disclosure refers to "CO2 / HCO3 - / CO3 2- " as a reactant. An aqueous solution containing CO2 / HCO3 - / CO3 2- can be provided in various ways. Specifically, the aqueous solution may be a carbonate solution or a bicarbonate solution (specifically NaHCO3) with or without bubbling CO2 gas inside, or the aqueous solution may be deionized water with or without bubbling CO2 gas inside.

[0034] For example, in some embodiments, a bicarbonate solution (specifically NaHCO3) may be bubbled with CO2 gas, specifically until CO2 saturation is reached. The gas pressure of the bubbling CO2 gas is preferably equal to atmospheric pressure (101 kPa) or higher than atmospheric pressure in order to completely expel the dissolved oxygen.

[0035] In some embodiments, the bicarbonate solution (specifically NaHCO3) may be used without bubbling CO2 gas inside.

[0036] In some embodiments, deionized water may be bubbled with CO2 gas, specifically until CO2 saturation is reached. As described above, the gas pressure of the bubbling CO2 gas is preferably equal to or higher than atmospheric pressure (101 kPa) in order to completely remove the dissolved oxygen.

[0037] The bubbling CO2 gas is not necessarily pure CO2 and may contain other components. However, the proportion of CO2 in the bubbling CO2 gas is preferably greater than the proportion of CO2 in the air. More preferably, CO2 is the main component of the bubbling CO2 gas. The proportion of CO2 in the bubbling CO2 gas is preferably at least 50 vol%, more preferably at least 75 vol%, more preferably at least 90 vol%, more preferably at least 95 vol%, more preferably at least 98 vol%, more preferably at least 99 vol%, more preferably at least 99.9 vol%, more preferably at least 99.99 vol%, and more preferably at least 99.999 vol%.

[0038] CO2 / HCO3 - / CO3 2-The products obtained by reduction specifically include CO, CH4, CH2O, CH3OH, CH3CHO, CH3CH2OH, or mixtures of two or more of these. Ketones, aldehydes, alcohols, and / or mixtures of two or more of these, such as CH2O, CH3OH, CH3CHO, CH3CH2OH, or combinations thereof, are particularly preferred. A specific advantage of the present invention is to provide a photochemical CO2 reduction method with high selectivity toward liquid organic products, which has significant economic advantages and industrial feasibility compared to gaseous products. The distinction between liquid and gaseous products refers to the state of matter at standard temperature and pressure. Specifically, the molar ratio of liquid to gaseous products obtained by the method of the present invention is at least 1:1. For example, the molar ratio of the liquid product to the total product may be at least 50 mol%, for example, at least 60 mol%, at least 70 mol%, at least 80 mol%, at least 90 mol%, at least 95 mol%, at least 98 mol%, or at least 99 mol%.

[0039] In some embodiments, the reactant consists of O2. In such embodiments, the aqueous solution may specifically be deionized water bubbling to saturation, preferably with air or O2. The bubbling O2 gas is not necessarily pure O2 and may contain other components. However, the proportion of O2 in the bubbling O2 gas is preferably greater than the proportion of O2 in the air. More preferably, O2 is the main component of the bubbling O2 gas. The proportion of O2 in the bubbling O2 gas is preferably at least 50 vol%, more preferably at least 75 vol%, more preferably at least 90 vol%, more preferably at least 95 vol%, more preferably at least 98 vol%, more preferably at least 99 vol%, more preferably at least 99.9 vol%, more preferably at least 99.99 vol%, and more preferably at least 99.999 vol%.

[0040] The products obtained by the reduction of O2 specifically include H2O2. Preferably, H2O2 is the main product of the O2 reduction. For example, the molar ratio of H2O2 to the total product may be at least 50 mol%, for example, at least 60 mol%, at least 70 mol%, at least 80 mol%, at least 90 mol%, at least 95 mol%, at least 98 mol%, or at least 99 mol%.

[0041] According to the present invention, the method is carried out using a setup that includes a photocatalyst immersed in an aqueous solution containing the reactant.

[0042] In some embodiments, the setup is an electrochemical setup, and the photocatalyst is a photocatalytic working electrode. The electrochemical setup may further include a counter electrode (specifically a platinum electrode) and / or a reference electrode (specifically an Ag / AgCl electrode). The electrochemical setup may further include an electrochemical workstation.

[0043] This invention relates to a pure photocatalytic reaction. In some embodiments, an electrochemical setup (application of an additional voltage) is optionally used. Specifically, a workstation may be used to demonstrate the presence of an induced photocurrent.

[0044] The core of this invention is a photocatalyst. According to this invention, the photocatalyst includes a semiconductor photocatalyst containing dislocations, or comprises a semiconductor photocatalyst containing dislocations, and has a surface dislocation density of at least 1.0 × 10 11 m -2 That is the case.

[0045] The photocatalyst of the present invention is a semiconductor, specifically a polycrystalline ceramic or a single-crystal ceramic as a bulk ceramic or film. In some embodiments, the photocatalyst includes or consists of a transition metal oxide. Preferably, the photocatalyst includes or consists of BaTiO3, SrTiO3, or TiO2.

[0046] In some embodiments, the photocatalyst has a conduction band negative to 0.68 V and / or a valence band positive to 1.76 V.

