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Design of hollow 3D hierarchical microcubes of SnS2 for enhancing photoelectrochemical performance
Materials Letters 257 (2019) 126678
Contents lists available at ScienceDirect
Materials Letters journal homepage: www.elsevier.com/locate/mlblue
Design of hollow 3D hierarchical microcubes of SnS2 for enhancing photoelectrochemical performance Yanghang Song, Hui Liu ⇑, Mengyan Li, Zhao Li School of Materials Science and Engineering, Shaanxi Key Laboratory of Green Preparation and Functionalization for Inorganic Materials, Shaanxi University of Science and Technology, Xi’an 710021, China
a r t i c l e
i n f o
Article history: Received 18 May 2019 Received in revised form 11 August 2019 Accepted 14 September 2019 Available online 16 September 2019 Keywords: Hollow microcubes Hierarchical SnS2 Photoelectrochemical Semiconductors
a b s t r a c t The hollow 3D SnS2 hierarchical microcubes (H-SnS2) constructed by 2D nanoflake subunits were synthesized via a topotactic transformation of co-precipitated hollow ZnSn(OH)6 microcubes (H-ZnSn(OH)6) through hydrothermal treatment. In addition, H-ZnSn(OH)6 not only are used as a reaction reagent but also play a key role as sacrificial template. The morphology and structure of the as-prepared products were well characterized by XRD, FESEM, TEM and HRTEM. Employing a structural optimized technique, the photocurrent density of H-SnS2 of up to 1.4 lA cm 2 at 1.23 V (vs. RHE) under simulated solar light irradiation has been achieved, and this can open a new way to enhance the performance of photoelectrochemical water splitting through the design of new structure. Ó 2019 Elsevier B.V. All rights reserved.
1. Introduction Energy consumption and environmental pollution have been gained more attention in recent years [1–3]. Therefore, it is extremely urgent to find an environment-friendly and resource-rich energy source. Solar energy, as a rich, clean, green and harmless renewable energy, has become a research hotspot in many related fields. Semiconductor photoelectrocatalysis materials are the key to absorbing and transforming solar energy [4,5]. Thus, finding cheap and efficient semiconductor materials are one of the key ways to achieve efficient solar energy conversion and utilization. Tin (IV) disulfide (SnS2) is an important semiconductor with layered CdI2-type structure, which has been widely studied and applied in various fields due to its interesting properties and a wide variety of potential applications [6–10]. Hollow structures with distinct structural and geometrical features of the large high specific surface area, high porosity, and internal void space can make full use of the inner-shell layer, and enhance the interaction between the electrolyte and the material [11,12]. In addition, hierarchical structures can avoid the aggregation of nanomaterials and increase the light capture. However, to the best of our knowledge, there have been no reports on the synthesis of 3D hierarchical microcube-type SnS2 hollow materials for performance of photoelectrochemical water splitting. ⇑ Corresponding author. E-mail address: [email protected] (H. Liu). https://doi.org/10.1016/j.matlet.2019.126678 0167-577X/Ó 2019 Elsevier B.V. All rights reserved.
Herein, we report the synthesis of the hollow 3D SnS2 hierarchical microcubes (H-SnS2) consisting of 2D SnS2 nanoflakes under hydrothermal condition by converting the hollow ZnSn(OH)6 microcubes at 220 °C for 12 h. The novelty of the present study is related to the new synthesis strategy to generate H-SnS2 by a facile co-precipitation reaction followed by a topotactic transformation in the presence of TAA and H4EDTA through a hydrothermal process. The construction of H-SnS2 samples is beneficial to improve the performance of photoelectrochemical water splitting.
2. Experimental 2.1. Synthesis of hollow ZnSn(OH)6 microcubes All chemicals were of analytical purity and used without further purification. Firstly, 5 mL of ethanol solution of SnCl45H2O (1.0 mmol) was added into 10 mL of a mixed solution containing ZnCl2 (1.0 mmol) and citric acid (1.0 mmol). After stirring for 10 min, 25 mL NaOH solution (0.5 M) was added quickly into the above solution. Subsequently, 20 mL NaOH solution (2 M) was dropped into the suspension with stirring for 10 min. The white products were collected and washed with deionized water and ethanol, and dried under vacuum at 60 °C, and marked H-ZnSn(OH)6. For comparison, solid ZnSn(OH)6 microcubes were obtained by the same experimental method without NaOH solution (20 mL, 2 M), and was denoted as S-ZnSn(OH)6.
