• 专利附录
  • 专利说明
  • 权利要求
  • 类似技术
  • 同族专利
  • 引用文献
  • 法律状态
  • 优先权
    • 专利摘要:
    Use of nanoparticles with highly efficient photoelectrocatalytic activity. Obtaining core-shell type morphologies formed by transition metal carbides-oxides produces a synergistic effect to avoid electron/hole recombination processes, increase electrical conductivity and electrocatalytic and photoelectrocatalytic activity. Thus, the photoelectrocatalytic yield that they present towards different photoelectrochemical reactions of interest is increased, such as the generation of hydrogen, reduction of carbon dioxide and nitrate. (Machine-translation by Google Translate, not legally binding)
    公开号:ES2862426A1
    申请号:ES202000050
    申请日:2020-04-06
    公开日:2021-10-07
    发明作者:Silvestro Gonzalo Garcia；Tejera Elena María Pastor；Coello Sergio Diaz；Sunga Maximina Luis
    申请人:Universidad de La Laguna；
    IPC主号:
    专利说明:

    [0002] Highly efficient nanomaterials
    [0004] Technical sector
    [0006] The following invention is part of the nanotechnology and materials science sector.
    [0008] Background of the invention
    [0010] Recently, photoelectrochemical processes have acquired special relevance in the field of renewable energies. This is because, in electrochemical energy conversion devices, such as fuel cells and electrolyzers, it is possible to decrease the amount of energy required to carry out electrochemical reactions by absorbing photons of light. Thus, it has been shown that when a photon of light hits the surface of a semiconductor, an electron (with a negative formal charge) and a hole (with a positive formal charge) are released. After the formation of the electron / hole pair, both must migrate to different areas of the material to produce the pair of electrochemical reactions of interest [1], [2].
    [0012] However, the materials (semiconductors) used as catalysts in this type of technology have several drawbacks that reduce the effectiveness of the devices where it is necessary to convert energy into chemicals of interest: i) low electrocatalytic activity towards the reactions of interest; ii) low electrical conductivity; and iii) loss of photocatalytic and / or photosensitizing activity due to recombination processes of charge carriers (electron / hole). In this last process, the electron / hole pairs formed by the previously explained mechanism can be re-combined inside the material, without producing the reactions of interest [1] - [3].
    [0014] Explanation of the invention
    [0016] The present invention discloses the use of transition metal nanomaterials with a core-shell structure that solve the drawbacks described above (i, ii and iii), due to the fact that they develop: i) high electrical conductivity, ii) high electrocatalytic activity towards the reactions of interest and iii) high photocatalytic activity to generate the parelectron / hole with no or low recombination of the same in a wide range of wavelengths (UV and visible).
    [0018] The solution reached consists of synthesizing nanoparticles of transition metal compounds (carbides and oxides) with core-shell morphology. Through the proposed methodology, materials of this type can be obtained, where the core is formed by transition metal carbide phases (groups 3 to 12 and periods 4 to 7 of the periodic table) while the shell is formed by different oxides of the same transition metal, as shown in Figure 1.
    [0020] To obtain these nanoparticles with the desired core-shell morphology, several synthesis routes can be carried out with the ability to control both the physicochemical properties (chemical nature, crystalline phases, size, etc.) of the core and shell, as well as the optoelectronic properties of the shell. nanomaterial (Figures 2 and 3) [4] - [6].
    [0022] Thanks to the formation of nanoparticles with core-shell morphology, it is possible to minimize (or cancel) the recombination effect of the electron / hole pairs (Figure 4) where the Synergy between the physicochemical properties of the chemical phases obtained in the material appears as one of the main characteristics to avoid the processes described due to the formation of the shell of semiconductor oxides of the order of nanometers thick. The core, made up of transition metal carbides, provides a good electrical conductivity to the material as well as an excellent electrocatalytic activity towards the reaction of interest [7]. This catalytic activity has been shown to be due to transition metal carbides having an electronic structure similar to that of the platinum group (PGM) near the Fermi level [8]. For this reason, similar interest reaction performances are expected from these nanomaterials.
