Hydrothermal synthesis of In2O3 nanoparticles hybrid twins hexagonal disk ZnO heterostructures for enhanced photocatalytic activities and stability
© The Author(s). 2017
Received: 11 April 2017
Accepted: 16 July 2017
Published: 25 July 2017
In2O3 nanoparticles hybrid twins hexagonal disk (THD) ZnO with different ratios were fabricated by a hydrothermal method. The as-obtained ZnO/In2O3 composites are constituted by hexagonal disks ZnO with diameters of about 1 μm and In2O3 nanoparticles with sizes of about 20–50 nm. With the increase of In2O3 content in ZnO/In2O3 composites, the absorption band edges of samples shifted from UV to visible light region. Compared with pure ZnO, the ZnO/In2O3 composites show enhanced photocatalytic activities for degradation of methyl orange (MO) and 4-nitrophenol (4-NP) under solar light irradiation. Due to suitable alignment of their energy band-gap structure of the In2O3 and ZnO, the formation of type п heterostructure can enhance efficient separation of photo-generate electro-hole pairs and provides convenient carrier transfer paths.
In recent years, environmental pollution and energy shortage have created serious social and economic issues for human society. Semiconductor-based photocatalysis has been widely employed as a highly efficient technique to overcome these issues [1–3]. Among these semiconductor metal oxides, zinc oxide (ZnO) has been recognized as a promising photocatalyst owing to its outstanding electrical and optical properties, low cost, high biological safety, versatile shapes and structures, environment benign and strong photocatalytic degradation ability of organic pollutants under UV light. However, ZnO with a wide band gap (Eg = 3.3 eV) can only be activated by ultraviolet (UV) light, which restricts its practical applications for solar energy [4–8]. Another main drawback of ZnO is rapid recombination of photo-induced electron-hole pairs, which results in the low quantum yield for any photocatalytic reactions [9–12]. Therefore, how to extend absorption edge of ZnO to visible light region for the utilization of about 43% solar spectrum meanwhile suppress the photo-generated electron-hole pairs recombination is still a great challenge for scientists. Various modification strategies to activate ZnO photocatalysis under visible light have been employed in the past few years, including sensitization, semiconductor coupling and doping. An efficient strategy is coupling ZnO with another narrowband-gap semiconductor (e.g. CdS , CdSe , Cu2O , C3N4 , ZnFe2O4 , Ag3PO4 , CuInS2 , AgBr  and BiVO4 ) to form ZnO/narrow-band-conductor type п heterostructures. The formation of type II heterostructures has been recognized as an attractive route to overcome the limitations of ZnO because it promotes efficient charge separation, enlarges the effective contact interfaces and improves the optical absorption [22, 23].
In2O3 with a band gap of 2.56 eV has been proved as efficient sensitizer to extent the light absorption spectra by coupling other semiconductor. Also, its valence and conduction band alignments are staggered relative to those of ZnO [24, 25]. A lot of researches on In2O3-ZnO composite have been reported for degradation of organic compounds and hydrogen production by photocatalysis [26–28]. These results show that the incorporation of In2O3 in ZnO nanostructure can remarkably inhibit recombination of photo-generated electron-hole pairs and thus improve the photocatalytic activity. To the best of our knowledge, there has rarely been reported on the fabrication and improvement ZnO photocatalytic activities and stability by In2O3 nanoparticles hybrid.
In this paper, In2O3 nanoparticles hybrid THD ZnO with different ratios were fabricated by a hydrothermal method. The microstructure and optical properties of ZnO/In2O3 heterostructures were examined. The photocatalytic activity and photo-stability of ZnO/In2O3 composites were evaluated by MO and 4-NP under light irradiation. Finally, the charge transfer and probable photocatalytic mechanism have been discussed and proposed on the basis of optical characterization, band gap structure and reactive species reaction.