[0047] The photocatalyst contains dislocations. The surface dislocation density is at least 1.0 × 10⁻⁶. 11 m -2 For example, at least 2.0 × 10 11 m -2 , at least 5.0 × 10 11 m -2 , at least 1.0 × 10 12 m -2 , at least 2.0 × 10 12 m -2 , at least 5.0 × 10 12 m -2 , or at least 1.0 × 10 13 m -2 In some embodiments, the surface dislocation density can reach up to 1.0 × 10⁻⁶. 17 m -2 , up to 5.0×10 16 m -2 , up to 2.0×10 16 m -2 , maximum 1.0×10 16 m -2 , up to 5.0×10 15 m -2 , up to 2.0×10 15 m -2 , or up to 1.0 × 10 15 m -2 The surface dislocation density is, for example, 1.0 × 10⁻⁶. 11 m -2 ~1.0×10 17 m -2 , 2.0×10 11 m -2 ~5.0×10 16 m -2 , 5.0×10 11 m -2 ~2.0×10 16 m -2 , 1.0 × 10 12 m -2 ~1.0×10 16 m -2 , 2.0×10 12 m -2 ~5.0×1015 m -2 , 5.0×10 12 m -2 ~2.0×10 15 m -2 , or 1.0 × 10 13 m -2 ~1.0×10 15 m -2 That's fine.

[0048] Quantification of surface dislocation density can be specifically performed by transmission electron microscopy (TEM) or scanning transmission electron microscopy (STEM). These methods are well known to those skilled in the art. Specifically, a thin sample with a thickness of less than about 100 nm, for example, about 20 nm, is prepared by preferably grinding and ion milling to obtain electron transparency. The diffraction contrast then enables imaging and quantification of dislocations, and allows for determination of the surface density of dislocations. A typical STEM image is shown in Figure 18.

[0049] This technique relies on imaging a small surface area, but it clearly indicates whether or not an enhanced dislocation density is imprinted (specifically, an imprinted dislocation structure results in a density at least 100 times greater than that of an untreated sample). Furthermore, the small area specifically represents the surface dislocation density of a portion of the photocatalyst's total surface area that is at least 20%, at least 40%, at least 60%, or at least 80%, and this can enable the determination of this surface dislocation density.

[0050] The method of the present invention is characterized in particular by its high product yield and conversion efficiency. CO2 conversion efficiency can be evaluated by the carbon content ratio of the product / reactant.

[0051]

number

[0052] CO2 / HCO3 - The molar amount of carbon n (carbon) contained in the reactant 反応物質This can be calculated using the law of ideal gases. The molar amount of carbon contained in the product is n(carbon). 生成物 This can be quantified from chromatographic analysis. Therefore, the CO2 conversion efficiency can be calculated using the above formula.

[0053] The CO2 conversion efficiency of the method of the present invention may be, for example, at least 40%, at least 50%, at least 60%, or at least 70%. In some embodiments, the CO2 conversion efficiency may be up to 90%, up to 85%, up to 80%, or up to 75%. The CO2 conversion efficiency may be, for example, 40% to 90%, 50% to 85%, 60% to 80%, or 70% to 75%.

[0054] The method of the present invention is specifically carried out at a temperature greater than 0°C and less than 100°C, for example, 1°C to 90°C, 2°C to 80°C, 3°C to 70°C, 4°C to 60°C, 5°C to 55°C, 6°C to 50°C, 7°C to 45°C, 8°C to 40°C, 9°C to 35°C, or 10°C to 30°C, for example, 11°C to 25°C, 12°C to 20°C, or 13°C to 17°C. The temperature may be, for example, at least greater than 0°C, for example, at least 1°C, at least 2°C, at least 3°C, at least 4°C, at least 5°C, at least 6°C, at least 7°C, at least 8°C, at least 9°C, at least 10°C, at least 11°C, at least 12°C, or at least 13°C. The temperature may be, for example, less than 100°C, for example, 90°C, 80°C, 70°C, 60°C, 55°C, 50°C, 45°C, 40°C, 35°C, 30°C, 25°C, 20°C, or 17°C. The method of the present invention is specifically carried out at standard atmospheric pressure (1 atm).

[0055] The present invention also includes a semiconductor photocatalyst containing dislocations, or a setup including a photocatalyst comprising a semiconductor photocatalyst containing dislocations, wherein the surface dislocation density is at least 1.0 × 10 11 m -2 This concerns the setup.

[0056] In some embodiments, the setup is an electrochemical setup, and the photocatalyst is a photocatalytic working electrode. The electrochemical setup may further include a counter electrode (specifically a platinum electrode) and / or a reference electrode (specifically an Ag / AgCl electrode). The electrochemical setup may further include an electrochemical workstation.

[0057] According to the present invention, the photocatalyst comprises a semiconductor photocatalyst containing dislocations, or consists of a semiconductor photocatalyst containing dislocations, and has a surface dislocation density of at least 1.0 × 10 11 m -2 That is the case.

[0058] The photocatalyst of the present invention is a semiconductor, specifically a polycrystalline ceramic or a single-crystal ceramic. In some embodiments, the photocatalyst includes or consists of a transition metal oxide. Preferably, the photocatalyst includes or consists of BaTiO3, SrTiO3, or TiO2. In some embodiments, the photocatalyst includes or consists of (Ba,Sr)TiO3.

[0059] In some embodiments, the photocatalyst includes or consists of a titanate ceramic, specifically a ceramic having the molecular formula RTiO3, where R is an alkaline earth metal, or a combination of two or more alkaline earth metals.