    [0024] The shell, formed by the oxide of the same transition metal from which the core is formed, provides the photosensitizing capacity of the material due to the semiconductor properties of said chemical phase. Furthermore, this oxide semiconductor phase is a few nanometers thick. Due to this, the electrons and holes generated in the shell can more easily migrate to the reaction sites, so that recombination processes are minimized or canceled.
    [0026] Due to these characteristics, it is concluded that the processes observed in this type of materials greatly improve the performance, and, therefore, the photoelectrochemical efficiency towards the reactions of interest. Furthermore, due to the low cost of the starting reagents, it is understood that the materials obtained are considered as low-cost catalysts, which can also be obtained by means of routine synthetic steps and processes.
    [0028] References
    [0030] [1] DA Neamen, Semiconductor Physics and Devices Basic Principles. 2006.
    [0032] [2] S. Ghosh, R. Vasant Kumar, and M. Coto, "Visible-Light-Active Photocatalysis:
    [0033] Nanostructured Catalyst Design, Mechanisms, and Applications, ”in Visible Light-Active Photocataiysis , 2018.
    [0035] [3] P. Salvador and C. Gutiérrez, "Analysis of the transient photocurrent-time behavior of a sintered n-SrTiO3 electrode in water photoelectrolysis," J. Electroanal. Chem., Vol. 160, no. 1-2, pp 117-130, 1984.
    [0037] [4] G. García, M. Roca-Ayats, O. Guillén-Villafuerte, J. L. Rodríguez, C. Arévalo, and E.
    [0038] Pastor, “Electrochemical performance of a-Mo2C as catalyst for the hydrogen evolution reaction,” J. Electroanal. Chem., Vol. 793, pp. 235-241,2017.
    [0040] [5] C. Giordano, C. Erpen, W. Yao, and M. Antonietti, "Synthesis of Mo and W Carbide and Nitride Nanoparticles via a Simple 'Urea Glass'Route," Nano Lett., Vol. 8, no. 12, pp.
    [0041] 4659-4663, Dec. 2008.
    [0043] [6] G. García, O. Guillén-Villafuerte, JL Rodríguez, MC Arévalo, and E. Pastor, "Electrocatalysis on metal carbide materials,” Int. J. Hydrogen Energy, vol. 41, no. 43, pp. 19664 -19673, 2016.
    [0045] [7] Y. Liu, TG Kelly, JG Chen, and WE Mustain, "Metal carbides as alternative electrocatalyst supports," ACS Catal., Vol. 3, no. 6, pp. 1184-1194, 2013.
    [0046] [8] Y. Liu, TG Kelly, JG Chen, and WE Mustain, "Metal carbides as alternative electrocatalyst supports," ACS Catal., Vol. 3, no. 6, pp. 1184-1194, 2013.
    [0047] Brief description of the drawings
    [0048] To complement the description that is being made and in order to help a better understanding of the characteristics of the invention, a set of drawings is attached as an integral part of said description, in which, with an illustrative and non-limiting nature, the following has been represented. following:
    [0049] Figure 1. Diagram of the type of synthesized nanoparticle where (1) is the shell with photosensitizing properties formed by transition metal oxides and (2) is the electrocatalytic nucleus of the nanoparticle formed by transition metal carbides (left image). On the right side of the figure you can see a transmission electron microscopy (TEM) image of a synthesized nanoparticle where the core (2) made up of transition metal carbide (Mo2C) and the shell (1) made up of transition metal oxides (MoOx).
    [0050] Figure 2. X-ray photoelectron spectroscopy (XPS) revealing the surface of the nanomaterial composed of transition metal oxides (MoOx).
    [0051] Figure 3. X-ray diffraction (XRD) indicating the crystalline structure of the transition carbide nucleus (Mo2C).
    [0052] Figure 4. Current transient showing the theoretical behavior of a semiconductor in the presence (On) and absence (Off) of light (a). Current transient associated with the generation of molecular hydrogen on the synthesized Mo2C nanoparticles obtained at -0.20 V (vs reversible hydrogen electrode (ERH) in 0.1 M sodium hydroxide in presence (On) and absence (Off) of sunlight (AM1.5G; 7.6 mW-cm-2 Geometric area = 0.785 cm2) (b). 1: Photocurrent generated due to the action of light; and 2: Loss of current due to recombination phenomena of the charge carriers (hole and electron).