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2.2. Synthesis of hollow 3D SnS2 hierarchical microcubes H-ZnSn(OH)6 (1 mmol), thioacetamide (TAA, 5 mmol) and ethylenediaminetetraacetic acid (H4EDTA, 4 mmol) were added into deionized water (60 mL) under stirring and ultrasonic treatment. The resulting solution was transferring into a 100 mL Teflon-lined stainless steel autoclave and heated at 220 °C for 12 h. After the autoclave cooling to room temperature naturally, the as-prepared product was collected and washed with deionized water and ethanol, and dried under vacuum at 60 °C, and marked as H-SnS2. 2.3. Characterization The crystal structures of the samples were conducted on an Xray diffractometer (XRD-D/max 2200, Japan, Cu-Ka 0.154 nm). Field emission scanning electron microscopy (FESEM, S-4800, Hitachi) and a transmission electron microscope (TEM, JEM-2010, JEOL Japan) analyses were used to determine the particle size and morphology. 2.4. Photoelectrochemical characterizations All measurements were carried out on a CHI660D electrochemical workstation using the samples as the working electrode, a Pt wire as the counter electrode and a saturated calomel electrode (SCE) as the reference electrode in 0.2 M Na2SO4 aqueous solution. The preparation of working electrode can be seen Supplementary Data for details. In all measurements, the potentials were calculated with respect to reversible hydrogen electrode (RHE) based on the following equation: E(RHE) = E(SCE) + 0.0591 pH + 0.2412 V. All the potentials are referred to RHE without specification. Photocurrent response, linear sweep voltammograms (LSV) and Electrochemical impedance spectroscopy (EIS) tests were carried out by a standard three-electrode setup. 3. Results and discussion The hollow 3D hierarchical microcubes of SnS2 are facilely fabricated through a facile co-precipitation method and topotactic transformation process as shown Scheme 1. The synthetic process on details can be seen Supplementary Data. In step (1), S-ZnSn (OH)6 could be obtained through co-precipitation method. The formation of H-ZnSn(OH)6 is caused by the addition of the high concentration of alkali etching solution in step (2). The typical XRD pattern of H-ZnSn(OH)6 (black line) shows in Fig. 1. All the diffraction peaks can be assigned to the cubic of ZnSn(OH)6 (JCPDS No. 20-1455), and no diffraction peaks of impurities are observed, indicating high purity and good crystallinity. Lastly, H-SnS2 samples
Fig. 1. XRD patterns of H-ZnSn(OH)6 (black line) and H-SnS2 (red line) samples. (For interpretation of the references to colour in this figure legend, the reader is referred to the web version of this article.)
were formed in the presence of TAA and H4EDTA by hydrothermal treatment in step (3). In the hydrothermal process, H-ZnSn(OH)6 not only are used as a reaction reagent but also play a key role as sacrificial template [9]. Likewise, XRD pattern of H-SnS2 (red line) is indexed as the 2 T-type hexagonal SnS2 (JCPDS No. 230677) without detectable impurity, indicating the high purity and crystallinity. The FESEM image in Fig. 2(a) shows that S-ZnSn(OH)6 have cubic morphology with slightly rounded corners and uniform size with an average edge size of 2.8 lm. Fig. 2(b) show that the typical FESEM image of H-ZnSn(OH)6 samples with an average edge size of 2.8 lm and the wall thickness of 200–400 nm show a broken hole, which can confirm the presence of a hollow interior. And from TEM image in Fig. 2(c) can see that the pale regions in the center of the individual particle is brighter than the edge, which further confirms that H-ZnSn(OH)6 are indeed hollow and have a wall thickness of 230 nm. Fig. 2(d) shows the corresponding HRTEM image, displaying the resolved lattice fringes of (2 0 0) planes (d = 0.391 nm). The FESEM image in Fig. 2(e) clearly shows the hollow 3D SnS2 hierarchical microcubes with self-assembling of 2D nanoflakes. The thickness of these 2D nanoflake subunits is 30 nm in Fig. 2(f). From the TEM image in Fig. 2(g) is also observed that the pale regions in the center of the individual particle are brighter than the edge, which can confirm the hollow of 3D SnS2 hierarchical microcubes. Fig. 2(h) shows the corresponding HRTEM image of H-SnS2, the obvious lattice fringes with interplanar d-spacing of 0.316 and 0.589 nm are well consistent with plane (1 0 0) and (0 0 1) of hexagonal-phase SnS2, respectively, and inset FFT images indicate that SnS2 nanoflake grow along
Scheme 1. Schematic illustration of the as-prepared samples.
