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KR-20260063629-A - PHOTOANODE, PREPARATION METHOD THEREOF AND WATER SPLITTING SYSTEM COMPRISING THE SAME

KR20260063629AKR 20260063629 AKR20260063629 AKR 20260063629AKR-20260063629-A

Abstract

A photoanode according to embodiments of the present invention can provide enhanced photoelectrochemical performance by comprising a transparent electrode substrate; and a hematite layer disposed on the transparent electrode substrate and having a porous structure comprising a plurality of hematite particles doped with aluminum (Al) and titanium (Ti). Furthermore, according to embodiments of the present invention, a water splitting device having enhanced photoconversion efficiency is provided by including the above-described photoanode.

Inventors

  • 장지현
  • 소우롭 샬레
  • 강지훈

Assignees

  • 울산과학기술원

Dates

Publication Date
20260507
Application Date
20241030

Claims (18)

  1. Transparent electrode substrate; and A photonode comprising a hematite layer having a porous structure and comprising a plurality of hematite particles doped with aluminum (Al) and titanium (Ti), disposed on the transparent electrode substrate.
  2. In paragraph 1, The above plurality of hematite particles are photonodes having a rod shape.
  3. In paragraph 1, A photonode in which the doping amount of aluminum (Al) relative to iron (Fe) on the surface of the hematite particles is 4.0 atomic% to 8.0 atomic%.
  4. In paragraph 1, A photonode in which the doping amount of aluminum (Al) relative to iron (Fe) in the above particle decreases as it moves from the surface of the particle toward the interior of the particle.
  5. In paragraph 1, A photonode having a doping amount of titanium (Ti) relative to iron (Fe) on the surface of the above particle of 3.0 atomic% to 6.0 atomic%.
  6. In paragraph 1, A photonode in which the doping amount of titanium (Ti) relative to iron (Fe) in the above particle decreases as it moves from the surface of the particle toward the interior of the particle.
  7. In paragraph 1, A photonode having a total pore volume of the hematite layer of 0.001 mg/ cm³ to 0.03 mg/ cm³ .
  8. In paragraph 1, A photonode having an average diameter of pores formed in the particles of the above, ranging from 10 nm to 30 nm.
  9. In paragraph 1, A photonode, wherein the hematite layer comprises a co-catalyst and further comprises a coating covering at least a portion of the surface of the particle.
  10. In Paragraph 9, The above co-catalyst is a photoanode comprising NiFeOx (x is 1 to 4).
  11. A step of coating a transparent electrode substrate with a mixed solution containing an iron (Fe) source and a titanium (Ti) source; A step of heat-treating the transparent electrode substrate to form a pre-layer containing titanium-doped iron hydroxide (Ti-FeOOH) on the transparent electrode substrate; A step of forming an aluminum coating layer by spin-coating an aluminum (Al) source onto the above-mentioned preparatory layer; and A method for manufacturing a photonode, comprising the step of heat-treating a pre-layer on which the aluminum coating layer is formed to form a hematite layer containing aluminum and titanium-doped hematite (Al:Ti- Fe₂O₃ ) particles.
  12. In Paragraph 11, A method for manufacturing a photonode, wherein the above-mentioned preparatory layer comprises a plurality of crystals having a rod shape and containing the titanium-doped iron hydroxide.
  13. In Paragraph 12, A method for manufacturing a photonode, wherein a plurality of crystals having the above rod shape have a non-porous structure and are converted into a porous structure in the step of heat-treating a pre-layer on which the aluminum coating layer is formed.
  14. In Paragraph 12, A method for manufacturing a photonode, wherein the aluminum coating layer covers at least a portion of the surface of the plurality of crystals.
  15. In Paragraph 11, A method for manufacturing a photoanode, wherein the thickness of the aluminum coating layer is 0.1 nm to 3.0 nm.
  16. In Paragraph 11, In the step of forming the hematite layer, A method for manufacturing a photonode, wherein aluminum contained in the aluminum coating layer diffuses from the aluminum source into the pre-layer and is doped into the titanium-doped iron hydroxide.
  17. In Paragraph 11, The above aluminum source includes an aqueous solution containing aluminum salt, and A method for preparing a photonode, wherein the concentration of the aluminum salt in the above aluminum salt-containing aqueous solution is 5 mg/ml to 30 mg/ml.
  18. A water splitting device comprising the photonode of claim 1.