[0060] In some embodiments, the photocatalyst has a conduction band negative than 0.68 V and / or a valence band positive than 1.76 V. The band gap may be specifically 1.0 eV to 5.5 eV, 1.5 eV to 5.0 eV, 2.0 eV to 4.5 eV, or 2.5 eV to 4.0 eV, for example, 3.0 to 3.5 eV. The band gap may optionally be at least 1.0 eV, at least 1.5 eV, at least 2.0 eV, at least 2.5 eV, or at least 3.0 eV. The band gap may optionally be up to 5.5 eV, up to 5.0 eV, up to 4.5 eV, up to 4.0 eV, or up to 3.5 eV. In some embodiments, the band gap of the photocatalyst is 1.59 eV to 3.88 eV.

[0061] The photocatalyst contains dislocations. The surface dislocation density is at least 1.0×10 11 m -2 , for example, at least 2.0×10 11 m -2 , at least 5.0×10 11 m -2 , at least 1.0×10 12 m -2 , at least 2.0×10 12 m -2 , at least 5.0×10 12 m -2 , or at least 1.0×10 13 m -2 . In some embodiments, the surface dislocation density is at most 1.0×10 17 m -2 , at most 5.0×10 16 m -2 , at most 2.0×10 16 m -2 , at most 1.0×10 16 m -2 , at most 5.0×10 15 m -2 , at most 2.0×10 15 m -2 , or at most 1.0×10 15 m -2 . The surface dislocation density is, for example, 1.0×10 11 m -2 ~1.0×10 17 m -2 , 2.0×10 11 m -2 ~5.0×10 16 m -2 , 5.0×10 11 m -2 ~2.0×10 16 m -2 , 1.0×10 12 m -2 ~1.0×10 16 m -2 , 2.0×10 12 m -2 ~5.0×10 15 m -2 , 5.0×10 12 m -2~2.0×10 15 m -2 , or 1.0 × 10 13 m -2 ~1.0×10 15 m -2 That's fine.

[0062] The setup preferably includes a light source configured to irradiate the photocatalyst. The light source for irradiating the photocatalyst is, for example, a Xe arc lamp. A Xe arc lamp is particularly preferred because it produces bright white light to mimic sunlight.

[0063] The present invention also relates to a photocatalytic reduction method for reactants, specifically to the use of the setup of the present invention in the method of the present invention.

[0064] The present invention also relates to a method for the photocatalytic reduction of a reactant, more specifically, to a method of the present invention in which the surface dislocation density is at least 1.0 × 10⁻⁶ 11 m -2 This relates to the use of semiconductor photocatalysts containing dislocations as photocatalysts or in photocatalysts.

[0065] The present invention also relates to a surface dislocation density of at least 1.0 × 10⁻⁶ 11 m -2 A method for preparing a semiconductor photocatalyst containing a dislocation, wherein the method comprises the following steps, i.e. Specifically, the uniaxial or biaxial macro-deformation of semiconductor photocatalysts at temperatures ranging from room temperature to 1600°C, for example, 100°C to 1500°C, 200°C to 1400°C, 300°C to 1300°C, 400°C to 1200°C, 500°C to 1100°C, 600°C to 1000°C, 700°C to 900°C, or 750°C to 850°C. Surface treatment of a semiconductor photocatalyst, wherein the surface treatment includes indentation, polishing, grinding, rolling, scratching, or a combination of two or more of these. The present invention relates to a method for preparing a semiconductor photocatalyst, comprising one or more of the following steps. The above can be carried out in one or more cycles.

[0066] In some embodiments, the uniaxial or biaxial macro-deformation of the semiconductor photocatalyst is performed at temperatures ranging from room temperature (specifically, about 20°C) to 1000°C.

[0067] The term "room temperature" as used in this disclosure specifically means a temperature of 20°C.

[0068] The uniaxial or biaxial macro-deformation of the semiconductor photocatalyst may be carried out at temperatures such as, for example, at room temperature (specifically, at least about 20°C), at least 100°C, at least 200°C, at least 300°C, at least 400°C, at least 500°C, at least 600°C, at least 700°C, or at least 750°C. The uniaxial or biaxial macro-deformation of the semiconductor photocatalyst may be carried out at temperatures such as, for example, up to 1600°C, up to 1500°C, up to 1400°C, up to 1300°C, up to 1200°C, up to 1100°C, up to 1000°C, up to 900°C, or up to 850°C.

[0069] In some embodiments, uniaxial or biaxial deformation includes at least 0.5% and / or up to 30% plastic deformation. Uniaxial or biaxial deformation may include, for example, 0.5% to 30%, 1.0% to 15%, or 2.0% to 10% plastic deformation. Uniaxial or biaxial deformation may include, for example, at least 0.5%, at least 1.0%, or at least 2.0% plastic deformation. Uniaxial or biaxial deformation may include, for example, up to 30%, up to 15%, or up to 10% plastic deformation.

[0070] In some embodiments, uniaxial or biaxial deformation is a uniaxial or biaxial macro-deformation.

[0071] In some embodiments, uniaxial or biaxial deformation is performed under load control or displacement control.

[0072] In some embodiments, the surface treatment includes indentation.

[0073] The load on the indenter is specifically between 1.0N and 100N, for example, between 2.0N and 50N, or between 5.0N and 25N. The load on the indenter may optionally be at least 1.0N, at least 2.0N, or at least 5.0N. The load on the indenter may optionally be a maximum of 100N, a maximum of 50N, or a maximum of 25N.