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Fig. 2. FESEM images of S-ZnSn(OH)6 (a), H-ZnSn(OH)6 (b) and H-SnS2 (e, f) samples, insets: the size distribution figure of samples; TEM and HRTEM images of H-ZnSn(OH)6 (c, d) and H-SnS2 (g, h) samples (insets: FFT images).
(1 0 0) direction. These above results show that H-ZnSn(OH)6, acted as sacrificial template and reaction reagent, have successfully converted into H-SnS2 after hydrothermal treatment. The performance of photoelectrochemical water splitting of the samples was tested in a 0.2 M Na2SO4 electrolyte using a standard three-electrode system. It is well known that the photocurrent
density is closely related to its photoelectrocatalytic performance in the photoelectrocatalytic reaction process. The transient photocurrent measurement of H-SnS2 catalyst is studied under simulated solar light illumination. The photocurrent densities of these materials show regular fluctuations along the interval of simulated solar light illumination in Fig. 3(a). For comparison, SnS2
Fig. 3. The Photocurrent response (a), Linear sweep voltammetry (b) curves of H-SnS2 and SnS2 NSs in 0.2 M Na2SO4 (scan rate: 10 mV s portions (d) of Nyquist plots at high frequency region of H-SnS2 and SnS2 NSs.
1
); Nyquist plots (c) and magnified
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nanosheets (SnS2 NSs) were also tested. It can be clearly observed from Fig. 3(a) that H-SnS2 electrode exhibits a higher photocurrent density of about 1.4 lA cm 2, which is 7 times that of SnS2 NSs. Fig. 3(b) shows linear sweep voltammetry curves of H-SnS2 and SnS2 NSs under dark and light conditions (scan rate: 10 mV s 1). The photocurrent density at 1.23 V (vs. RHE, the theoretical potential value for splitting water) is an important parameter for evaluating the photoelectrocatalytic performance of water splitting [13,14]. It can be seen from Fig. 3(b) that the photocurrent density at 1.23 V (vs. RHE) is in descending order: H-SnS2 (light), H-SnS2 (dark), SnS2 NSs (light), SnS2 NSs (dark). From Fig. 3(c, d) show that the arc radius of H-SnS2 are smaller than the other samples under both dark and light, indicating that the interface charge transfer resistance of H-SnS2 is the smallest, which promotes the charge transfer and reduces the recombination rate of photogenerated electrons and holes. As all known, the surface area of the working electrode contains the same mass (1.33 mg per 4 cm2) of catalyst, so the following conclusions can be drawn: the construction of the 3D SnS2 hollow hierarchical nanostructure facilitates more light trapping and contact reaction site between electrolytes and catalytic to promote the generation, separation and transfer of photogenerated electrons, which is beneficial to improve the performance of photoelectrochemical water splitting. 4. Conclusions In summary, the hollow 3D SnS2 hierarchical microcubes consisting of 2D nanoflake subunits have been successfully synthesized via a facile co-precipitation method and followed by topotactic transformation through a hydrothermal treatment. The construction of the 3D SnS2 hollow hierarchical nanostructural material is beneficial to improve the performance of photoelectrochemical water splitting.
Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper. Acknowledgments This work was supported by the National Science Foundation of China (51272147), the Natural Science Foundation of Shaanxi Province (2015JM5208) and the Graduate Innovation Found of Shaanxi University of Science and Technology. Appendix A. Supplementary data Supplementary data to this article can be found online at https://doi.org/10.1016/j.matlet.2019.126678. References [1] L. Hongjin, Y.V. Geletii, Z. Chongchao, et al., Chem. Soc. Rev. 41 (22) (2012) 7572–7589. [2] S. Chu, A. Majumdar, Nature 488 (7411) (2012) 294–303. [3] J. Liu, Y. Wang, J. Ma, et al., J. Alloys Compd. 783 (2019) 898–918. [4] G. Mohan Kumar, H.D. Cho, P. Ilanchezhiyan, et al., J. Colloid Interface Sci. 540 (2019) 476–485. [5] J. Mu, H. Miao, E. Liu, et al., Ceram. Int. 43 (6) (2017) 4992–5001. [6] Y. Liu, Y. Zhang, D. Wu, et al., Biosens. Bioelectron. 86 (2016) 301–307. [7] Y. Wang, D. Fan, G. Zhao, et al., Biosens. Bioelectron. 120 (2018) 1–7. [8] J. Xia, G. Li, Y. Mao, et al., CrystEngComm 14 (13) (2012) 4279–4283. [9] P. Cai, D.-K. Ma, Q.-C. Liu, et al., J. Mater. Chem. A 1 (17) (2013) 5217–5223. [10] G. Liu, Z. Li, T. Hasan, et al., J. Mater. Chem. A 5 (5) (2017) 1989–1995. [11] X. Wang, J. Feng, Y. Bai, et al., Chem. Rev. 116 (18) (2016) 10983–11060. [12] J. Wang, C. Xue, W. Yao, et al., Appl. Catal. B-Environ. 250 (2019) 369–381. [13] S. Hernández, G. Gerardi, K. Bejtka, et al., Appl. Catal. B-Environ. 190 (2016) 66–74. [14] L. Guo, J. Li, N. Lei, et al., J. Alloys Compd. 771 (2019) 914–923.
Contents lists available at ScienceDirect
Materials Letters journal homepage: www.elsevier.com/locate/mlblue
Design of hollow 3D hierarchical microcubes of SnS2 for enhancing photoelectrochemical performance Yanghang Song, Hui Liu ⇑, Mengyan Li, Zhao Li School of Materials Science and Engineering, Shaanxi Key Laboratory of Green Preparation and Functionalization for Inorganic Materials, Shaanxi University of Science and Technology, Xi’an 710021, China
a r t i c l e
i n f o
Article history: Received 18 May 2019 Received in revised form 11 August 2019 Accepted 14 September 2019 Available online 16 September 2019 Keywords: Hollow microcubes Hierarchical SnS2 Photoelectrochemical Semiconductors
a b s t r a c t The hollow 3D SnS2 hierarchical microcubes (H-SnS2) constructed by 2D nanoflake subunits were synthesized via a topotactic transformation of co-precipitated hollow ZnSn(OH)6 microcubes (H-ZnSn(OH)6) through hydrothermal treatment. In addition, H-ZnSn(OH)6 not only are used as a reaction reagent but also play a key role as sacrificial template. The morphology and structure of the as-prepared products were well characterized by XRD, FESEM, TEM and HRTEM. Employing a structural optimized technique, the photocurrent density of H-SnS2 of up to 1.4 lA cm 2 at 1.23 V (vs. RHE) under simulated solar light irradiation has been achieved, and this can open a new way to enhance the performance of photoelectrochemical water splitting through the design of new structure. Ó 2019 Elsevier B.V. All rights reserved.