Description

Photonode, preparation method thereof and water splitting system comprising the same The present invention relates to a photonode, a method for manufacturing the same, and a water splitting device including the same. As energy consumption increases, environmental issues are also becoming increasingly important. The development of clean, low-cost, and renewable energy sources is a critical task that satisfies both energy and environmental aspects, and recently, water splitting reactions using light energy have been proposed as a new method for hydrogen production as an eco-friendly approach. Water splitting is a reaction mechanism that generates hydrogen gas by solar energy in a photoelectrochemical (PEC) cell. The PEC cell includes a photoanode and a counter electrode, where an oxygen evolution reaction (OER) occurs at the photoanode and a hydrogen evolution reaction (HER) occurs at the counter electrode. As a photocatalyst, hematite is receiving much attention as a suitable material for PEC water splitting due to its theoretical solar-to-hydrogen conversion (STH) efficiency of about 15.3%, excellent stability in aqueous systems, and abundant resources. However, in practice, hematite has problems such as a short hole diffusion length of about 2 nm to 4 nm, low electrical conductivity, slow charge transfer to the interface, and high recombination characteristics. To solve these problems, methods such as heterojunction formation, doping of heteroatoms, and co-catalyst deposition have been studied. For example, lattice deformation (distortion) through high-pressure treatment can be introduced to improve the electron transport properties of hematite, but high-pressure treatment is not suitable for the operation of photocatalysts, and there may be limitations in improving PEC performance due to changes in the optoelectronic properties of the material caused by phase transitions. Therefore, there is a need for research on hematite and photonodes containing it that can be manufactured in a cost-effective manner while improving PEC performance by having a short hole diffusion path. Figure 1 is a schematic diagram illustrating the atomic arrangement of a hematite lattice according to doping elements. FIG. 2 is a schematic diagram illustrating a manufacturing process of a photonode according to one embodiment. Figure 3 is a graph showing the volume change of hematite according to doping elements. Figure 4 is a graph showing the formation energy of Al - Fe₂O₃ , Ti- Fe₂O₃ , and Al:Ti- Fe₂O₃ . Figure 5 is a graph showing the XRD patterns of Fe₂O₃ , Al- Fe₂O₃ , and Al :Ti- Fe₂O₃ . Figure 6 is a graph showing the Fourier transform of the Fe K-edge EXAFS spectra for Fe₂O₃ and Al:Ti- Fe₂O₃ . Figures 7a, b , and c are SEM images of Al- Fe₂O₃ , Al:Ti- Fe₂O₃ , and Ti- Fe₂O₃ , respectively. Figure 8 is a photographic image of Al:Ti- Fe₂O₃ and Ti - Fe₂O₃ . Figure 9 is an SEM image of a cross- section of Al:Ti- Fe₂O₃ and Ti - Fe₂O₃ . Figure 10 is a TEM image taken at each step of the Al:Ti- Fe₂O₃ manufacturing process of Example 1 . Figure 11 is a graph showing the UV -vis spectra of Ti- Fe₂O₃ , Al- Fe₂O₃ , and Al:Ti- Fe₂O₃ . Figure 12 is a tauc plot showing the energy band gaps of Ti- Fe₂O₃ , Al- Fe₂O₃ , and Al:Ti- Fe₂O₃ . Figure 13 is a graph showing the incident photon conversion efficiency ( IPCE ) of Ti- Fe₂O₃ , Al- Fe₂O₃ , and Al:Ti- Fe₂O₃ . Figure 14 is an elemental mapping image showing scanning transmission electron microscopy (STEM) and analysis results for Al:Ti- Fe₂O₃ . Figures 15 and 16 are graphs showing the XPS depth profile of Al:Ti- Fe₂O₃ , respectively. Figure 17 is a graph obtained by performing 3D TOF-SIMS (Time-of-Flight Secondary Ion Mass Spectrometry) analysis on Al:Ti- Fe₂O₃ . Figure 18 is a graph showing the XPS spectrum of Al:Ti- Fe₂O₃ . Figure 19 is a graph showing the electrochemical properties of Fe₂O₃ , Ti- Fe₂O₃ , Al- Fe₂O₃ , and Al :Ti- Fe₂O₃ . Figures 20a and 20b are the LSV curve with hole scavengers and the LSV curve without hole scavengers, respectively. Figures 21a and 21b are graphs showing the open circuit potential (OCP) of the Ti- Fe₂O₃ photoenonode, Al- Fe₂O₃ photoenonode , and Al:Ti- Fe₂O₃ photoenonode . Figure 22a is a graph showing the photoluminescence (PL) spectra of Ti- Fe₂O₃ photoenonodes , Al- Fe₂O₃ photoenonodes , and Al:Ti- Fe₂O₃ photoenonodes, and Figure 22b is a graph showing the time-resolved PL spectra in the steady state. Figure 23 is a graph showing the Gibbs free energy at each OER stage for Al :Ti- Fe₂O₃ according to externally applied potential. FIG . 24a is a graph showing the LSV curve of Al:Ti- Fe₂O₃ according to the concentration of the AlCl₃ solution in Example 1. FIG . 24b is a graph showing the photocurrent density at 1.23 V RHE of each prepared Al:Ti- Fe₂O₃ . Fig. 25a is Al:Ti- Fe₂O₃ and Figure 25 shows a linear scanning potential (JV) curve in a three-electrode cell of NiFeO x /Al:Ti- Fe₂O₃ , Figure 25 b shows a graph of the amount of gas emitted and the Farada