TWI672176B - Photocatalytic material structure with heterointerface formed on substrate - Google Patents

Abstract

The invention relates to a structure for improving the photocatalytic ability of a heterostructure by means of interface doping, mainly in the process of preparing a heterostructure film, by doping in the interface region: performing p-doping in a region with a material having low electron affinity Or, in the region with high electron affinity, the n-type doping is performed to form a heterostructure film with proper doping. Compared with the conventional undoped heterostructure, the structural film with appropriate interface doping has High light catalytic ability.

Description

Photocatalytic material structure with heterointerface formed on substrate

The present invention relates to a material structure that utilizes a region doping method to enhance the photocatalytic ability of the heterostructure in a heterostructure.

The photocatalytic method is a technique for decomposing molecules under irradiation of a light source. In the application of organic pollutants in the removal of water, the photocatalytic material is often placed in water contaminated by organic matter, and under the illumination of the light source, oxidation and reduction reactions are carried out on the surface of the photocatalytic material, and the organic pollutants are decomposed to reach a clean water source. the goal of.

On the catalytic material, an oxide such as titanium oxide TiO ₂ , zinc oxide ZnO, tin oxide SnO ₂ or the like is often used. These materials are converted into electron-holes after absorbing photons. When these electron-holes move to the surface of the material, the end of the hole undergoes an oxidation reaction and a reduction reaction at the electron end, and the organic matter in the water is decomposed to achieve the purpose of removing organic matter.

U.S. Patent Publication No. US20120097522A1, which discloses the use of zinc nitrate to react with cyclohexylamine to form polyhedral particulate ZnO in water or ethanol solution. And under the irradiation of light, the granular ZnO is used to decompose the cyanide in the aqueous solution to achieve the purpose of purifying the water.

In addition to the use of a single material, two (or more) materials can be combined to enhance their catalytic capabilities. U.S. Patent Publication No. US20050008549A1, which discloses the use of TiO ₂ , ZnO, SnO ₂ , SrTiO ₃ , WO ₃ , Bi ₂ O ₃ and Fe ₂ O ₃ as a base material, and the mixing of these base materials to enhance Photocatalytic ability.

Reference is made to U.S. Patent No. 6,274,049, which discloses a photocatalytic device comprising a filter structure in addition to a catalytic material and a light source. To prevent the particulate catalytic material from being discharged during the reaction.

For the sake of his position, the applicant conducted experiments and research to propose a structure that enhances the photocatalytic reaction, especially for the heterostructure combining the two materials, and appropriately doping at the interface to enhance the heterostructure. The efficacy of photocatalytic ability.

In view of this, the inventors have, in view of the rich experience in design and development and actual production of the relevant industries for many years, researched and improved the existing technologies and defects, and provided a photocatalytic material structure with a heterogeneous interface made on a substrate. In order to achieve better practical value.

In view of the above-mentioned prior art, the main object of the present invention is to provide a photocatalytic material structure having a hetero interface formed on a substrate, and performing appropriate doping at the interface to achieve the effect of improving the photocatalytic ability of the heterostructure.

In order to achieve the above object, the present invention provides a photocatalytic material structure having a hetero interface formed on a substrate, comprising: a substrate material; a material which is a material having low electron affinity; and a second material which is a material having high electron affinity and is formed on the substrate material in combination with the first material; wherein the first material is adjacent to the second material a material region, performing p-doping in an interface region; or the second material is n-doped in an interface region near the material end of the first material; or simultaneously having p-doping in the interface region An n-type doped structural material in the interface region.

Preferably, the first material and the second material may be selected from a semiconductor material, a polymer material, an organic material, or a combination thereof.

Preferably, the substrate material may be selected from the group consisting of ruthenium, aluminum, iron, nickel, zinc oxide, molybdenum oxide, tin oxide, aluminum oxide, nickel oxide, copper oxide, or a combination thereof.

Preferably, the first material and the second material may be selected from the group consisting of zinc oxide, molybdenum oxide, tin oxide, aluminum oxide, nickel oxide, copper oxide or a combination thereof.

Preferably, the p-doping of the interface region and the n-doped material of the interface region may be selected from the group consisting of nitrogen, arsenic, antimony, iron, chlorine, bromine, antimony or a combination thereof.

Preferably, the first material, the second material and the doping method may be selected from the group consisting of spray coating, thermal evaporation, electron beam evaporation, sputtering, vapor deposition, liquid deposition, or a combination thereof.

