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Enhanced Patterned Cocatalyst TiO2/Fe2O3 Photoanodes for Water-Splitting

Abstract

In this study, we used a hot-pressing process to enhance the photocatalytic properties of TiO2/Fe2O3 bimetallic oxide with a periodic patterned structure on the surface to increase photon absorption for photocatalysis in the oxygen evolution reaction for water splitting. The hot-pressed samples show that combining the two metal oxides improves the absorption band edge of the electrode at different wavelengths. The patterned structure obtained using the hot-pressing process successfully improves photon absorption, resulting in a two-fold enhancement compared with a flat surface electrode.

Introduction

Photocatalytic decomposition for water splitting to produce oxygen is a widely studied light energy conversion system [1,2,3,4]. When photons of different wavelengths are irradiated onto a semiconductor photocatalyst, their energy agitates its valence band electrons, making them jump to the conduction band. A photo-generated hole is formed in the valence band, and the excited electrons in the conduction band undergo a reduction reaction with water molecules to produce hydrogen via the so-called hydrogen evolution reaction (HER) [5]. This hole dominates oxygen production via the so-called oxygen evolution reaction (OER) [6]. The edge of the conduction band of the semiconductor photocatalyst material must be above the H+/H2 reduction energy level. The photoelectrons in the photocatalyst can reduce water to hydrogen. However, because the oxidation–reduction potential difference of the water-splitting reaction is 1.23 eV, the valence band energy level of the photocatalyst must be below the oxidation energy level of O2/H2O to oxidize water to oxygen.

To achieve this goal, the adjustment of the required energy and the coordination of the solar radiation spectrum is important [1]. Most previous studies have used noble metals such as Pt and Au as catalysts [2, 5,6,7]; however, these are expensive and scarce, and therefore, studies have been conducted to find alternative catalytic materials. In this regard, typical semiconductor metal oxides have attracted much attention. Abundant metal oxides such as titanium dioxide (TiO2) [8, 9], WO3 [10, 11], BiVO4 [12, 13], CuO2 [14, 15], and ferric oxide (Fe2O3) [16, 17] enhance photon absorption through their n- or p-type semiconductor properties and energy gap matching; therefore, they show high photocatalytic efficiency over a large wavelength range. The photon energy of a specific wavelength can cause the separation of electron–hole pairs, further promoting the conversion of light energy into chemical energy. TiO2 [18,19,20,21] and Fe2O3 [22, 23] are commonly used for photocatalysis because they afford advantages such as simple preparation, high chemical stability, low cost, nontoxicity, and corrosion resistance; further, the energy gap of TiO2 (3.2 eV) shows good agreement with to the energy gap (2.2 eV) of Fe2O3 [24, 25], as shown in Fig. 1a. This property allows the bimetallic semiconductor formed by combining these two metal oxides to absorb more than 30% of the band gap effectively. Sunlight [26] can effectively enhance the photocatalytic effect of the electrode.

Fig. 1
figure1

a Water-splitting reaction mechanism in TiO2/Fe2O3 bimetallic semiconductor system. b Fabrication of pattern using hot-pressing process

The dimensional structure of the electrode surface also influences the photoelectrochemical properties. In particular, periodic microstructures have attracted much interest in the field of optics. Yablonovitch and John described this concept in 1987 [27]. They aimed to design a medium that can capture photons to reduce energy consumption and waste. Through several years of research, they found that a medium with a particular periodic structure on the surface effectively traps photons [28, 29] without changing the intrinsic chemical properties of matter to obtain the required optical properties. Thus far, many studies on solar energy have selected materials with periodic structures to increase photon energy absorption [30]. Further, because a periodic microstructure drastically increases the reaction area of the electrode surface, the current response obtained will also be significantly improved.

In this study, we fabricated a simple pattern using a hot-pressing process onto the photoanode surface, as shown in Fig. 1b, and used an etching method to form an original substrate with a periodic surface structure. The original substrate is remolded by a polymer to serve as a new stamp substrate that is then used as a mold with the prepared layer of the TiO2/Fe2O3 cocatalyst. Finally, a hot-pressing process is performed to obtain a periodic microstructure. This process improves the carrier transfer rate through improved interface contact within the cocatalyst material and improves light absorption efficiency through additional light trapping and scattering from the surface patterns.