    [0053] Figure 5. Increase in the crystallite size of the Mo2C nucleus with increasing time in carbothermal synthesis at 800 ° C.
    [0054] Figure 6. UV-Visible absorption spectra of different Mo2C dispersions in ethanol and Tauc diagram indicating the band gap energy which is close to 2.9 eV (b).
    [0055] Figure 7. Photocurrent associated with the generation of molecular hydrogen on Mo2C nanoparticles (obtained at different times of carbothermic synthesis at 800 ° C) at -0.24 V vs ERH in 0.1 M sodium hydroxide.
    [0056] Figure 8. Current transients associated with the generation of molecular hydrogen on commercial Mo2C particles (black line) obtained at -0.42 V vs RHE and on synthesized Mo2C nanoparticles (gray line) obtained at -0.24 V vs RHE in 0.5 M sulfuric acid in the presence (On) and absence (Off) of sunlight (AM1.5G; 7.6 mW-cm-2). Figure 9. Current transients associated with the electroreduction of carbon dioxide on synthesized Mo2C nanoparticles obtained at -0.10 V vs RHE in 0.5 M sulfuric acid in the presence (ON) and absence (OFF) of sunlight (AM1 .5G; 7.6 mW-cm -2).
    [0057] Figure 10. Current transients associated with the electroreduction of nitrate on synthesized Mo2Ü nanoparticles obtained at -0.10 V vs RHE in 0.5 M sulfuric acid, 0.1 M potassium nitrate in the presence (ON) and absence (OFF) sunlight (AM1.5G; 7.6 mW-cm -2).
    [0059] Implementation of the invention
    [0061] In a first embodiment of the invention, the photoelectrocatalytic activity of molybdenum carbide core nanoparticles (Mo2Ü) with a coating of molybdenum oxide (MoOx) synthesized by a carbothermic method for molecular hydrogen generation reactions is shown.
    [0063] First, a nanoparticle precursor is synthesized from a solution of 1.8 g of molybdenum (IV) oxide in 30 ml of 30% v / v ammonia. On the other hand, 0.15 g of carbon black is dispersed in absolute ethanol by ultrasound. The carbon black solution is added to the molybdenum oxide solution dropwise while maintaining continuous stirring. Later it is taken to dryness at 60 ° C, obtaining the precursor. The above product must be brought from room temperature to 800 ° C in a tubular oven at a heating rate of 5 ° C / min, leaving the product at different times of the maximum temperature to obtain different sizes of crystallite. This procedure is carried out under the flow of a mixture of H2 / N2 gas at 5% v / v in hydrogen, programming a flow of the gas mixture through the tubular oven of 140 ml / min.
    [0065] This synthesis gives rise to nanoparticles with the morphology explained above, where the particle size is between 10 - 60 nm (depending on the time at maximum temperature, see Figure 5), which are characterized by being formed by a crystalline nucleus of molybdenum carbide (Mo2C; see Figure 3), and a coating of amorphous phases of different molybdenum oxides (see Figure 2).
    [0067] The photoelectrocatalytic activity of the nanoparticles has been verified. For this, a three-electrode cell has been used, using a reversible hydrogen electrode (ERH) as a reference and a glassy carbon counter electrode. The working electrode used was a 20 pL deposit of the catalytic ink on a glassy carbon disk electrode (geometric area = 0.785 cm2). The catalytic ink consists of 4 mg of the synthesized material, 500 pL of ultra pure water and 15 pL of Nafion®. Figure 4b shows the yield of molybdenum carbide (Mo2C) towards the hydrogen evolution reaction (photoelectrochemical generation reaction of hydrogen gas from an aqueous solution at pH = 13, using NaOH as background electrolyte). Figure 8 shows the performance of molybdenum carbide (Mo2C) towards the hydrogen evolution reaction in an aqueous solution at pH = 1 , using sulfuric acid as a background electrolyte. The cell has a quartz window, through which the surface of the working electrode is illuminated with a xenon lamp that is equipped with an AM1.5G sunlight simulating filter programmed to illuminate with an irradiance of 7.6 mW -cm-2. Figures 4b and 8 show the behavior of the nanoparticles when illuminated with sunlight at a constant potential. Thus, when the surface is illuminated, a photocurrent (1) is obtained, which when time passes, reaches a constant value in which no losses are observed due to electron / hole recombination processes, such as those observed in the theoretical behavior of Figure 4A.