According to another feature of the invention, it can be synthesized on a substrate such as a metal, a semiconductor, or a polymer to form the structure.

The present invention constitutes a heterostructure by bonding two materials whose electron affinities differ from each other. On the side of small electron affinity, rely on The near junction region is p-doped, or the electron affinity is large, the n-type doping is performed close to the junction region, or the composition of the two, thereby improving the photocatalytic ability of the heterostructure.

The above summary and the following detailed description and drawings are intended to further illustrate the manner, means and effects of the present invention in achieving its intended purpose. Other purposes and advantages of this creation will be explained in the following description and drawings.

100‧‧‧Substrate material

110‧‧‧First material

111, 121‧‧‧ structural layer

120‧‧‧Second material

E‧‧‧Electronic affinity

h(a), h(b)‧‧‧ holes

e(a), e(b)‧‧‧Electronics

C‧‧‧ concentration

t‧‧‧Time

A‧‧‧ before improvement

b‧‧‧After improvement

1 is a schematic diagram of a two-layer structure on a substrate; FIG. 2 is a schematic diagram of a zinc oxide-molybdenum oxide band; and FIG. 3 is a relationship between a concentration of a remaining Congo red solution and a reaction time under a photocatalytic reaction. Figure. It includes (a) the results before the improvement and (b) the improvement; the fourth figure is a schematic diagram of the two-layer structure after the improvement of the electron affinity, and the fifth figure is the improvement of the one with the greater electron affinity. Schematic diagram of the double layer structure.

Fig. 6 is a schematic diagram of a two-layer structure which is improved simultaneously with a large electron affinity and a small electron affinity.

The embodiments of the present invention are described below by way of specific examples, and those skilled in the art can understand the other advantages and advantages of the present invention from the disclosure.

Please refer to FIG. 1 , which is a schematic diagram of a two-layer photocatalytic material on a substrate. As shown, the structure includes a substrate material 100, wherein the substrate material 100 can be selected from the group consisting of ruthenium, aluminum, iron, nickel, zinc oxide, molybdenum oxide, tin oxide, aluminum oxide, nickel oxide, copper oxide, or a combination thereof. And then using the first material 110 and the second material 120 on the substrate material 100 by evaporation, sputtering, chemical vapor, spraying, immersion, or the like, wherein the first material 110 and the first material 110 The second material 120 can be selected from a semiconductor material, a polymeric material, or a combination thereof, such as zinc oxide, molybdenum oxide, tin oxide, aluminum oxide, nickel oxide, copper oxide, or a combination thereof. In the present embodiment, the substrate material 100 is an n-type germanium substrate. The first material 110 is zinc oxide (ZnO) and the second material 120 is molybdenum oxide (MoO ₃ ). The first material 110 and the second material 120 are formed by a spray pyrolysis method in which zinc acetate and an aqueous solution of molybdenum chloride are used as precursors, and are sequentially sprayed at 450 ° C. The thickness is in the order of 450 nm and 120 nm.

2 is an energy band diagram of the first material 110 and the second material 120. Since the energy gap (about) of zinc oxide and molybdenum oxide is 3.3 eV and 3.0 eV, respectively, the electron affinity E (about) of molybdenum oxide is 6.4 eV, which is higher than the electron affinity E (about) of 4.3 eV of zinc oxide. Therefore, the interface energy band is discontinuous. When lighting, both areas are An electron-hole is generated, and the difference in the band causes the electron and the hole to move separately. Finally, the hole h(b) of the second material 120 (molybdenum oxide) region participates in the oxidation reaction in the solution, and the electron e(a) in the first material 110 (zinc oxide) region participates in the reduction reaction in the solution. In the present embodiment, a Congo red dye which is commonly used in the textile, printing, and pharmaceutical industries is selected as the substance to be removed. The zinc oxide/molybdenum oxide structural film was used as a photocatalytic material, and a low-pressure mercury lamp having a light source of 20 W was irradiated to carry out photocatalytic decomposition of a Congo red aqueous solution having a concentration of 50 ppm. The relationship between the residual concentration C of Congo red and the time t during the reaction is shown in Figure 3, before the improvement a: after 80 minutes of reaction, the concentration of Congo red in the solution drops to 15 ppm, indicating that the material is in the Congo in aqueous solution. Red has considerable decomposing power.