1. Introduction Energy consumption and environmental pollution have been gained more attention in recent years [1–3]. Therefore, it is extremely urgent to find an environment-friendly and resource-rich energy source. Solar energy, as a rich, clean, green and harmless renewable energy, has become a research hotspot in many related fields. Semiconductor photoelectrocatalysis materials are the key to absorbing and transforming solar energy [4,5]. Thus, finding cheap and efficient semiconductor materials are one of the key ways to achieve efficient solar energy conversion and utilization. Tin (IV) disulfide (SnS2) is an important semiconductor with layered CdI2-type structure, which has been widely studied and applied in various fields due to its interesting properties and a wide variety of potential applications [6–10]. Hollow structures with distinct structural and geometrical features of the large high specific surface area, high porosity, and internal void space can make full use of the inner-shell layer, and enhance the interaction between the electrolyte and the material [11,12]. In addition, hierarchical structures can avoid the aggregation of nanomaterials and increase the light capture. However, to the best of our knowledge, there have been no reports on the synthesis of 3D hierarchical microcube-type SnS2 hollow materials for performance of photoelectrochemical water splitting. ⇑ Corresponding author. E-mail address: [email protected] (H. Liu). https://doi.org/10.1016/j.matlet.2019.126678 0167-577X/Ó 2019 Elsevier B.V. All rights reserved.
Herein, we report the synthesis of the hollow 3D SnS2 hierarchical microcubes (H-SnS2) consisting of 2D SnS2 nanoflakes under hydrothermal condition by converting the hollow ZnSn(OH)6 microcubes at 220 °C for 12 h. The novelty of the present study is related to the new synthesis strategy to generate H-SnS2 by a facile co-precipitation reaction followed by a topotactic transformation in the presence of TAA and H4EDTA through a hydrothermal process. The construction of H-SnS2 samples is beneficial to improve the performance of photoelectrochemical water splitting.
2. Experimental 2.1. Synthesis of hollow ZnSn(OH)6 microcubes All chemicals were of analytical purity and used without further purification. Firstly, 5 mL of ethanol solution of SnCl45H2O (1.0 mmol) was added into 10 mL of a mixed solution containing ZnCl2 (1.0 mmol) and citric acid (1.0 mmol). After stirring for 10 min, 25 mL NaOH solution (0.5 M) was added quickly into the above solution. Subsequently, 20 mL NaOH solution (2 M) was dropped into the suspension with stirring for 10 min. The white products were collected and washed with deionized water and ethanol, and dried under vacuum at 60 °C, and marked H-ZnSn(OH)6. For comparison, solid ZnSn(OH)6 microcubes were obtained by the same experimental method without NaOH solution (20 mL, 2 M), and was denoted as S-ZnSn(OH)6.
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2.2. Synthesis of hollow 3D SnS2 hierarchical microcubes H-ZnSn(OH)6 (1 mmol), thioacetamide (TAA, 5 mmol) and ethylenediaminetetraacetic acid (H4EDTA, 4 mmol) were added into deionized water (60 mL) under stirring and ultrasonic treatment. The resulting solution was transferring into a 100 mL Teflon-lined stainless steel autoclave and heated at 220 °C for 12 h. After the autoclave cooling to room temperature naturally, the as-prepared product was collected and washed with deionized water and ethanol, and dried under vacuum at 60 °C, and marked as H-SnS2. 2.3. Characterization The crystal structures of the samples were conducted on an Xray diffractometer (XRD-D/max 2200, Japan, Cu-Ka 0.154 nm). Field emission scanning electron microscopy (FESEM, S-4800, Hitachi) and a transmission electron microscope (TEM, JEM-2010, JEOL Japan) analyses were used to determine the particle size and morphology. 2.4. Photoelectrochemical characterizations All measurements were carried out on a CHI660D electrochemical workstation using the samples as the working electrode, a Pt wire as the counter electrode and a saturated calomel electrode (SCE) as the reference electrode in 0.2 M Na2SO4 aqueous solution. The preparation of working electrode can be seen Supplementary Data for details. In all measurements, the potentials were calculated with respect to reversible hydrogen electrode (RHE) based on the following equation: E(RHE) = E(SCE) + 0.0591 pH + 0.2412 V. All the potentials are referred to RHE without specification. Photocurrent response, linear sweep voltammograms (LSV) and Electrochemical impedance spectroscopy (EIS) tests were carried out by a standard three-electrode setup. 3. Results and discussion The hollow 3D hierarchical microcubes of SnS2 are facilely fabricated through a facile co-precipitation method and topotactic transformation process as shown Scheme 1. The synthetic process on details can be seen Supplementary Data. In step (1), S-ZnSn (OH)6 could be obtained through co-precipitation method. The formation of H-ZnSn(OH)6 is caused by the addition of the high concentration of alkali etching solution in step (2). The typical XRD pattern of H-ZnSn(OH)6 (black line) shows in Fig. 1. All the diffraction peaks can be assigned to the cubic of ZnSn(OH)6 (JCPDS No. 20-1455), and no diffraction peaks of impurities are observed, indicating high purity and good crystallinity. Lastly, H-SnS2 samples
Fig. 1. XRD patterns of H-ZnSn(OH)6 (black line) and H-SnS2 (red line) samples. (For interpretation of the references to colour in this figure legend, the reader is referred to the web version of this article.)