[0074] In some embodiments, the contact length between the indenter and the semiconductor photocatalyst is 100 μm to 1.0 mm, for example, 200 μm to 500 μm. The contact length between the indenter and the semiconductor photocatalyst may optionally be at least 100 μm or at least 200 μm. The contact length between the indenter and the semiconductor photocatalyst may optionally be up to 1.0 mm or up to 500 μm.

[0075] The indenter material is specifically harder than the material to be indented. In some embodiments, the indenter material includes hardened steel, or hard metal, or materials used for ball bearings, such as SiC and Si3N4 or ZrO2. In some embodiments, the indenter material includes a material selected from the group consisting of steel (specifically hardened steel), SiC, Si3N4, ZrO2, and combinations of two or more of these.

[0076] In some embodiments, the surface treatment includes polishing, grinding, rolling, scratching, or a combination of two or more of these. In some embodiments, the lateral speed of the polishing, grinding, rolling, or scratching tool on the surface of the semiconductor catalyst is 0.01 mm / s to 10 mm / s, for example, 0.02 mm / s to 5.0 mm / s, 0.05 mm / s to 2.0 mm / s, 0.1 mm / s to 1.0 mm / s, or 0.2 mm / s to 0.5 mm / s. The lateral speed of the polishing, grinding, rolling, or scratching tool on the surface of the semiconductor catalyst may optionally be at least 0.01 mm / s, at least 0.02 mm / s, at least 0.05 mm / s, at least 0.1 mm / s, or at least 0.2 mm / s. The lateral speed of the polishing, grinding, rolling, or scratching tool on the surface of the semiconductor catalyst may optionally be a maximum of 10.0 mm / s, 5.0 mm / s, 2.0 mm / s, 1.0 mm / s, or 0.5 mm / s.

[0077] In some embodiments, indentation, polishing, grinding, rolling, scratching, or a combination of two or more of these is performed in one cycle or in multiple cycles totaling 100 or fewer cycles. The number of cycles may be, for example, 1 to 100, for example, 2 to 50, or 5 to 15. The number of cycles may be, for example, at least 1, for example, at least 2, or at least 5. The number of cycles may be arbitrarily up to 100, up to 50, or up to 15. [Examples]

[0078] 1. Introduction of transposition Rearrangements can be introduced into catalyst materials by various methods.

[0079] a) Macroscopic bulk deformation Uniaxial or biaxial deformation of bulk samples introduces dislocation arrangements from defined sliding systems. For this reason, several benchmaking tests are conducted under each uniaxial deformation. To this end, ordered dislocation structures were generated by uniaxial deformation of single crystals of BaTiO3 and TiO2 at high temperatures. These oxides are abundant functional ceramics and, consequently, low-cost materials.

[0080] Figure 3 shows a typical uniaxial stress-strain curve for deforming BaTiO3 at 1150°C to introduce a defined dislocation structure in a sliding system. The dislocation density increased by two to three orders of magnitude using this method.

[0081] b) Surface treatment Surface techniques were applied to both single-crystal and polycrystalline SrTiO3. Irregular surface dislocations were induced by polishing SrTiO3 at room temperature. These oxides are rich in functional ceramics and, consequently, low-cost materials. Surface treatment results in extremely high density; however, irregular dislocations are induced by either laterally movable or laterally static contact loads. Therefore, we employ surface grinding and polishing (movable contact) or indentation (static contact), such as surface Brinell ball indentation. Periodic indentation, in particular, has been found to be extremely effective in introducing dislocations into all types of ceramics, including polycrystalline materials. Continuous surface indentation, scratching, or rolling are highly scalable methods. These methods, provided the sample is sufficiently wide and the thickness of the compressed volume is in the 100 μm range, 2 Dislocations can be industrially introduced to surfaces within a range. The dislocation density is initially low, with a dislocation density of 10. 8 / m 2 ~10 10 / m 2 Compared to 10 13 / m 2 ~10 15 / m 2 This allows for a maximum increase of four or five digits.

[0082] 2. Visualization of dislocations A variety of techniques can be employed to investigate dislocations and their structures. Transmission electron microscopy has been shown to be effective in revealing distinguishable dislocation structures, specifically core and mesoscopic structures. Figure 18 shows a STEM image visualizing dislocations in (001) slice BTO from high-temperature deformation. 36 × 10 -12 m 2 There were 70 dislocations on the surface area. Therefore, the surface dislocation density was approximately 2 × 10⁻⁶. 12 m -2 That was the case.

[0083] To evaluate dislocation density, surface etching may be a further technique. Depending on the crystal orientation (or grains in polycrystalline materials), surface etching with acidic or alkaline solutions yields etching pit patterns. Around dislocations, chemicals have a more favorable effect on the surface. Therefore, dislocations are preferentially etched, leaving etching pits that can be observed under an optical microscope. For benchmark tests, the following etching techniques were used.

[0084] TiO2: The sample was immersed in 70% KOH buffer at 370°C for 4.5 minutes, followed by neutralization in 1 mol / l sulfuric acid for 1 minute.

[0085] SrTiO3: 15 drops of 50% HF aq Etching with 15 ml of 50% HNO. 3aq Medium. Approximately 1 minute.

[0086] A further method for investigating dislocations is electron channeling contrast imaging (ECCI). This is a scattering technique that uses the secondary beam of an electron microscope. Crystal defects such as dislocations or stacking faults can be visualized based on the various scattering behaviors of electrons in the vicinity of the defect. The advantage of this method is that it is non-destructive and does not require harmful etching techniques. Using electron backscatter diffraction (EBSD) techniques, we were able to access further information to consider dislocation density statistics and enable the characterization of lattice misorientations with respect to geometrically necessary dislocations (GNDs).