Methods

Preparation of the Fe2O3 and TiO2 Powder

FeCl2 and FeCl3 were dissolved in deionized water, stirred to form a solution, quickly poured into a sodium hydroxide solution, and finally stirred at 80 °C for 30 min. After the solution was thoroughly mixed, it was left to stand for 30 min until the product precipitated. The upper layer solution was removed; the precipitate was washed with acetone, ethanol, and deionized water; and it was dried at 120 °C for 12 h to obtain Fe3O4 (black powder). This powder was dissolved in alcohol and stirred vigorously for 30 min to obtain a reddish-brown Fe2O3 suspension solution. Finally, the precipitated Fe2O3 was placed in a quartz boat that in turn was placed in a sintering furnace at 450 °C for 3 h and then cooled to room temperature naturally to obtain Fe2O3 powder with a hematite phase. A TiO2 precursor solution was obtained by the addition of tetraethyl titanic acid to n-propanol to prepare a precursor solution followed by the addition of sulfuric acid and stirring at room temperature, allowing it stand to at 25 °C for 2 h to form a translucent gel, placing in an oven at 50 °C, reheating it, and naturally cooling it to room temperature.

Preparation of the Bimetallic Oxide Colloidal Solution

Finally, we prepared 7 wt% polyvinyl alcohol (PVA), added 1 mL of deionized water, and placed it on a hot plate at 120 °C for 30 min. Then, we stirred the PVA to make it effectively dissolve in deionized water to obtain solution A. We prepared 20 mg of Fe2O3 powder and 98 µL of TiO2 solution to dissolve in 1 mL of N-methyl-2-pyrrolidone (NMP), placed it in an ultrasonic oscillator, shook it for 30 min to obtain fixed solutions, and placed them in an ultrasonic oscillator for 30 min to obtain the final semiconductor bimetallic oxide colloidal solution.

Preparation of the Periodic Structure on the Electrodes

We used the imprint lithography process to fabricate the silicon wafer for the soft stamp [31,32,33]. Furthermore, to prepare the soft stamp, we first used acetone, ethanol, and water to vibrate the silicon wafer after the 20-min etching process to clean the board and then placed it on a heating plate at 40 °C for drying. Simultaneously, the epoxy resin was activated and then laid flat on the original substrate surface until it dried. After drying, the epoxy resin was torn off from the original substrate to obtain the required soft stamp. We applied 100 µL of the semiconductor bimetallic oxide colloidal solution to the TiO2 film surface and kept it at room temperature for 1 h until the colloidal solution changed to a jelly-like state, and then, we performed the hot-pressing process for 15 min. Finally, the patterned photoanode was placed in a sintering furnace at 500 °C for 3 h in an argon atmosphere to obtain the patterned photoanode with a periodic structure. The OER performance of the photoanode was examined using the three-electrode connection method. The system included the working electrodes, a counter electrode (carbon rod), and a reference electrode (Ag/AgCl) in 1 M KOH as the electrolyte.

Results and Discussion

The surface-patterned structure was verified as shown in Fig. 2. Figure 2a shows a scanning electron microscope (SEM) image of the silicon wafer as a mother mold substrate. The surface had periodically arranged circular holes, each having an elongated 2-µm aperture. Figure 2b shows an image of the corresponding inverse pattern on the epoxy resin surface. The epoxy resin successfully replicated the whole structure from the original pattern of the Si substrate, which correspondingly showed periodically arranged cylindrical structures with a diameter of 2 µm. Finally, we examined whether the corresponding patterned periodic structure is transferred to the electrode surface via the hot-pressing process. Figure 2c shows the patterned TiO2/Fe2O3 photoanode before and after visible light irradiation. This figure shows that the electrode surface looks black when it is not illuminated. However, it shows a noticeable rainbow color under visible light irradiation, implying that the incident light is significantly trapped and refracted many times in the periodic patterned structure. Figure 2d, e presents SEM images of the surface of a patterned TiO2/Fe2O3 photoanode under different magnifications and angles. The photoelectrode surface exhibited a cycle similar to that of a silicon wafer motherboard. The pore size was approximately 2 µm, confirming that we successfully imprinted periodically patterned microstructures on the electrode surface. Finally, Fig. 2f presents a cross-sectional image produced by cutting the electrode surface using a focused ion beam (FIB). The cross-sectional image also shows the circular hole shape of this periodic patterned structure, with the hole depth being 0.642 µm. We also successfully used the anodic aluminum oxide as a stamp to fabricate a smaller pattern, and the SEM images can be found in Additional file 1: Fig. S1.

