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Effects of platinum photodeposition time on the photoelectrochemical properties of Fe2O3 nanotube electrodes
Materials Letters 237 (2019) 188–192
Contents lists available at ScienceDirect
Materials Letters journal homepage: www.elsevier.com/locate/mlblue
Effects of platinum photodeposition time on the photoelectrochemical properties of Fe2O3 nanotube electrodes Mohamad Mohsen Momeni a,⇑, Yousef Ghayeb a, Akbar Hallaj a, Robabeh Bagheri b, Zhenlun Songd b, Hossein Farrokhpour a a
Department of Chemistry, Isfahan University of Technology, Isfahan 84156-83111, Iran Key Laboratory of Marine Materials and Related Technologies, Zhejiang Key Laboratory of Marine Materials and Protective Technologies, Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences, Ningbo 315201, PR China b
a r t i c l e
i n f o
Article history: Received 25 July 2018 Received in revised form 27 October 2018 Accepted 14 November 2018 Available online 15 November 2018 Keywords: Fe2O3 nanotube Platinum Deposition Photoelectrochemical Thin films
a b s t r a c t A photo-assisted deposition method for the deposition of platinum nanoparticles on Fe2O3 nanotubes (Pt/Fe2O3), prepared by anodizing, has been developed. The chemicophysical properties and elemental composition of the synthetic Pt/Fe2O3 samples have also been determined. The investigation of the photoelectrochemical properties of the prepared Pt/Fe2O3 samples showed their greatly increased photocurrent density for photoelectrochemical (PEC) water splitting compared to bare Fe2O3. Therefore, the deposition of Pt is effective on the enhancement of the PEC response. In addition, the effect of the Pt photodeposition time on water splitting capability was studied. The current density produced by sample HPt3 was 220 lA/cm2 at +0.4 V vs. Ag/AgCl, which is 2 times higher than that of the bare Fe2O3 nanotube samples (105 lA/cm2, at +0.4 V vs. Ag/AgCl). Ó 2018 Elsevier B.V. All rights reserved.
1. Introduction Given the relatively narrow band gap (2.0–2.2 eV), low cost, non-toxicity and high chemical stability (photo corrosion) of hematite (a-Fe2O3) in many solvents over a wide pH range and its stability in most electrolytes, it has been of great interest [1–4]. The unique properties of hematite make it a promising candidate as a photoelectrode in photoelectrochemical (PEC) cells. Nevertheless, the strong drawbacks of hematite such as low absorption coefficient, slow charge carrier mobility on the surface, poor electrical conductivity and high photo generated electron hole pair recombination rates, decrease its PEC water splitting efficiency [2–7]. Such disadvantages have to be overcome to improve the solar-to-hydrogen conversion efficiency of hematite. Two different approaches for this purpose include the preparation of nanostructures to increase the contact surface area with electrolytes [8] and prolonging charge lifetime by modification using various metals or catalysts [9]. The electrical conductivity, carrier concentration and optical absorption coefficient of hematite are enhanced by modification of its surface with metals. Many species have been introduced into Fe2O3 [1–7,9–12]. Platinum has attracted the most attention as one of the most effective elements ⇑ Corresponding author. E-mail address: [email protected] (M. Mohsen Momeni). https://doi.org/10.1016/j.matlet.2018.11.089 0167-577X/Ó 2018 Elsevier B.V. All rights reserved.
in this regard due to its noble metal property for catalysis [2,13– 15]. Hu et al. reported the preparation of Pt-doped a-Fe2O3 films by electrodeposition method [2]. Pt layer coated on a-Fe2O3 films were prepared by Zhang et al. through DC facing targets sputtering method and the photocatalytic activity of the film was investigated [13]. Although there are different publications on the preparation methods for Pt/hematite, to the best of the authors’ knowledge, Pt/Fe2O3 nanotube films fabricated by anodizing of iron plate and photochemical deposition of platinum have not yet been reported. A facile photoassisted deposition technique has been used for coating platinum on Fe2O3 nanotubes in this work. SEM, XRD, XPS, EDX and UV–visible have been used for characterization of the samples obtained. The effect of deposited platinum on the photocatalytic activities was explored by carrying out photoelectrochemical measurements. The details on the preparation, characterization and photoelectrochemical testing of Pt/Fe2O3 samples can be found in the Supporting Information. 2. Results and discussion Fig. 1(a) shows the SEM image of the Fe2O3 nanotube films prepared by anodization of iron foil prior to platinum photodeposition. The average inner diameter of the pore is approximately 43 nm and the wall thickness and the length of the tube are about 20 nm and 4 lm, respectively. As observed, the nanotubes are
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Fig. 1. FESEM images of prepared samples in 1 lm scale with 30 KX magnifications; (a) sample H, (b) sample HPt1, (c) sample HPt2, (d) sample HPt3, (e) sample HPt4 and (f) sample HPt5.