were formed in the presence of TAA and H4EDTA by hydrothermal treatment in step (3). In the hydrothermal process, H-ZnSn(OH)6 not only are used as a reaction reagent but also play a key role as sacrificial template [9]. Likewise, XRD pattern of H-SnS2 (red line) is indexed as the 2 T-type hexagonal SnS2 (JCPDS No. 230677) without detectable impurity, indicating the high purity and crystallinity. The FESEM image in Fig. 2(a) shows that S-ZnSn(OH)6 have cubic morphology with slightly rounded corners and uniform size with an average edge size of 2.8 lm. Fig. 2(b) show that the typical FESEM image of H-ZnSn(OH)6 samples with an average edge size of 2.8 lm and the wall thickness of 200–400 nm show a broken hole, which can confirm the presence of a hollow interior. And from TEM image in Fig. 2(c) can see that the pale regions in the center of the individual particle is brighter than the edge, which further confirms that H-ZnSn(OH)6 are indeed hollow and have a wall thickness of 230 nm. Fig. 2(d) shows the corresponding HRTEM image, displaying the resolved lattice fringes of (2 0 0) planes (d = 0.391 nm). The FESEM image in Fig. 2(e) clearly shows the hollow 3D SnS2 hierarchical microcubes with self-assembling of 2D nanoflakes. The thickness of these 2D nanoflake subunits is 30 nm in Fig. 2(f). From the TEM image in Fig. 2(g) is also observed that the pale regions in the center of the individual particle are brighter than the edge, which can confirm the hollow of 3D SnS2 hierarchical microcubes. Fig. 2(h) shows the corresponding HRTEM image of H-SnS2, the obvious lattice fringes with interplanar d-spacing of 0.316 and 0.589 nm are well consistent with plane (1 0 0) and (0 0 1) of hexagonal-phase SnS2, respectively, and inset FFT images indicate that SnS2 nanoflake grow along
Scheme 1. Schematic illustration of the as-prepared samples.
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Fig. 2. FESEM images of S-ZnSn(OH)6 (a), H-ZnSn(OH)6 (b) and H-SnS2 (e, f) samples, insets: the size distribution figure of samples; TEM and HRTEM images of H-ZnSn(OH)6 (c, d) and H-SnS2 (g, h) samples (insets: FFT images).
(1 0 0) direction. These above results show that H-ZnSn(OH)6, acted as sacrificial template and reaction reagent, have successfully converted into H-SnS2 after hydrothermal treatment. The performance of photoelectrochemical water splitting of the samples was tested in a 0.2 M Na2SO4 electrolyte using a standard three-electrode system. It is well known that the photocurrent
density is closely related to its photoelectrocatalytic performance in the photoelectrocatalytic reaction process. The transient photocurrent measurement of H-SnS2 catalyst is studied under simulated solar light illumination. The photocurrent densities of these materials show regular fluctuations along the interval of simulated solar light illumination in Fig. 3(a). For comparison, SnS2
Fig. 3. The Photocurrent response (a), Linear sweep voltammetry (b) curves of H-SnS2 and SnS2 NSs in 0.2 M Na2SO4 (scan rate: 10 mV s portions (d) of Nyquist plots at high frequency region of H-SnS2 and SnS2 NSs.