Fig. 2
figure2

a SEM image of silicon wafer prepared using etching method. b Soft stamp made using silicon wafer with inverse pillar structure. c Photos captured with and without light irradiation. de SEM image under different magnifications and angles. f Cross-sectional image of electrode surface of TiO2/Fe2O3 ordered patterned photoanode

To characterize the proposed TiO2/Fe2O3 patterned photoanode, we conducted FIB-transmission electron microscope (TEM) analysis. Figure 3a presents the result of the element distribution analysis (EDS mapping) of the TiO2/Fe2O3 patterned photoanode. Fe, Ti, and O were uniformly distributed in the electrode, and the C signal arose from the PVA and NMP binders; however, this did not affect the distribution of the primary materials, namely TiO2 and Fe2O3. Figure 3b presents STEM images obtained under different magnifications. TiO2 and Fe2O3 powders exhibited granular morphologies. As shown in Fig. 3c, the lattice parameters of Fe2O3 and TiO2 were determined through the analysis to be 0.28 and 0.31 nm, respectively, indicating that the hot-pressing process created lattice distortion in both Fe2O3 and TiO2.

Fig. 3
figure3

FIB-TEM image of TiO2/Fe2O3-ordered patterned photoanode with a EDS mapping of C, O, Ti, and Fe. b STEM images with different magnifications. c Analysis of Fe2O3 and TiO2 lattices

Furthermore, we performed X-ray photoelectron spectroscopy (XPS) to determine the chemical states of elements. Figure 4 presents the results of the fine scan spectrum analysis performed using XPS for the six elements in the photoanode, and the full XPS survey spectrum can also obtain in Additional file 1: Fig. S2. In Fig. 4a, the C 1s orbital shows signals corresponding to a C–C single bond and a C–O single bond at a binding energy of 284.9 eV. In Fig. 4b, the O 1s orbital shows a signal of the C=O double bond at a binding energy of 532.5 eV, confirming that many oxidized carbons exist on the electrode surface and a signal of the O from the oxides at a binding energy of 530 eV. In Fig. 4c, the N 1s orbital shows signals of the N–H bond at binding energies of 397.2 and 400 eV. The bonding N and metal ion may result from the bond between N and a small amount of transition metal elements is also seen. In Fig. 4d, Fe 2p2/3 and Fe 2p1/3 signals are seen at binding energies of 711.3 and 724.8 eV, respectively, and satellite peaks of Fe 2p2/3 and Fe 2p1/3 are seen at binding energies of 720 and 731.3 eV, respectively; these are typical Fe2O3 configuration signals. In Fig. 4e, Ti 2p3/2 and Ti 2p1/2 signals are seen at binding energies of 457.9 and 464.3 eV, respectively; these are generated by TiO2. In Fig. 4f, Sn 3d3/2 and Sn 3d5/2 signals are seen at binding energies of 285.9 and 495.1 eV, respectively; these are generated by the SnO2 substrate.

Fig. 4
figure4

XPS spectra of TiO2/Fe2O3-ordered patterned photoanode for a C 1s, b O 1s, c N 1s, d Fe 2p, e Ti 2p, and f Sn 3d