arranged orderly and closely with almost uniform diameters and wall thicknesses. Fig. 1b-f show the surface morphologies of the Pt/Fe2O3 samples with the deposition times of 20, 40, 60, 120 and 300 s, respectively. As the increment in the wall thickness shows, platinum nanoparticles have been deposited around the Fe2O3 nanotube wall. After photo deposition of platinum, the tube diameter of HPt1 to HPt5 is 41.98, 39.83, 38.47, 37.45 and 34.90 nm, respectively. A junction layer of the sediment particles have covered the Fe2O3 tube arrays following the photodeposition and the structures obatined are more like porous films. The morphology of the films vary depending on the change of the deposition time. Deposited particles cover the tubes on further increase of the deposition time. Fig. 2a shows the X-ray diffraction (XRD) patterns of the bare Fe2O3 and Pt/Fe2O3 samples. The characteristic peaks at (1 1 1), (2 0 0), (2 2 0) and (3 1 1), associated with platinum, are observed in addition to the intensive Fe2O3 signals at planes (0 2 1), (1 0 4), (1 1 0), (1 1 6), (0 2 4), (1 1 6), (2 1 4), (3 0 0) and (1 1 9), which verify Pt/Fe2O3 formation. The sharp peaks in the recorded XRDs confirms the crystalline structure for the synthesized structures. The XPS surface analysis was carried out to further study the surface
chemical compositions of the Pt/Fe2O3 samples. The survey scan of XPS spectra, indicating the presence of C, Fe, Pt and O, is shown in Fig. 2b. As Fig. 2c shows, the residual carbon is due to the adventitious carbon arising from exposure to air [1]. Two characteristic 2p 3/2 and 2p 1/2 bands of Fe3+ at 712 and 726 eV, respectively, are identified in the high resolution Fe 2p spectrum (Fig. 2d). In addition, a typical Fe3+ satellite peak, typical of a-Fe2O3, is also observed at a binding energy of 718.98 eV. Two peaks are observed at 80 eV (4f 5/2) and 74 eV (4f 7/2) in the Pt 4f spectrum (Fig. 2f), which could be ascribed to PtO2 [16]. The presence of Fe, Pt, C and O, as the only elements in this sample, is shown in EDX spectrum of Pt/Fe2O3 sample (Fig. S2). EDX mapping was used to study the elemental distribution in the Pt/Fe2O3 sample and the corresponding results are shown in the Electronic Supplementary Information. The presence of iron and Pt on the nanotube are confirmed by the EDX mapping shown in Fig. S3. Fig. 3a shows the UV–Vis absorption spectra of bare Fe2O3 and Pt/Fe2O3. Similar absorption features are exhibited by all the films. A peak in the range of 360–480 nm is usually observed, which is characteristic of Fe2O3 films and originates from the indirect Fe 3d to 3d and direct O 2p to Fe 3d transitions [17]. As shown in
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Fig. 2. (a) Typical XRD patterns of the prepared samples; XPS spectra of the Pt/Fe2O3: (b) survey, (c) C 1s, (d) Fe 2p, (e) O 1s and (f) Pt 4f.