Formation of ZnO/In2O3 heterostructure
First, 0.1 mol of ZnAc and a specific molar of In(NO 3 ) 2 with a designed atom percent of In to Zn (about 2.0, 5.0, 8.0, 12.0 and 15.0 atom%) were dissolved in 50 ml deionized water to form a clear solution. Then, 15 ml of triethanolamine (TEA) was dropwise into the above solution under magnetically stirring. After that, the mixed solution was heated at 90 °C for 4 h, the obtained precipitates were centrifuged and washed by deionized water and ethanol for several times and dried in an oven at 60 °C. The final ZnO/In2O3 composites were thus obtained by annealing at 200 °C for 1 h. According to the In/Zn molar ratios of 0, 2, 5, 8, 12 and 15%, the composites were marked as Zn-In-0, Zn-In-1, Zn-In-2, Zn-In-3, Zn-In-4 and Zn-In-5, respectively. For comparison, pure In2O3 were also fabricated under the same condition.
The crystal structures were studied by powder X-ray diffraction (XRD) with a 0.154178 nm Cu-Kα radiation. The morphologies and size of the ZnO/In2O3 composites were measured by field emission scanning electron microscopy (FESEM; JSM-6700F, Japan). Chemical compositions were analyzed by X-ray energy-dispersive spectroscopy (EDS) equipped to the SEM. The detailed microstructures of samples were characterized by high resolution transmission electron microscopy (FE-SEM SUPRA™ 40). Chemical states of the samples were analyzed using X-ray photoelectron spectroscopy (XPS; PHI-5300, ESCA, USA). The UV-vis diffused reflectance spectra (UV-vis DRS) of samples were measured on a UV-3600 spectrophotometer. Photoluminescence (PL; Renishaw1000, UK) spectra were measured at room temperature using a He-Cd laser as the excitation light source at 325 nm. The •OH-trapping PL spectra was collected in 5 * 10−3 M terephthalic acid solutions containing 0.01 M NaOH solution with different irradiation time; the excitation wavelength was 325 nm.
The photocatalytic activities of the as-prepared samples were evaluated by the photocatalytic degradation of MO and 4-NP. The wavelength distribution of Xenon lamp was similar to that of solar light; thus, a 500 W Xenon lamp was employed as the light source. For each photocatalytic activity measurement, typically, 10 mg of the photocatalyst was dispersed in 50 ml of MO (5 mg/l) or 4-NP (1 mg/l) aqueous solution and then stirred in the dark for 30 min to achieve an adsorption-desorption equilibrium. The photocatalytic reaction was carried out by Xenon lamp as the solar light source with continuous stirring. At the given intervals, 3 mL of the aliquots was sampled and analyzed by recording variations in the absorption band (464 and 317 nm) in the UV-vis spectra of MO or 4-NP, respectively. To probe the photo-stability of the Zn-In-4 catalyst, cycle degradation was carried out. In this case, Zn-In-4 was repeatedly used, which was separated and collected by centrifugation. After being washed with water and ethanol for several times and dried at 60 °C overnight, the Zn-In-4 catalyst was reused with a fresh MO aqueous solution (5 mg/l) for subsequent reactions under the identical conditions.
Trapping experiments were performed to probe the main active species in the photocatalytic process. The experimental apparatus and procedures were identical to that of the photocatalytic activity tests except that different types of scavengers (1 mM) were added into the MO solution. Herein, a fluorescence technique was employed to detect the formation of free hydroxyl radicals (•OH) and terephthalic acid (TPA) was used as the probe molecule. In detail, the as-synthesized Zn-In-4 (0.025 g) was dispersed into 50 mL mixed solution of 0.25 mmol TPA and 1 mmol NaOH under magnetically stirring. After Xenon lamp (500 W) irradiation for 90 min, the supernatant of reaction solution was collected and examined by a FP-6500 fluorescence spectrophotometer with an excitation wavelength of 315 nm.