[0087] 3. Catalyst materials SrTiO3, TiO2, and BaTiO3 were used as benchmark examples. All samples had band gaps greater than 3 eV. The materials were deformed by uniaxial deformation or surface grinding.

[0088] The catalyst has a band gap E g The catalysts included semiconductor oxides and semiconductor sulfides in the range of 1.59 eV to 3.88 eV. These can absorb and utilize light in the wavelength range of 320 nm to 780 nm. The crystal structures of the catalysts include perovskite, quasi-perovskite, rutile, anatase, sphalerite, rock salt, fluorite, and spinel structures.

[0089] Figure 2 is a schematic diagram showing the investigated sample in which a dislocation was introduced. The size of the measured sample was 4 mm × 4 mm × 1 mm, and the total exposed reaction surface was 48 mm. 2 That was the case.

[0090] 4. Photocurrent generation under light irradiation A typical three-electrode configuration was used, with one platinum plate as the counter electrode and one Ag / AgCl electrode as the reference electrode. Samples with and without additionally introduced dislocations were used as working electrodes and immersed in a room-temperature electrolyte (0.5-5 M Na2SO4 electrolyte solution) with a pH of 6.5-7.5. A 300W Xe arc lamp (Beijing Perfect Light Technology Co., Ltd., China) was used to provide simulated sunlight in the wavelength range of 320 nm-780 nm. The setup is schematically shown in Figure 5.

[0091] The generated photocurrent was measured using a commercial electrochemical workstation (CHI760E, Shanghai Chenhua Instrument Ltd., China) over several on-off illumination cycles, along with the switching of the light on and off.

[0092] Figures 6–8 show the measured photocurrents (measurement setup shown in Figure 5) from catalyst samples with high / low dislocation densities introduced by uniaxial bulk deformation or surface indentation, for several on-off illumination cycles. The difference between high and low densities is 2–3 orders of magnitude for uniaxially deformed samples and 4–5 orders of magnitude for surface-treated samples. The low dislocation density represents the reference sample. High photocurrents indicate high photocatalytic activity. High photocatalytic activity is consistently associated with high dislocation density. This means that the photocurrent, and thus the photoelectrochemical conversion, can be increased by at least twofold for all oxide semiconductors used.

[0093] 5. Photocatalytic CO2 reduction The photocatalyst sample was transferred to a reactant solution contained in a reaction vessel with a volume of 4-500 ml. Pure CO2 gas (99.999%) was added to the solution and bubbled at a gas pressure of 101 kPa until CO2 saturation was reached to completely remove dissolved oxygen. The solution was then left in the dark for half an hour to reach adsorption-desorption equilibrium on the surface of the measured catalyst sample. Throughout the entire reaction, simulated sunlight in the wavelength range of 320 nm to 780 nm was supplied using a 300 W Xe arc lamp (Beijing Perfect Light Technology Co., Ltd., China). All tests were conducted in a sealed container at approximately 15°C using a water-cooling system. The reduction product was quantitatively analyzed by chromatography (GC9790, FuLi, China) equipped with both a thermal conductivity detector and a flame ionization detector.

[0094] The solution for photochemical CO2 reduction may contain bicarbonate or CO2 gas. Furthermore, sacrificial agents widely used in photocatalytic reduction (e.g., aliphatic amines, aromatic amines, and ascorbic acid) were added as electron donors to capture photogenerated holes.

[0095] Here, photocatalytic CO2 conversion was tested using three reactant systems. The first reactant system was a bicarbonate solution (NaHCO3) with CO2 gas bubbling inside, and triethanolamine was used as a sacrificial agent (Figures 9 and 10). The second reactant system was a bicarbonate solution (NaHCO3) without CO2 gas bubbling inside, and triethanolamine was used as a sacrificial agent (Figure 11). The third reactant system was deionized water with CO2 gas bubbling inside, and no sacrificial agent was used (Figure 12).

[0096] Using the evaluation method shown in the section below ("6. Quantitative Evaluation of CO2 Conversion Efficiency"), the photocatalytic CO2 conversion was evaluated for product yield (mol / m³). 2 The conversion was quantitatively evaluated by the carbon content ratio (%) of the product / reactant. CO2 conversion was illustrated by this method. This allows for the quantification of the effect of introduced rearrangements on the conversion efficiency.

[0097] Particularly relevant is the quantification of reactive organisms during development. Specifically, this invention focuses on the high yield of liquid carbon products and the low yield of gaseous products. These are quantified as described below, and cases with and without a translocation network are compared.

[0098] Figures 9 and 10 show the results of photocatalytic CO2 conversion from catalyst samples with high / low dislocation densities introduced by uniaxial deformation or surface treatment (grinding) indentation. A sample measuring 4 mm × 4 mm × 1 mm was used as the catalyst and placed in a 0.1 M, 50 ml NaHCO3 solution contained in a 100 ml reaction vessel. 5 ml of triethanolamine (99.9%, Aladdin Reagent Co., Ltd., Shanghai, China) was added to the reactant solution as a sacrificial agent. CO2 gas (99.999%) at a gas pressure of 101 kPa was bubbled into the solution until CO2 saturation was reached to completely remove dissolved oxygen. The solution was then left in the dark for half an hour to reach adsorption / desorption equilibrium on the surface of the measured catalyst sample. Throughout the entire reaction, simulated sunlight in the wavelength range of 320 nm to 780 nm was supplied using a 300 W Xe arc lamp (Perfect Light Technology Co., Ltd., Beijing, China). All tests were conducted in sealed containers at approximately 15°C using a water-cooling system. This allowed for attributing differences in reaction turnover to the effect of light rather than temperature. Reduction products were quantitatively analyzed at each time interval by chromatography (GC9790, FuLi, China).