To demonstrate the effect of patterned structures on the light absorption of the photoanode, we performed ultraviolet–visible spectroscopy (UV–Vis) before and after the hot-pressing process, as shown in Fig. 5a. Owing to the cocatalyst effect of the TiO2 and Fe2O3 metal oxides, the photoanode demonstrated light absorption over a broad range of 400–600 nm. Compared with the electrode before the patterning process, the photoanode exhibited additional light absorption owing to enhanced light scattering and absorption from the periodic patterned structure on the surface. This enhancement is also reflected in the linear scanning voltammetry (LSV) shown in Fig. 5b; the TiO2/Fe2O3 sample produced using the hot-pressing process exhibited the highest reaction current during the LSV scan. Furthermore, the EIS measurement and the Tafel slope can found in the Additional file 1: Figs. S3 and S5. Besides, we performed a photoresponse study under zero bias and white light irradiation, and this sample showed two-fold improvement compared with the TiO2/Fe2O3 sample produced without using the hot-pressing process and seven-fold current improvement compared with TiO2 only, as shown in Fig. 5c. We also selected the green laser with a wavelength of 532 nm and red laser with 633 nm for measurement, and the result can be found in Additional file 1: Fig. S4.

Fig. 5
figure5

a UV–Vis absorption spectra. b LSV swipe scan. c Photoresponses of different photoanodes

Conclusion

In this study, we demonstrated a simple hot-pressing process to fabricate a periodic pattern on a TiO2/Fe2O3 cocatalyst bimetallic oxide photoanode. A clear periodic pattern of holes was reproduced on the photoanode surface. A broadband UV–Vis absorption spectrum of the TiO2/Fe2O3 bimetallic oxide was obtained, and it showed light absorption over a broad range of 400–600 nm. Finally, the TiO2/Fe2O3 cocatalyst with a patterned surface exhibited a significantly enhanced photocurrent owing to the additional light absorption and scattering from the surface structure.

Availability of data and materials

All data generated or analyzed during this study are included in this published article [and its supporting information files].

Abbreviations

OER:

Oxygen evolution reaction

HER:

Hydrogen evolution reaction

PVA:

Polyvinyl alcohol

NMP:

N-methyl-2-pyrrolidone

SEM:

Scanning electron microscope

FIB:

Focused ion beam

TEM:

Transmission electron microscope

EDS:

Energy dispersive spectroscopy

STEM:

Scanning transmission electron microscopy

XPS:

X-ray photoelectron spectroscopy

UV–Vis:

Ultraviolet-visible spectroscopy

LSV:

Linear scanning voltammetry

References

  1. 1.

    Takata T et al (2020) Photocatalytic water splitting with a quantum efficiency of almost unity. Nature 581(7809):411–414

    CAS  Article  Google Scholar 

  2. 2.

    Maeda K, Domen K (2010) Photocatalytic water splitting: recent progress and future challenges. J Phys Chem Lett 1(18):2655–2661

    CAS  Article  Google Scholar 

  3. 3.

    Quan Q, Lai Z, Bao Y, Bu X, Meng Y, Wang W, Ho JC (2021) Self-anti-stacking 2D metal phosphide loop-sheet heterostructures by edge-topological regulation for highly efficient water oxidation. Small 66:2006860

    Article  Google Scholar 

  4. 4.

    Gao W, Gou W, Wei R, Bu X, Ma Y, Ho JC (2020) In situ electrochemical conversion of cobalt oxide@MOF-74 core-shell structure as an efficient and robust electrocatalyst for water oxidation. Appl Mater Today 21:100820

    Article  Google Scholar 

  5. 5.

    Mohammed-Ibrahim J, Sun X (2019) Recent progress on earth abundant electrocatalysts for hydrogen evolution reaction (HER) in alkaline medium to achieve efficient water splitting—a review. J Energy Chem 34:111–160

    Article  Google Scholar 

  6. 6.

    Tran DT et al (2019) Pt nanodots monolayer modified mesoporous Cu@CuxO nanowires for improved overall water splitting reactivity. Nano Energy 59:216–228

    CAS  Article  Google Scholar 

  7. 7.

    Wild J, McCready L (1950) Observations of the spectrum of high-intensity solar radiation at metre wavelengths. I. The apparatus and spectral types of solar burst observed. Aust J Chem 3(3):387–398

    Article  Google Scholar 

  8. 8.

    Yu J, Qi L, Jaroniec M (2010) Hydrogen production by photocatalytic water splitting over Pt/TiO2 nanosheets with exposed (001) facets. J Phys Chem C 114(30):13118–13125

    CAS  Article  Google Scholar 

  9. 9.