Results and discussion
Morphology and phase structure analysis
Weights and atomic percentages of elements in ZnO/In2O3 composites
As we all known, the mass ratio of components has a great effect on the photocatalytic performance in heterostructural photocatalyst system [27, 36]. With mass ratio increasing of In2O3 in ZnO/In2O3 composites, there was no significant difference in the degradation tendency of MO and 4-NP, and appears the maximum degradation efficiency for the sample Zn-In-4. However, PL intensities of the samples show an opposite variation tendency. This result indicates that an appropriate amount of In2O3 in the composites was beneficial to the fast separation of photo-generated charge carriers and thus enhanced the photocatalytic activity [5, 37].
Proposed photocatalytic mechanism
In summary, In2O3 nanoparticles hybrid THD ZnO with different ratios were fabricated via the hydrothermal process. Significantly, compared with pure ZnO, the fabricated ZnO/In2O3 exhibits much better photocatalytic activities for the degradation of MO and 4-NP under simulated solar light irradiation, which can be ascribed to the synergetic effect between ZnO and In2O3, including the maximum heterostructure interface with intimate contact and excellent solar light response in the composite, which both can enhanced photogenerated charge separation efficiency. This work could give insights into the importance of rational design of heterostructure systems and provide a potential method for the construction of efficient heterostructure photocatalysts with controllable sizes and space distributions.
This work was supported by the National Natural Science Foundation of China (No. 51502081); Basic and Frontier Research Programs of Henan Province (No. 152300410088).
HL carried the main part of the experimental work and XRD measurements. HZ carried the XPS tests. CH and JY participated in the preparation of the samples. ZL carried SEM images measurements. All authors read and approved the final manuscript.
The authors declare that they have no competing interests.
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- Cao SW, Low JX, Yu JG, Jaroniec M (2015) Polymeric photocatalysts based on graphitic carbon nitride. Adv Mater 27:2150–2176View ArticleGoogle Scholar
- Wenderich K, Mul G (2016) Methos, mechanism, and applications of photodeposition in photocatalysis: a review. Chem Rev 116:14587–14619View ArticleGoogle Scholar
- Li K, Peng BS, Peng TY (2016) Recent advances in heterogeneous photocatalytic CO2 conversion to solar fuels. ACS Catal 6:7485–7527View ArticleGoogle Scholar
- Wang CL, Tan X, Yan JT, Chai B, Li JF, Chen SZ (2017) Electrospinning direct synthesis of magnetic ZnFe2O4/ZnO multi-porous nanotubes with enhanced photocatalytic activity. Appl Surf Sci 396:780–790View ArticleGoogle Scholar
- Hong DY, Zang WL, Guo MX, Fu YM, He HX, Sun J, Xing LL, Liu BD, Xue XY (2016) High piezo-photocatalytic efficiency of CuS/ZnO nanowires using both solar and mechanical energy for degrading organic dye. ACS Appl Mater Interfaces 8:21302–21314View ArticleGoogle Scholar
- Liang YC, Lee CM (2016) Cosputtering crystal growth of zinc oxide-based composite films: from the effects of doping to phase on photoactivity and gas sensing properties. J App Phys 120:135306–135309View ArticleGoogle Scholar
- Zha R, Nadimicherla R, Guo X (2015) Ultraviolet photocatalytic degradation of methyl orange by nanostructured TiO2/ZnO heterojunctions. J Mater Chem A 3:6565–6574View ArticleGoogle Scholar
- Miao Y, Zhang HJ, Yuan S, Jiao Z, Zhu XD (2016) Preparation of flower-like ZnO architectures assembled with nanosheets for enhanced photocatalytic activity. J Colloid Interface Sci 462:9–18View ArticleGoogle Scholar