[0099] At high rearrangement densities, the product yields of H2, CO, and CH3CHO after 8 hours of reaction are 5.9 mol / m³, respectively, as shown in Figures 9(a) and (b). 2 , 1.5 mol / m³ 2 , and 89.7 mol / m³ 2 The total CO2 conversion rate, which has a high rearrangement density, is approximately 72% after a reaction lasting 8 hours, and the main product is the liquid product acetaldehyde.

[0100] At low rearrangement densities, the product yields of H2, CO, and CH3CHO after 8 hours of reaction are 35.1 mol / m³, as shown in Figures 9(c) and (d). 2 , 6.2 mol / m³ 2 , and 40.6 mol / m³ 2 The total CO2 conversion rate with a high rearrangement density is approximately 35% after 8 hours of reaction, the production rate of the liquid product acetaldehyde is lower, and the production rates of H2 and CO are higher. In other words, roughly speaking, the CO2 conversion due to the introduced rearrangements is doubled (from approximately 35% to 72%), and the competing H2 production during CO2 reduction achieved by rearrangement introduction is reduced to one-sixth (35.1 mol / m³). 2 From 5.9 mol / m³ 2 This is suppressed. Both increased CO2 reduction and suppression of competing H2 production are beneficial for CO2 reduction.

[0101] The yield of CH3CHO after a 4-hour reaction is 81.88 mol / m³ at a high rearrangement density, as shown in Figure 10. 2 And in the case of a low dislocation density, it is 26.25 mol / m³. 2 The total CO2 conversion ratio was approximately 65% ​​at high rearrangement densities and approximately 21% at low rearrangement densities. As shown in Figure 9, although the reactants remained the same as those for BaTiO3, no gas products were detected. This indicates that the reaction pathway and product types differ for photocatalytic CO2 reduction with various ceramics. Figure 10 shows that when TiO2 was used as a catalyst, the CO2 conversion due to the introduced rearrangements improved by roughly three times (from approximately 21% to 65%).

[0102] Figure 11 shows the results of photocatalytic CO2 conversion from surface-treated SrTiO3 with high / low dislocation densities. In this case, the reaction solution consisted only of a 0.1M NaHCO3 solution (50 ml) contained in a 100 ml reaction vessel without bubbling CO2 gas inside. 5 ml of triethanolamine (99.9%, Aladdin Reagent Co., Ltd., Shanghai, China) was added to the reactant solution as a sacrificial agent.

[0103] The yield of CH3CHO after the 8-hour reaction was 22.53 mol / m³ at a high rearrangement density, as shown in Figure 11. 2 And in the case of a low dislocation density, it is 2.87 mol / m³. 2 The total CO2 conversion rate was approximately 43% at high dislocation densities and approximately 6% at low dislocation densities. No gas products were detected. This indicates that the CO2 conversion by the introduced dislocations improved by roughly seven times (from approximately 6% to 43%).

[0104] This means that by surface treatment to achieve the highest dislocation density, SrTiO3 exhibited a remarkable seven-fold increase in CO2 conversion based on the introduced dislocations. This can be explained by the fact that surface grinding results in a higher dislocation density compared to uniaxial deformation. While uniaxial deformation increases dislocation density by two to three orders of magnitude, surface grinding results in a dislocation density four to five orders of magnitude higher.

[0105] Figure 12 quantifies the results of photocatalytic CO2 conversion from uniaxially deformed TiO2 samples with high / low dislocation densities. In this case, the reaction solution consisted only of deionized water (10 ml) contained in a 100 ml reaction vessel with CO2 gas bubbling inside to a saturation level. Since no sacrificial agent was used, the conversion efficiency was lower compared to Figures 9-11, where a sacrificial agent was used.

[0106] For the standard test, 6.75 × 10 -3The same catalytic reaction was carried out for comparison by weighing g of rutile TiO2 powder (detailed estimation shown in the section below ("7. Quantitative Comparison with Powder Catalysts")). This is shown in Figure 12 with TiO2 powder.

[0107] The product yield of CO after a 7-hour reaction was 0.348 mol / m³ at a high rearrangement density. 2 For low dislocation densities, the rate is 0.024 mol / m³. 2 In contrast, no CO generation was detected in the case of chemical rutile TiO2 powder. The total CO2 conversion efficiency was approximately 0.39% at high dislocation density and approximately 0.027% at low dislocation density. This represents a roughly 15-fold (approximately 0.027% to 0.39%) increase in CO2 conversion due to the introduced dislocations.

[0108] 6. Quantitative evaluation of product yield and CO2 conversion efficiency Product yield is widely used to evaluate the photocatalytic CO2 reduction efficiency, quantifying the molar amount of product normalized by the weight of the catalyst during the reaction. However, the reaction mainly occurs on the surface of the catalyst. Here, the exposed surface area of ​​the sample measurement is employed to normalize the product yield to the measured catalytic reaction according to equation (1) below. The amount of product is quantitatively analyzed by chromatography, and the exposed reaction surface is 48 mm². 2 That was the interpretation.