figure, the maximum absorption spectrum shifts from 360 nm in bare Fe2O3 to 480 nm in HPt1 sample, but it should be noted that there is no regular trend in absorbance spectral shift of Fe2O3 with various Pt loading. Therefore, a major portion of the light in the visible region can be absorbed by Pt/Fe2O3 samples to produce electron hole pairs, which may in turn give rise to the high photocatalytic activity of these novel samples. Voltammogram experiments have been used to evaluate the photoelectrochemical properties of the samples prepared. The voltograms of photocurrent vs. the applied voltage of different electrodes as a function of the photodeposition time are shown in Fig. 3b. Under illumination, the photocurrent observed is known to be directly related to the water splitting rate, which shows the number of charge carriers produced from the incident light and
their subsequent participation in water oxidation on the photoanode and hydrogen ion reduction on the counter electrode [2]. Under light, a photocurrent of 220 lA/cm2 was observed at +0.4 V potential for HPt3 sample, which is much higher than that of the bare Fe2O3 nanotube sample (105 lA/cm2). The plot of photocurrent density vs. time for various samples at 0.4 V constant potential vs. Ag/AgCl reference electrode under illumination with 50 s light on/off cycle for 300 sec in 0.1 M Na2S and 0.1 M Na2SO3 solutions (pH = 9) is shown in Fig. 3c. Upon illumination, the photocurrent increases at once and remains constant throughout the illumination, but suddenly drops when the light is turned off. The photocurrent response is observed to change with the photodeposition time. Generally speaking, the photocurrents of the samples containing Pt are much higher than those of the samples
M. Mohsen Momeni et al. / Materials Letters 237 (2019) 188–192
191
without Pt (except for sample HPt2). This indicates the participation of a much larger number of photoelectrons in the water splitting reaction. In general, slow surface kinetics has been suggested to induce charge recombination at the Fe2O3 surface [18]. Thus, a possible explanation for the increased photocurrent of Ptdeposited samples is that a catalytic function for water splitting reaction is provided by Pt on the surface of the Fe2O3. Furthermore, platinum deposition may enhance the electric field, leading to higher charge separation efficiency and a large photocurrent density. It must be pointed out that an optimal platinum photodeposition time is required for good photoresponse. 3. Conclusions Porous Pt/Fe2O3 films have been prepared by electrochemical anodizing and photochemical deposition. Highly ordered Fe2O3 nanotubes have been successfully fabricated on pure iron foils via electrochemical anodizing, followed by the deposition of platinum (Pt/Fe2O3) through photodeposition. XRD, FE-SEM, EDS, XPS and UV–Vis absorption spectra were used to systematically characterize all the samples prepared. According to the results of characterization, Pt/Fe2O3 films were formed on the surface of iron plates, in which platinum was uniformly deposited on the nanotube surfaces. The PEC performance of the samples prepared was evaluated. Higher photocurrent response in photoelectrochemical water splitting was shown by Pt-deposited samples in comparison with the Fe2O3 nanotubes. Moreover, the photoelectrochemical characteristics of the Pt/Fe2O3 films as a function of the photodeposition time were investigated and a maximum photocurrent density of 220 lA/cm2 was shown by sample HPt3. Acknowledgments The author wish to acknowledge the financial support of Iran National Science Foundation (Project No: 93047933). Also, I am so thankful to Isfahan University of Technology for supporting of this research. Appendix A. Supplementary data Supplementary data to this article can be found online at https://doi.org/10.1016/j.matlet.2018.11.089. References
Fig. 3. (a) UV–Vis absorbance spectra of different samples; (b) Photocurrentpotential characteristics of as-deposited samples in 1 0.1 M Na2S and 0.1 M Na2SO3 solutions with chopped light and (c) Photocurrent density-time plots of these samples at +0.4 V vs. Ag/AgCl.