    [0069] In another embodiment of the invention, the photoelectrocatalytic activity of the synthesized nanoparticles in carbon dioxide reduction reactions is shown in Figure 9. For this, a configuration analogous to the previous case has been used, performing the I experiment in a 0.5 M sulfuric acid solution (pH = 1) saturated with carbon dioxide (CO2). In Figure 9 it can be seen how when the sample is illuminated with simulated sunlight, a photocurrent is obtained, which, as in the case of the photoelectrochemical generation of hydrogen, remains constant over time, indicating that for The reduction of carbon dioxide reduction is also not observed photocurrent losses due to electron / hole recombination processes.
    [0071] In a third embodiment, the photoelectrocatalytic activity of the synthesized nanoparticles in the reduction of nitrate is demonstrated, as shown in Figure 10. In this way, in the same electrochemical cell configuration of the previous experiments, the electroreduction of the nitrate anion ( NO3) present in a concentration of 0.1 M in a 0.5 M sulfuric acid solution (pH = 1). The same figure shows the absence of loss of photoelectrochemical efficiency due to hollow / electron recombination processes.
    [0072] Through the different embodiments of the invention it is shown that the synthesized material is photoelectroactive towards various reactions in a wide pH range with high impact in the field of energy and the environment. In addition, it is shown that the core / shell structure of the synthesized nanoparticles has the property of minimizing photocurrent losses due to hollow / electron recombination processes when photoelectrorreduction processes of different chemical substances are carried out (hydrogen generation, reduction carbon dioxide and nitrate anion reduction) in the presence of simulated sunlight.
    权利要求:
    Claims (7)
    [1]
    1. Highly efficient nanomaterials characterized by presenting a shell core structure of between 10-60 nm in particle size that have photoelectrocatalytic properties when illuminated with light with a wide wavelength range from UV to visible.
    [2]
    2. Nanomaterials according to claim 1 comprising an electrically conductive and electroactive transition metal carbide core.
    [3]
    3. Nanomaterials according to claim 2 comprising a shell of amorphous phases of photoactive semiconductor oxides of the same transition metal as that comprised in the core.
    [4]
    4. Nanomaterials according to claim 3, wherein the core is molybdenum carbide and the shell is molybdenum oxide.
    [5]
    5. Use of the material according to claim 4 as a photoelectrocatalyst in molecular hydrogen generation reactions throughout the PH range.
    [6]
    6. Use of the material according to claim 4 as a photoelectrocatalyst in carbon dioxide reduction reactions.
    [7]