In the structure of Figure 1, there are quite a few factors for a smooth response. In the diagram of Fig. 2, in consideration of the movement of electrons and holes, in addition to the electrons e(a) and holes h(b) can smoothly move to the surface, if the two materials interface electronic e(b) and electricity If the hole h(a) cannot be recombined smoothly, the existence of the electron e(b) affects the ability of the hole h(b) to move to the right surface; and the presence of the hole h(a) affects the movement of the electron e(a) to The ability of the left surface. Therefore, whether the electron e(b) and the hole h(a) can be smoothly combined is an important factor affecting the photocatalytic ability of the structure.

In order to improve the above disadvantages and improve the smooth recombination of the electrons e(b) and the holes h(a), please refer to FIG. 4, and above the first material 110 structure, a layer of the same material as the first material 110 is fabricated. , but is a p-doped structural layer 111 of the interface region, wherein the p-doped material of the interface region is selected from the group consisting of nitrogen, arsenic, antimony, iron, chlorine, bromine, antimony or a combination thereof, so that the second diagram can be promoted. The valence band at the end of the first material 110 is further bent upwards, which enhances the ability of the hole h(a) to move to the interface. In an improved embodiment, the undoped first material 110 has a zinc oxide layer having a thickness of 360 nm, and the nitrogen-doped zinc oxide (ZnO: N) is a p-doped structural layer 111 having an interfacial region having a thickness of 90 nm. The p-type concentration is 2x10 ¹⁷ cm ^-3 . The rest of the structure and parameters are unchanged.

The same photocatalytic step as described above was carried out with this material, and the normalized concentration C-time t relationship of Congo red was as shown in the modified b of Fig. 3: after 80 minutes of reaction, the Congo red concentration in the solution was lowered. 11 ppm, which enhances the ability to decompose Congo red in aqueous solution.

The above-described embodiments are merely illustrative of the features and functions of the present invention, and are not intended to limit the scope of the technical scope of the present invention. According to the spirit of the present invention, n-type doping can also be applied to the side having a large electron affinity: as shown in Fig. 5. The n-doped structural layer 121 of the interface region is the same high electron affinity material as the second material 120, and the n-type doping is applied to the structural layer 121, wherein the n-doped material in the interface region is selected from nitrogen and arsenic. , ruthenium, iron, chlorine, bromine, ruthenium or a combination of the above, can increase the electron e(b) movement of Figure 2 to the interface capacity, and contribute to the reaction with the hole h(a), resulting in the same as Figure 4. The effect.

In addition, referring to FIG. 6, the present invention can simultaneously have the structural material of the interface region p-type doped structure layer 111 and the interface region n-type doped structure layer 121. Modifications and variations of the above-described embodiments can be made by those skilled in the art without departing from the spirit and scope of the invention. Therefore, the scope of protection of the present invention should be as set forth in the scope of the claims described below.

The first material 110, the second material 120 and the doping method of the above embodiment may be selected from the group consisting of spray coating, thermal evaporation, electron beam evaporation, sputtering, vapor deposition, liquid deposition, or a combination thereof.

In summary, the present invention is mainly used in the process of preparing a heterostructure film by doping the interface region: a region p-type doping with a material having a low electron affinity, or/and a material having a high electron affinity The region is n-doped to form a properly doped heterostructure film, which has a higher photocatalytic ability than a conventional undoped heterostructure.

The above-described embodiments are merely illustrative of the features and functions of the present invention, and are not intended to limit the scope of the technical scope of the present invention. Modifications and variations of the above-described embodiments can be made by those skilled in the art without departing from the spirit and scope of the invention. Therefore, the scope of protection of the present invention should be as set forth in the scope of the claims described below.

Claims (4)

A photocatalytic material structure having a hetero interface formed on a substrate, comprising: a substrate material; a first material being a zinc oxide material and formed on the substrate material; and a second material being molybdenum oxide a material formed on the first material; wherein the first material is p-doped in an interface region near a material end of the second material; or the second material is near a material end of the first material, An n-type doping of the interface region is performed. The photocatalytic material structure according to claim 1, wherein the substrate material is selected from the group consisting of ruthenium, aluminum, iron, nickel, zinc oxide, molybdenum oxide, tin oxide, aluminum oxide, nickel oxide, copper oxide or the like. combination. The photocatalytic material structure according to claim 1, wherein the p-doping of the interface region and the n-doping of the interface region are selected from the group consisting of nitrogen, arsenic, antimony, iron, chlorine, bromine, antimony or Combination of the above. The photocatalytic material structure according to claim 1, wherein the first material, the second material and the doping method are selected from the group consisting of spray coating, thermal evaporation, electron beam evaporation, sputtering, and gas. Phase deposition, liquid deposition or a combination of the above.