[1] M.C. Huang, W.S. Chang, J.C. Lin, Y.H. Chang, C.C. Wu, J. Alloys Compd. 636 (2015) 176–182. [2] Y.S. Hu, A. Kleiman-Shwarsctein, A.J. Forman, D. Hazen, J.N. Park, E.W. McFarland, Chem. Mater. 20 (2008) 3803–3805. [3] Z. Luo, C. Li, S. Liu, T. Wang, J. Gong, Chem. Sci. 8 (2016) 91–100. [4] S. Wei, D.A. Han, S.C. Walker, Chem. Sci. 3 (2012) 1090–1094. [5] J. Cai, S. Li, H. Pan, Y. Liu, G. Qin, J. Mater. Sci. 51 (2016) 8148–8155. [6] C. Cao, C. Hu, W. Shen, S. Wang, S. Song, M. Wang, Mater. Res. Bull. 70 (2015) 155–162. [7] J. Lin, X. Zhang, L. Zhou, S. Li, G. Qin, Mater Res. Bull. 91 (2017) 214–219. [8] S.Y. Lian, E.B. Wang, Z.H. Kang, Y.P. Bai, L. Gao, M. Jiang, C.W. Hu, L. Xu, Solid State Commun. 129 (2004) 485–490. [9] C.D. Bohn, A.K. Agrawal, E.C. Walter, M.D. Vaudin, A.A. Herzing, P.M. Haney, A. A. Talin, V.A. Szalai, J. Phys. Chem. C 116 (2012) 15290–15296. [10] J.A. Glasscock, P.R. Barnes, I.C. Plumb, N. Savvides, J. Phys. Chem. C 111 (2007) 16477–16488. [11] D. Ding, B. Dong, J. Liang, H. Zhou, Y. Pang, S. Ding, ACS Appl. Mater. Interfaces 8 (2016) 24573–24578. [12] K.D. Malviya, H. Dotan, D. Shlenkevich, A. Tsyganok, H. Mor, A. Rothschild, J. Mater. Chem. A 4 (2016) 3091–3099. [13] Z. Zhang, M.F. Hossain, T. Miyazaki, T. Takahashi, Environ. Sci. Technol. 44 (2010) 4741–4746. [14] M.M. Momeni, Y. Ghayeb, J. Mater. Sci-Mater. El 27 (2016) 1062–1069.
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[15] M.M. Momeni, N. Mohammadi, M. Mirhosseini, J. Mater. Sci-Mater. El 27 (2016) 10147–10156. [16] K. Kim, N. Winograd, R. Davis, J. Am. Chem. Soc. 93 (1971) 6296–6297.
[17] L.A. Marusak, R. Messier, W.B. White, J. Phys. Chem. Solids 41 (1980) 981–984. [18] M.P. Dare-Edwards, J.B. Goodenough, A. Hamnett, P.R. Ravellick, J. Chem. Soc. Faraday Trans. 1 (79) (1983) 2027–2041.
Contents lists available at ScienceDirect
Materials Letters journal homepage: www.elsevier.com/locate/mlblue
Effects of platinum photodeposition time on the photoelectrochemical properties of Fe2O3 nanotube electrodes Mohamad Mohsen Momeni a,⇑, Yousef Ghayeb a, Akbar Hallaj a, Robabeh Bagheri b, Zhenlun Songd b, Hossein Farrokhpour a a
Department of Chemistry, Isfahan University of Technology, Isfahan 84156-83111, Iran Key Laboratory of Marine Materials and Related Technologies, Zhejiang Key Laboratory of Marine Materials and Protective Technologies, Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences, Ningbo 315201, PR China b
a r t i c l e
i n f o
Article history: Received 25 July 2018 Received in revised form 27 October 2018 Accepted 14 November 2018 Available online 15 November 2018 Keywords: Fe2O3 nanotube Platinum Deposition Photoelectrochemical Thin films
a b s t r a c t A photo-assisted deposition method for the deposition of platinum nanoparticles on Fe2O3 nanotubes (Pt/Fe2O3), prepared by anodizing, has been developed. The chemicophysical properties and elemental composition of the synthetic Pt/Fe2O3 samples have also been determined. The investigation of the photoelectrochemical properties of the prepared Pt/Fe2O3 samples showed their greatly increased photocurrent density for photoelectrochemical (PEC) water splitting compared to bare Fe2O3. Therefore, the deposition of Pt is effective on the enhancement of the PEC response. In addition, the effect of the Pt photodeposition time on water splitting capability was studied. The current density produced by sample HPt3 was 220 lA/cm2 at +0.4 V vs. Ag/AgCl, which is 2 times higher than that of the bare Fe2O3 nanotube samples (105 lA/cm2, at +0.4 V vs. Ag/AgCl). Ó 2018 Elsevier B.V. All rights reserved.