    7. Use of the material according to claim 4 as a photoelectrocatalyst in nitrate reduction reactions.
    类似技术:
    公开号 | 公开日 | 专利标题
    Liu et al.2018|Porous MoP network structure as co-catalyst for H2 evolution over g-C3N4 nanosheets
    Hao et al.2017|Peculiar synergetic effect of MoS2 quantum dots and graphene on Metal-Organic Frameworks for photocatalytic hydrogen evolution
    He et al.2019|A multifunctional platform by controlling of carbon nitride in the core-shell structure: from design to construction, and catalysis applications
    Huang et al.2017|Single-unit-cell layer established Bi2WO6 3D hierarchical architectures: efficient adsorption, photocatalysis and dye-sensitized photoelectrochemical performance
    Zhang et al.2018|Facile synthesis of multi-shelled ZnS-CdS cages with enhanced photoelectrochemical performance for solar energy conversion
    Cheng et al.2020|Facile preparation of nanosized MoP as cocatalyst coupled with g-C3N4 by surface bonding state for enhanced photocatalytic hydrogen production
    Jiang et al.2019|Hierarchical CsPbBr 3 nanocrystal-decorated ZnO nanowire/macroporous graphene hybrids for enhancing charge separation and photocatalytic CO 2 reduction
    Liu et al.2018|Efficient photocatalytic H2 production via rational design of synergistic spatially-separated dual cocatalysts modified Mn0. 5Cd0. 5S photocatalyst under visible light irradiation
    Liu et al.2017|Charge transmission channel construction between a MOF and rGO by means of Co–Mo–S modification
    Gong et al.2019|NiSe as an effective co-catalyst coupled with TiO2 for enhanced photocatalytic hydrogen evolution
    Zhang et al.2015|Photocatalytic water oxidation by layered Co/h-BCN hybrids
    Li et al.2017|Hydrogen generation by photocatalytic reforming of glucose with heterostructured CdS/MoS2 composites under visible light irradiation
    Huang et al.2019|Self-sacrifice transformation for fabrication of type-I and type-II heterojunctions in hierarchical BixOyIz/g-C3N4 for efficient visible-light photocatalysis
    Liu et al.2019|Facile synthesis of C-doped hollow spherical g-C3N4 from supramolecular self-assembly for enhanced photoredox water splitting
    Ampelli et al.2012|The use of a solar photoelectrochemical reactor for sustainable production of energy
    Wang et al.2017|New insights into high-valence state Mo in molybdenum carbide nanobelts for hydrogen evolution reaction
    Subha et al.2018|Direct Z-scheme heterojunction nanocomposite for the enhanced solar H2 production
    Sun et al.2021|Hydrogen spillover effect induced by ascorbic acid in CdS/NiO core-shell pn heterojunction for significantly enhanced photocatalytic H2 evolution
    Li et al.2019|Effect of visible light irradiation on hydrogen production by CoNi2S4/CdWO4 controllable flower spherical photocatalyst
    Jing et al.2019|Design and synthesis of Mo2C/MoO3 with enhanced visible-light photocatalytic performance for reduction of Cr | and degradation of organic pollutants
    Lian et al.2021|Engineering BiVO4@ Bi2S3 heterojunction by cosharing bismuth atoms toward boosted photocatalytic Cr | reduction
    Zhang et al.2013|Photocatalytic hydrogen evolution with simultaneous degradation of organics over | 0.2 Zn1. 6S2 solid solution
    Xue et al.2021|Accelerating directional charge separation via built-in interfacial electric fields originating from work-function differences
    Yang et al.2019|Synthesis, growth mechanism and photocatalytic H 2 evolution of CdS/CuS composite via hydrothermal method
    Idris et al.2022|Dye-Sensitized Fe-MOF nanosheets as Visible-Light driven photocatalyst for high efficient photocatalytic CO2 reduction
    同族专利:
    公开号 | 公开日
    ES2862426B2|2022-02-28|
    引用文献:
    公开号 | 申请日 | 公开日 | 申请人 | 专利标题
    CN105772048A|2016-03-26|2016-07-20|吉林大学|Molybdenum carbide and titanium dioxide compounded photocatalytic water-decomposing hydrogen production catalyst and preparation method of molybdenum carbide and titanium dioxide compounded photocatalytic water-decomposing hydrogen production catalyst|
    CN106475118A|2016-09-20|2017-03-08|天津城建大学|A kind of preparation method of the nuclear-shell structured nano-composite material for photoelectrocatalysiss|
    法律状态:
    2021-10-07| BA2A| Patent application published|Ref document number: 2862426 Country of ref document: ES Kind code of ref document: A1 Effective date: 20211007 |
    2022-02-28| FG2A| Definitive protection|Ref document number: 2862426 Country of ref document: ES Kind code of ref document: B2 Effective date: 20220228 |
    优先权:
    申请号 | 申请日 | 专利标题
    ES202000050A|ES2862426B2|2020-04-06|2020-04-06|HIGHLY EFFICIENT NANOMATERIALS|ES202000050A| ES2862426B2|2020-04-06|2020-04-06|HIGHLY EFFICIENT NANOMATERIALS|
    [返回顶部]