[0109]

number

[0110] Alternatively, the CO2 conversion efficiency can also be evaluated by the carbon content ratio of the product / reactant. (CO2 / HCO3) -The molar amount n of carbon contained in the reactants can be calculated using the ideal gas law below. Here, P, V, and T are pressure, volume, and temperature, respectively, and R is the ideal gas constant. The pressure used for bubbling CO2 gas is 101 kPa, the temperature is 15°C (288 K), the solubility of CO2 gas in water at 288 K and a partial pressure of 1 atm is 101.9 ml CO2 per 100 ml of water, and R is 8.31 J / mol / K.

[0111]

number

[0112] The molar amount n of carbon contained in the product can be quantified from chromatographic analysis. Therefore, the CO2 conversion efficiency can be calculated.

[0113] 7. Quantitative comparison with powder catalysts Heterocatalytic reactions occur on the surface of the catalyst, where reactants are adsorbed. For comparison of powder catalyst samples, the specific surface area (SSA) can be determined by Brunauer-Emmett-Teller (BET) analysis. For example, in the case of the BaTiO3 powder used (99.9%, from Aladdin Reagent Co., Ltd. in Shanghai, China), this is 25.96 m². 2 It is / g. Therefore, roughly speaking, it is 1.85 × 10 -6 g of BaTiO3 powder was the same size as the measured sample, which was 4 mm x 4 mm x 1 mm, and measured 48 mm. 2 It can be estimated that it has an exposed reactive surface. In actual tests, this 1.85 × 10 -6 The weight in grams cannot be controlled at a laboratory scale. For comparative testing, 1.85 × 10 -3The same catalytic reaction was carried out by first weighing g (1000 times the estimated weight) of BaTiO3 powder, and then the yield was divided by 1000 for comparison. A similar comparison was applied to TiO2 catalyst samples with rearrangements. Here, titanium rutile oxide (99.99%, Aladdin Reagent Co., Ltd., Shanghai, China) was weighed and used for comparison. The measured SSA of the titanium rutile oxide powder was 7.11 m from BET analysis. 2 It was / g. Roughly speaking, this means 6.75 x 10 -6 g of TiO2 powder, 48 mm 2 Since it has an exposed reaction surface, 6.75 x 10 -3 Weighing g of TiO2 indicates that the standard test was performed.

[0114] 8. Photocatalytic H2O2 Production Each type of material, measuring 4mm x 4mm x 1mm, was placed in 20ml of deionized water and used as a catalyst by bubbling air or pure O2 until the gas saturated. No sacrificial agent was used. Artificial sunlight was supplied using a Xe arc lamp. The generated H2O2 was quantitatively detected using a colorimetric DPD method based on the horseradish peroxidase (POD) catalyzed oxidation of N,N-diethyl-p-phenylenediamine (DPD).

[0115] According to Figures 13, 14, and 16, based on the H2O2 yield, it could be concluded that the introduced rearrangement resulted in a roughly twofold improvement in photocatalytic H2O2 production. As shown in Figures 15 and 17, the stability of the photocatalyst was determined by conducting a cycle test over five cycles. As shown in Figures 14 and 16, for the baseline test, 1.85 x 10⁻¹⁰ -3 g of BaTiO3 powder and 6.75 x 10 -3 The same reaction was performed for comparison by weighing rutile TiO2 powder. With some powder reference samples, H2O2 was not produced.

Claims

1. A photocatalytic reduction method for a reactant, wherein the method is a) A step of preparing a setup including a photocatalyst immersed in an aqueous solution containing the reactant, b) A step of irradiating the photocatalyst with light, The method is characterized in that the photocatalyst includes a semiconductor photocatalyst containing dislocations, or consists of a semiconductor photocatalyst containing dislocations, and the surface dislocation density on at least a portion of the surface of the photocatalyst is at least 1.0 × 10 １１ I understand －２ A photocatalytic reduction method for a reactant, characterized by the following:

2. The reactant is CO ２ / HCO ３ － / CO ３ ２－ or O ２ The method according to claim 1, including the method described in claim 1.

3. The method according to claim 1 or 2, wherein the light includes electromagnetic radiation having a wavelength of 320 nm to 780 nm.

4. The method according to any one of claims 1 to 3, wherein the photocatalyst is a ceramic.

5. The method according to any one of claims 1 to 4, wherein the photocatalyst is a polycrystalline ceramic.

6. The surface dislocation density is at least 1.0×10 １２ m －２ The method according to any one of claims 1 to 5.

7. The reactant is O ２ And the product obtained by the reduction of the reactants is H ２ O ２ The method according to any one of claims 1 to 6, including the method described in any one of claims 1 to 6.

8. The reactant is CO ２ / HCO ３ － / CO ３ ２－ It contains, and the product obtained by the reduction of the reactants is CO, CH ４ ,CH ２ O, CH ３ OH, CH ３ CHO, CH ３ CH ２ The method according to any one of claims 1 to 6, comprising OH, or a combination of two or three or more of these.

9. The method according to any one of claims 1 to 8, wherein the molar ratio of the liquid product to the gaseous product is at least 1:

1.

10. The method according to any one of claims 1 to 9, wherein the conversion efficiency is at least 50%.

11. The method according to any one of claims 1 to 10, wherein the light source for irradiating the photocatalytic working electrode is a Xe arc lamp.

12. The method according to any one of claims 1 to 11, wherein the aqueous solution comprises at least one sacrificial agent.

13. The method according to any one of claims 1 to 12, wherein the method includes the step of introducing the reactant into the aqueous solution as bubbles.