1. Introduction Given the relatively narrow band gap (2.0–2.2 eV), low cost, non-toxicity and high chemical stability (photo corrosion) of hematite (a-Fe2O3) in many solvents over a wide pH range and its stability in most electrolytes, it has been of great interest [1–4]. The unique properties of hematite make it a promising candidate as a photoelectrode in photoelectrochemical (PEC) cells. Nevertheless, the strong drawbacks of hematite such as low absorption coefficient, slow charge carrier mobility on the surface, poor electrical conductivity and high photo generated electron hole pair recombination rates, decrease its PEC water splitting efficiency [2–7]. Such disadvantages have to be overcome to improve the solar-to-hydrogen conversion efficiency of hematite. Two different approaches for this purpose include the preparation of nanostructures to increase the contact surface area with electrolytes [8] and prolonging charge lifetime by modification using various metals or catalysts [9]. The electrical conductivity, carrier concentration and optical absorption coefficient of hematite are enhanced by modification of its surface with metals. Many species have been introduced into Fe2O3 [1–7,9–12]. Platinum has attracted the most attention as one of the most effective elements ⇑ Corresponding author. E-mail address: [email protected] (M. Mohsen Momeni). https://doi.org/10.1016/j.matlet.2018.11.089 0167-577X/Ó 2018 Elsevier B.V. All rights reserved.
in this regard due to its noble metal property for catalysis [2,13– 15]. Hu et al. reported the preparation of Pt-doped a-Fe2O3 films by electrodeposition method [2]. Pt layer coated on a-Fe2O3 films were prepared by Zhang et al. through DC facing targets sputtering method and the photocatalytic activity of the film was investigated [13]. Although there are different publications on the preparation methods for Pt/hematite, to the best of the authors’ knowledge, Pt/Fe2O3 nanotube films fabricated by anodizing of iron plate and photochemical deposition of platinum have not yet been reported. A facile photoassisted deposition technique has been used for coating platinum on Fe2O3 nanotubes in this work. SEM, XRD, XPS, EDX and UV–visible have been used for characterization of the samples obtained. The effect of deposited platinum on the photocatalytic activities was explored by carrying out photoelectrochemical measurements. The details on the preparation, characterization and photoelectrochemical testing of Pt/Fe2O3 samples can be found in the Supporting Information. 2. Results and discussion Fig. 1(a) shows the SEM image of the Fe2O3 nanotube films prepared by anodization of iron foil prior to platinum photodeposition. The average inner diameter of the pore is approximately 43 nm and the wall thickness and the length of the tube are about 20 nm and 4 lm, respectively. As observed, the nanotubes are
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Fig. 1. FESEM images of prepared samples in 1 lm scale with 30 KX magnifications; (a) sample H, (b) sample HPt1, (c) sample HPt2, (d) sample HPt3, (e) sample HPt4 and (f) sample HPt5.
arranged orderly and closely with almost uniform diameters and wall thicknesses. Fig. 1b-f show the surface morphologies of the Pt/Fe2O3 samples with the deposition times of 20, 40, 60, 120 and 300 s, respectively. As the increment in the wall thickness shows, platinum nanoparticles have been deposited around the Fe2O3 nanotube wall. After photo deposition of platinum, the tube diameter of HPt1 to HPt5 is 41.98, 39.83, 38.47, 37.45 and 34.90 nm, respectively. A junction layer of the sediment particles have covered the Fe2O3 tube arrays following the photodeposition and the structures obatined are more like porous films. The morphology of the films vary depending on the change of the deposition time. Deposited particles cover the tubes on further increase of the deposition time. Fig. 2a shows the X-ray diffraction (XRD) patterns of the bare Fe2O3 and Pt/Fe2O3 samples. The characteristic peaks at (1 1 1), (2 0 0), (2 2 0) and (3 1 1), associated with platinum, are observed in addition to the intensive Fe2O3 signals at planes (0 2 1), (1 0 4), (1 1 0), (1 1 6), (0 2 4), (1 1 6), (2 1 4), (3 0 0) and (1 1 9), which verify Pt/Fe2O3 formation. The sharp peaks in the recorded XRDs confirms the crystalline structure for the synthesized structures. The XPS surface analysis was carried out to further study the surface