    Galińska A, Walendziewski J (2005) Photocatalytic water splitting over Pt-TiO2 in the presence of sacrificial reagents. Energy Fuels 19(3):1143–1147

    Article  Google Scholar 

  10. 10.

    Iwase A, Kato H, Kudo A (2006) Nanosized Au particles as an efficient cocatalyst for photocatalytic overall water splitting. Catal Lett 108(1–2):7–10

    CAS  Article  Google Scholar 

  11. 11.

    Chiarello GL, Selli E, Forni L (2008) Photocatalytic hydrogen production over flame spray pyrolysis-synthesized TiO2 and Au/TiO2. Appl Catal B 84(1–2):332–339

    CAS  Article  Google Scholar 

  12. 12.

    Kumar SG, Rao KK (2017) Comparison of modification strategies towards enhanced charge carrier separation and photocatalytic degradation activity of metal oxide semiconductors (TiO2, WO3 and ZnO). Appl Surf Sci 391:124–148

    CAS  Article  Google Scholar 

  13. 13.

    Habisreutinger SN, Schmidt-Mende L, Stolarczyk JK (2013) Photocatalytic reduction of CO2 on TiO2 and other semiconductors. Angew Chem Int Ed 52(29):7372–7408

    CAS  Article  Google Scholar 

  14. 14.

    Huang T et al (2007) Photocatalytic activities of hetero-junction semiconductors WO3/SrNb2O6. Mater Sci Eng, B 141(1–2):49–54

    CAS  Article  Google Scholar 

  15. 15.

    Ma J et al (2018) Pt nanoparticles sensitized ordered mesoporous WO3 semiconductor: gas sensing performance and mechanism study. Adv Func Mater 28(6):1705268

    Article  Google Scholar 

  16. 16.

    Wang Q et al (2017) Designing non-noble/semiconductor Bi/BiVO4 photoelectrode for the enhanced photoelectrochemical performance. Chem Eng J 326:411–418

    CAS  Article  Google Scholar 

  17. 17.

    Tayebi M, Lee B-K (2019) Recent advances in BiVO4 semiconductor materials for hydrogen production using photoelectrochemical water splitting. Renew Sustain Energy Rev 111:332–343

    CAS  Article  Google Scholar 

  18. 18.

    Zhong Y, Fan JQ, Wang RF, Wang S, Zhang X, Zhu Y, Xue QK (2000) Direct visualization of ambipolar Mott transition in cuprate CuO2 planes. Phys Rev Lett 125(7):077002

  19. 19.

    Takagi H, Uchida S, Tokura Y (1989) Superconductivity produced by electron doping in CuO2-layered compounds. Phys Rev Lett 62(10):1197

  20. 20.

    Cherepy NJ et al (1998) Ultrafast studies of photoexcited electron dynamics in γ-and α-Fe2O3 semiconductor nanoparticles. J Phys Chem B 102(5):770–776

    CAS  Article  Google Scholar 

  21. 21.

    Xu Z, Yin M, Sun J, Ding G, Lu L, Chang P, Li D (2016) 3D periodic multiscale TiO2 architecture: a platform decorated with graphene quantum dots for enhanced photoelectrochemical water splitting. Nanotechnology 27(11):115401

    Article  Google Scholar 

  22. 22.

    Touba S, Kimiagar S (2019) Enhancement of sensitivity and selectivity of α-Fe2O3 nanorod gas sensors by ZnO nanoparticles decoration. Mater Sci Semicond Process 102:104603

    CAS  Article  Google Scholar 

  23. 23.

    Ahmed AM et al (2020) Enhanced photoelectrochemical water splitting activity of carbon nanotubes@TiO2 nanoribbons in different electrolytes. Chemosphere 238:124554

    CAS  Article  Google Scholar 

  24. 24.

    Wang G et al (2011) Hydrogen-treated TiO2 nanowire arrays for photoelectrochemical water splitting. Nano Lett 11(7):3026–3033

    CAS  Article  Google Scholar 

  25. 25.

    Sivula K, Le Formal F, Grätzel M (2011) Solar water splitting: progress using hematite (α-Fe2O3) photoelectrodes. Chemsuschem 4(4):432–449

    CAS  Article  Google Scholar 

  26. 26.