1
); Nyquist plots (c) and magnified
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Y. Song et al. / Materials Letters 257 (2019) 126678
nanosheets (SnS2 NSs) were also tested. It can be clearly observed from Fig. 3(a) that H-SnS2 electrode exhibits a higher photocurrent density of about 1.4 lA cm 2, which is 7 times that of SnS2 NSs. Fig. 3(b) shows linear sweep voltammetry curves of H-SnS2 and SnS2 NSs under dark and light conditions (scan rate: 10 mV s 1). The photocurrent density at 1.23 V (vs. RHE, the theoretical potential value for splitting water) is an important parameter for evaluating the photoelectrocatalytic performance of water splitting [13,14]. It can be seen from Fig. 3(b) that the photocurrent density at 1.23 V (vs. RHE) is in descending order: H-SnS2 (light), H-SnS2 (dark), SnS2 NSs (light), SnS2 NSs (dark). From Fig. 3(c, d) show that the arc radius of H-SnS2 are smaller than the other samples under both dark and light, indicating that the interface charge transfer resistance of H-SnS2 is the smallest, which promotes the charge transfer and reduces the recombination rate of photogenerated electrons and holes. As all known, the surface area of the working electrode contains the same mass (1.33 mg per 4 cm2) of catalyst, so the following conclusions can be drawn: the construction of the 3D SnS2 hollow hierarchical nanostructure facilitates more light trapping and contact reaction site between electrolytes and catalytic to promote the generation, separation and transfer of photogenerated electrons, which is beneficial to improve the performance of photoelectrochemical water splitting. 4. Conclusions In summary, the hollow 3D SnS2 hierarchical microcubes consisting of 2D nanoflake subunits have been successfully synthesized via a facile co-precipitation method and followed by topotactic transformation through a hydrothermal treatment. The construction of the 3D SnS2 hollow hierarchical nanostructural material is beneficial to improve the performance of photoelectrochemical water splitting.
Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper. Acknowledgments This work was supported by the National Science Foundation of China (51272147), the Natural Science Foundation of Shaanxi Province (2015JM5208) and the Graduate Innovation Found of Shaanxi University of Science and Technology. Appendix A. Supplementary data Supplementary data to this article can be found online at https://doi.org/10.1016/j.matlet.2019.126678. References [1] L. Hongjin, Y.V. Geletii, Z. Chongchao, et al., Chem. Soc. Rev. 41 (22) (2012) 7572–7589. [2] S. Chu, A. Majumdar, Nature 488 (7411) (2012) 294–303. [3] J. Liu, Y. Wang, J. Ma, et al., J. Alloys Compd. 783 (2019) 898–918. [4] G. Mohan Kumar, H.D. Cho, P. Ilanchezhiyan, et al., J. Colloid Interface Sci. 540 (2019) 476–485. [5] J. Mu, H. Miao, E. Liu, et al., Ceram. Int. 43 (6) (2017) 4992–5001. [6] Y. Liu, Y. Zhang, D. Wu, et al., Biosens. Bioelectron. 86 (2016) 301–307. [7] Y. Wang, D. Fan, G. Zhao, et al., Biosens. Bioelectron. 120 (2018) 1–7. [8] J. Xia, G. Li, Y. Mao, et al., CrystEngComm 14 (13) (2012) 4279–4283. [9] P. Cai, D.-K. Ma, Q.-C. Liu, et al., J. Mater. Chem. A 1 (17) (2013) 5217–5223. [10] G. Liu, Z. Li, T. Hasan, et al., J. Mater. Chem. A 5 (5) (2017) 1989–1995. [11] X. Wang, J. Feng, Y. Bai, et al., Chem. Rev. 116 (18) (2016) 10983–11060. [12] J. Wang, C. Xue, W. Yao, et al., Appl. Catal. B-Environ. 250 (2019) 369–381. [13] S. Hernández, G. Gerardi, K. Bejtka, et al., Appl. Catal. B-Environ. 190 (2016) 66–74. [14] L. Guo, J. Li, N. Lei, et al., J. Alloys Compd. 771 (2019) 914–923.