chemical compositions of the Pt/Fe2O3 samples. The survey scan of XPS spectra, indicating the presence of C, Fe, Pt and O, is shown in Fig. 2b. As Fig. 2c shows, the residual carbon is due to the adventitious carbon arising from exposure to air [1]. Two characteristic 2p 3/2 and 2p 1/2 bands of Fe3+ at 712 and 726 eV, respectively, are identified in the high resolution Fe 2p spectrum (Fig. 2d). In addition, a typical Fe3+ satellite peak, typical of a-Fe2O3, is also observed at a binding energy of 718.98 eV. Two peaks are observed at 80 eV (4f 5/2) and 74 eV (4f 7/2) in the Pt 4f spectrum (Fig. 2f), which could be ascribed to PtO2 [16]. The presence of Fe, Pt, C and O, as the only elements in this sample, is shown in EDX spectrum of Pt/Fe2O3 sample (Fig. S2). EDX mapping was used to study the elemental distribution in the Pt/Fe2O3 sample and the corresponding results are shown in the Electronic Supplementary Information. The presence of iron and Pt on the nanotube are confirmed by the EDX mapping shown in Fig. S3. Fig. 3a shows the UV–Vis absorption spectra of bare Fe2O3 and Pt/Fe2O3. Similar absorption features are exhibited by all the films. A peak in the range of 360–480 nm is usually observed, which is characteristic of Fe2O3 films and originates from the indirect Fe 3d to 3d and direct O 2p to Fe 3d transitions [17]. As shown in
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Fig. 2. (a) Typical XRD patterns of the prepared samples; XPS spectra of the Pt/Fe2O3: (b) survey, (c) C 1s, (d) Fe 2p, (e) O 1s and (f) Pt 4f.
figure, the maximum absorption spectrum shifts from 360 nm in bare Fe2O3 to 480 nm in HPt1 sample, but it should be noted that there is no regular trend in absorbance spectral shift of Fe2O3 with various Pt loading. Therefore, a major portion of the light in the visible region can be absorbed by Pt/Fe2O3 samples to produce electron hole pairs, which may in turn give rise to the high photocatalytic activity of these novel samples. Voltammogram experiments have been used to evaluate the photoelectrochemical properties of the samples prepared. The voltograms of photocurrent vs. the applied voltage of different electrodes as a function of the photodeposition time are shown in Fig. 3b. Under illumination, the photocurrent observed is known to be directly related to the water splitting rate, which shows the number of charge carriers produced from the incident light and
their subsequent participation in water oxidation on the photoanode and hydrogen ion reduction on the counter electrode [2]. Under light, a photocurrent of 220 lA/cm2 was observed at +0.4 V potential for HPt3 sample, which is much higher than that of the bare Fe2O3 nanotube sample (105 lA/cm2). The plot of photocurrent density vs. time for various samples at 0.4 V constant potential vs. Ag/AgCl reference electrode under illumination with 50 s light on/off cycle for 300 sec in 0.1 M Na2S and 0.1 M Na2SO3 solutions (pH = 9) is shown in Fig. 3c. Upon illumination, the photocurrent increases at once and remains constant throughout the illumination, but suddenly drops when the light is turned off. The photocurrent response is observed to change with the photodeposition time. Generally speaking, the photocurrents of the samples containing Pt are much higher than those of the samples
M. Mohsen Momeni et al. / Materials Letters 237 (2019) 188–192
191
without Pt (except for sample HPt2). This indicates the participation of a much larger number of photoelectrons in the water splitting reaction. In general, slow surface kinetics has been suggested to induce charge recombination at the Fe2O3 surface [18]. Thus, a possible explanation for the increased photocurrent of Ptdeposited samples is that a catalytic function for water splitting reaction is provided by Pt on the surface of the Fe2O3. Furthermore, platinum deposition may enhance the electric field, leading to higher charge separation efficiency and a large photocurrent density. It must be pointed out that an optimal platinum photodeposition time is required for good photoresponse. 3. Conclusions Porous Pt/Fe2O3 films have been prepared by electrochemical anodizing and photochemical deposition. Highly ordered Fe2O3 nanotubes have been successfully fabricated on pure iron foils via electrochemical anodizing, followed by the deposition of platinum (Pt/Fe2O3) through photodeposition. XRD, FE-SEM, EDS, XPS and UV–Vis absorption spectra were used to systematically characterize all the samples prepared. According to the results of characterization, Pt/Fe2O3 films were formed on the surface of iron plates, in which platinum was uniformly deposited on the nanotube surfaces. The PEC performance of the samples prepared was evaluated. Higher photocurrent response in photoelectrochemical water splitting was shown by Pt-deposited samples in comparison with the Fe2O3 nanotubes. Moreover, the photoelectrochemical characteristics of the Pt/Fe2O3 films as a function of the photodeposition time were investigated and a maximum photocurrent density of 220 lA/cm2 was shown by sample HPt3. Acknowledgments The author wish to acknowledge the financial support of Iran National Science Foundation (Project No: 93047933). Also, I am so thankful to Isfahan University of Technology for supporting of this research. Appendix A. Supplementary data Supplementary data to this article can be found online at https://doi.org/10.1016/j.matlet.2018.11.089. References
Fig. 3. (a) UV–Vis absorbance spectra of different samples; (b) Photocurrentpotential characteristics of as-deposited samples in 1 0.1 M Na2S and 0.1 M Na2SO3 solutions with chopped light and (c) Photocurrent density-time plots of these samples at +0.4 V vs. Ag/AgCl.