    Masoumi Z, Tayebi M, Lee B-K (2020) The role of doping molybdenum (Mo) and back-front side illumination in enhancing the charge separation of α-Fe2O3 nanorod photoanode for solar water splitting. Sol Energy 205:126–134

    CAS  Article  Google Scholar 

  27. 27.

    Fu Y et al (2020) A ternary nanostructured α-Fe2O3/Au/TiO2 photoanode with reconstructed interfaces for efficient photoelectrocatalytic water splitting. Appl Catal B 260:118206

    CAS  Article  Google Scholar 

  28. 28.

    Bashiri R et al (2020) Hierarchically SrTiO3@TiO2@Fe2O3 nanorod heterostructures for enhanced photoelectrochemical water splitting. Int J Hydrog Energy

  29. 29.

    Li Y et al (2016) Hierarchically branched Fe2O3@TiO2 nanorod arrays for photoelectrochemical water splitting: facile synthesis and enhanced photoelectrochemical performance. Nanoscale 8(21):11284–11290

    CAS  Article  Google Scholar 

  30. 30.

    Yablonovitch E (2001) Photonic crystals: semiconductors of light. Sci Am 285(6):46–55

    CAS  Article  Google Scholar 

  31. 31.

    Xia Y, Whitesides GM (1998) Soft lithography. Annu Rev Mater Sci 28(1):153–184

    CAS  Article  Google Scholar 

  32. 32.

    Plachetka U, Bender M, Fuchs A, Vratzov B, Glinsner T, Lindner F, Kurz H (2004) Wafer scale patterning by soft UV-nanoimprint lithography. Microelectron Eng 73:167–171

    Article  Google Scholar 

  33. 33.

    Van Truskett N, Watts MPC (2006) Trends in imprint lithography for biological applications. Trends Biotechnol 24(7):312–317

    CAS  Article  Google Scholar 

Download references

Funding

This work was financially supported by the “High Entropy Materials Center” from The Featured Areas Research Center Program within the Higher Education Sprout Project framework of the Ministry of Education (MOE). We acknowledge the support from Project MOST 106-2221-E-008-106-MY3, 109-2634-F-007-024-, 108-2218-E-007-045-, 108-3116-F-008-008- (Dr. Wei-Hsuan Hung), 107-2218-E-131-004-MY3 and 109-2221-E-131-016-MY3 (Dr. Chuan-Ming Tseng) and the support from Precious Instrument Utilization Center at National Central University.

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Contributions

Conceptualization was contributed by W-H H; methodology was contributed by W-H H, C-M T; formal analysis was contributed by W-H H, Y-J T, C-M T, and TTHN; investigation was contributed by Y-J T and TTHN; writing original draft was contributed by W-H H and Y-J T; writing, review and editing were contributed by W-H H, Y-J T, C-M T, and HTTN; supervision was contributed by W-H H and C-M T. The manuscript was written through the contributions of all authors. All authors have approved the final version of the manuscript.

Corresponding authors

Correspondence to Wei-Hsuan Hung or Chuan-Ming Tseng.

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Supplementary Information

Additional file 1.

Figure S1. SEM image and cross-sectional image of anodized aluminum template at different voltages (a) 30 V, (b) 60 V, (c) 90 V, (d) 120 V. And the corresponding transfer SEM images on the surface of epoxy resin, (a2) 30 V, (b2) 60 V, (c2) 90 V, (d2) 120 V. Figure S2. The full XPS survey spectrum analysis chart of patterned TiO2/Fe2O3 photoanode. Figure S3. The EIS measurement compares the difference between TiO2/Fe2O3 photoanode before and after hot pressing process. Figure S4. Compare the photocurrent response of patterned TiO2/Fe2O3 photoanode under two different laser irradiations. Figure S5. Tafel slope of the TiO2/Fe2O3 photoanodes with/without pattern.

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Hung, WH., Teng, YJ., Tseng, CM. et al. Enhanced Patterned Cocatalyst TiO2/Fe2O3 Photoanodes for Water-Splitting. Nanoscale Res Lett 16, 76 (2021). https://doi.org/10.1186/s11671-021-03529-8

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Keywords

  • Bimetallic oxide
  • Periodic pattern
  • Hot-pressing process
  • Water splitting