14. The method according to any one of claims 1 to 13, wherein the pH of the aqueous solution is 6.0 to 8.

0.

15. The method according to any one of claims 1 to 14, wherein the aqueous solution is deionized water.

16. The method according to any one of claims 1 to 14, wherein the aqueous solution contains one or more inorganic salts in an amount of at least 100 mM.

17. The method according to any one of claims 1 to 16, wherein the method is carried out at a temperature of 10°C to 30°C.

18. The method according to any one of claims 1 to 17, wherein the photocatalyst has a conduction band on the negative side of 0.68 V and / or a valence band on the positive side of 1.76 V.

19. The photocatalyst is BaTiO ３ SrTiO ３ , or TiO ２ The method according to any one of claims 1 to 18.

20. The method according to any one of claims 1 to 19, wherein the photocatalyst is irradiated with light such that the photocatalyst-reactant interface near or at the dislocation acts as a reaction site for the photocatalytic reaction.

21. The method according to any one of claims 1 to 20, further comprising the step of separating the liquid organic product from the gaseous product.

22. The method according to any one of claims 1 to 21, wherein the setup is an electrochemical setup and the photocatalyst is a photocatalytic working electrode.

23. The method according to claim 22, wherein the electrochemical setup further includes a counter electrode.

24. The method according to claim 22 or 23, wherein the electrochemical setup further includes a reference electrode.

25. The method according to any one of claims 22 to 24, wherein the electrochemical setup further comprises an electrochemical workstation.

26. A setup comprising a semiconductor photocatalyst containing dislocations, or a photocatalyst consisting of a semiconductor photocatalyst containing dislocations, wherein the surface dislocation density is at least 1.0 × 10 １１ I understand －２ That is the setup.

27. The setup according to claim 26, wherein the photocatalyst is a ceramic.

28. The setup according to claim 26 or 27, wherein the photocatalyst is a polycrystalline ceramic.

29. The surface dislocation density is at least 1.0 × 10 １２ I understand －２ The setup according to any one of claims 26 to 28.

30. The setup according to any one of claims 26 to 29, wherein the setup includes a light source configured to irradiate a photocatalyst.

31. The setup according to claim 30, wherein the light source is a Xe arc lamp.

32. The setup according to any one of claims 26 to 31, wherein the photocatalyst has a conduction band on the negative side of 0.68 V and / or a valence band on the positive side of 1.76 V.

33. The photocatalyst is BaTiO ３ SrTiO ３ , or TiO ２ The setup according to any one of claims 26 to 32, comprising:

34. The setup according to any one of claims 26 to 33, wherein the setup is an electrochemical setup and the photocatalyst is a photocatalytic working electrode.

35. The setup according to claim 34, wherein the electrochemical setup further includes a counter electrode.

36. The setup according to claim 34 or 35, wherein the electrochemical setup further includes a reference electrode.

37. The setup according to any one of claims 34 to 36, further comprising an electrochemical workstation.

38. A method for photocatalytic reduction of a reactant, particularly the method according to any one of claims 1 to 25, using the setup described in any one of claims 26 to 37.

39. The surface dislocation density is at least 1.0 × 10⁻⁶ １１ I understand －２ Use of semiconductor photocatalysts containing dislocations as a photocatalyst or in photocatalysis.

40. The use according to claim 39, wherein the photocatalyst is used in a photocatalytic reduction method for a reactant, particularly in the method according to any one of claims 1 to 25.

41. The surface dislocation density is at least 1.0 × 10⁻⁶ １１ I understand －２ A method for preparing a semiconductor photocatalyst containing a dislocation, the method comprising the following steps: - Uniaxial or biaxial deformation of semiconductor photocatalysts, - Surface treatment of a semiconductor photocatalyst, wherein the surface treatment includes indentation, polishing, grinding, rolling, scratching, or a combination of two or more of these. A method for preparing a semiconductor photocatalyst comprising one or more of the following.

42. The method according to claim 41, wherein the uniaxial or biaxial deformation includes a plastic deformation of at least 0.5% and / or up to 30%.

43. The method according to claim 41 or 42, wherein the uniaxial or biaxial deformation is performed at a temperature ranging from room temperature to 1000°C.

44. The method according to any one of claims 41 to 43, wherein the uniaxial or biaxial deformation is a uniaxial or biaxial macro deformation.

45. The method according to any one of claims 41 to 44, wherein the unaxial or biaxial deformation is performed under load control or displacement control.

46. The method according to any one of claims 41 to 45, wherein the surface treatment includes indentation, and the load on the indenter is 1.0 N to 100 N.

47. The method according to any one of claims 41 to 46, wherein the surface treatment includes indentation, and the contact zone between the indenter and the semiconductor photocatalyst is 100 μm to 1.0 mm.

48. The surface treatment includes indentation, and the material of the indenter is hardened steel, SiC, Si ３ N ４ , ZrO ２ The method according to any one of claims 41 to 47, comprising a material selected from the group consisting of two or more combinations thereof.

49. The method according to any one of claims 41 to 48, wherein the surface treatment comprises polishing, grinding, rolling, scratching, or a combination of two or more of these, and the lateral speed of the polishing, grinding, rolling, or scratching tool on the surface of the semiconductor catalyst is 0.01 mm / s to 10 mm / s.

50. The method according to any one of claims 41 to 49, wherein indentation, polishing, grinding, rolling, scratching, or a combination of two or more of these is performed in one cycle or in multiple cycles totaling 100 or less.

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