[1] M.C. Huang, W.S. Chang, J.C. Lin, Y.H. Chang, C.C. Wu, J. Alloys Compd. 636 (2015) 176–182. [2] Y.S. Hu, A. Kleiman-Shwarsctein, A.J. Forman, D. Hazen, J.N. Park, E.W. McFarland, Chem. Mater. 20 (2008) 3803–3805. [3] Z. Luo, C. Li, S. Liu, T. Wang, J. Gong, Chem. Sci. 8 (2016) 91–100. [4] S. Wei, D.A. Han, S.C. Walker, Chem. Sci. 3 (2012) 1090–1094. [5] J. Cai, S. Li, H. Pan, Y. Liu, G. Qin, J. Mater. Sci. 51 (2016) 8148–8155. [6] C. Cao, C. Hu, W. Shen, S. Wang, S. Song, M. Wang, Mater. Res. Bull. 70 (2015) 155–162. [7] J. Lin, X. Zhang, L. Zhou, S. Li, G. Qin, Mater Res. Bull. 91 (2017) 214–219. [8] S.Y. Lian, E.B. Wang, Z.H. Kang, Y.P. Bai, L. Gao, M. Jiang, C.W. Hu, L. Xu, Solid State Commun. 129 (2004) 485–490. [9] C.D. Bohn, A.K. Agrawal, E.C. Walter, M.D. Vaudin, A.A. Herzing, P.M. Haney, A. A. Talin, V.A. Szalai, J. Phys. Chem. C 116 (2012) 15290–15296. [10] J.A. Glasscock, P.R. Barnes, I.C. Plumb, N. Savvides, J. Phys. Chem. C 111 (2007) 16477–16488. [11] D. Ding, B. Dong, J. Liang, H. Zhou, Y. Pang, S. Ding, ACS Appl. Mater. Interfaces 8 (2016) 24573–24578. [12] K.D. Malviya, H. Dotan, D. Shlenkevich, A. Tsyganok, H. Mor, A. Rothschild, J. Mater. Chem. A 4 (2016) 3091–3099. [13] Z. Zhang, M.F. Hossain, T. Miyazaki, T. Takahashi, Environ. Sci. Technol. 44 (2010) 4741–4746. [14] M.M. Momeni, Y. Ghayeb, J. Mater. Sci-Mater. El 27 (2016) 1062–1069.
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[15] M.M. Momeni, N. Mohammadi, M. Mirhosseini, J. Mater. Sci-Mater. El 27 (2016) 10147–10156. [16] K. Kim, N. Winograd, R. Davis, J. Am. Chem. Soc. 93 (1971) 6296–6297.
[17] L.A. Marusak, R. Messier, W.B. White, J. Phys. Chem. Solids 41 (1980) 981–984. [18] M.P. Dare-Edwards, J.B. Goodenough, A. Hamnett, P.R. Ravellick, J. Chem. Soc. Faraday Trans. 1 (79) (1983) 2027–2041.