- Zhang Y, Xing ZP, Liu XF, Li ZZ, Wu XY, Jiang JJ, Li M, Zhu Q, Zhou W (2016) Ti3+ self-doped blue TiO2(B) single-crystalline nanorods for efficient solar-drive photocatalytic performance. ACS Appl Mater Interfaces 8:26851–26859View ArticleGoogle Scholar
- Zhang N, Xie SJ, Weng B, Xu YJ (2016) Vertically aligned ZnO-au@CdS core-shell nanorod arrays as an all-solid-state vectorial Z-scheme system for photocatalytic application. J Mater Chem A 4:18804–18814View ArticleGoogle Scholar
- Fang SM, Xin YJ, Ge L, Han CC, Qiu P, Wu LN (2015) Facile synthesis of CeO2 hollow structures with controllable morphology by template-engaged etching of Cu2O and their visible light photocatalytic performance. Appl Catal B-Environ 179:458–467View ArticleGoogle Scholar
- Mukhopadhyay S, Maiti D, Chatterjee S, Devi PS, Kumar GS (2016) Design and application of au decorated ZnO/TiO2 as a stable photocatalyst for wide spectral coverage. Phys Chem Chem Phys 18:31622–31633View ArticleGoogle Scholar
- Liang YC, Lung TW (2016) Growth of hydrothermally derived CdS-based nanostructures with various crystal features and Photoactivated properties. Nanoscale Res Lett 11:264View ArticleGoogle Scholar
- Wu Y, Xu F, Guo DF, Gao ZY, Wu DP, Jiang K (2013) Synthesis of ZnO/CdSe hierarchical heterostructure with improved visible photocatalytic efficiency. Appl Surf Sci 274:39–44View ArticleGoogle Scholar
- Zou XW, Fan HQ, Tian YM, Yan SJ (2014) Synthesis of Cu2O/ZnO hetero-nanorod arrays with enhanced visible light-driven photocatalytic activity. CrystEngComm 16:1149–1156View ArticleGoogle Scholar
- Chen DM, Wang KW, Xiang DG, Zong RL, Yao WQ, Zhu YF (2014) Significantly enhancement of photocatalytic performances via core-shell structure of ZnO@mpg-C3N4. Appl Catal B-Environ 147:554–561View ArticleGoogle Scholar
- Liang YC, Liu SL, Hsia HY (2015) Physical synthesis methodology and enhanced gas sensing and photoelectrochemical performance of 1D serrated zinc oxide–zinc ferrite nanocomposites. Nanoscale Res Lett 10:350View ArticleGoogle Scholar
- Dong C, Wu KL, Li MR, Liu L, Wei XW (2014) Synthesis of Ag3PO4-ZnO nanorod composites with high visible-light photocatalytic activity. Catal Commun 46:32–35View ArticleGoogle Scholar
- Yang YW, Que WX, Zhang XY, Xing YL, Yin XT, Du YP (2016) Facile synthesis of ZnO/CuInS2 nanorod arrays for photocatalytic pollutants degradation. J Hazard Mater 317:430–439View ArticleGoogle Scholar
- Song JM, Zhang J, Ni JJ, Niu HL, Mao CJ, Zhang SY, Shen YH (2014) One-pot synthesis of ZnO decorated with AgBr nanoparticles and its enhanced photocatalytic properties. CrystEngComm 16:2652–2659View ArticleGoogle Scholar
- Peng FP, Ni YR, Zhou Q, Kou JH, Lu CH, Xu ZZ (2017) Construction of ZnO nanosheet arrays within BiVO4 particles on a conductive magnetically driven cilia film with enhanced visible photocatalytic activity. J Alloy Compd 690:953–960View ArticleGoogle Scholar
- Liang YC, Lin TY, Lee CM (2015) Crystal growth and shell layer crystal feature-dependent sensing and photoactivity performance of zinc oxide–indium oxide core-shell nanorod heterostructures. CrystEngComm 17:7948–7955View ArticleGoogle Scholar
- Liang YC, Lung TW, Xu NC (2017) Photoexcited properties of tin Sulfide Nanosheet-decorated ZnO Nanorod Heterostructures. Nanoscale Res Lett 12:258View ArticleGoogle Scholar
- Lin ZJ, Zhu Q, Dong Y, Liu SH, Li JG, Li XD, Huo D, Zhang M, Xie M, Sun XD (2016) Synthesis and formation mechanisms of morphology-controllable indium-containing precursors and optical properties of the derived In2O3 particles. CrystEngComm 18:3768–3776View ArticleGoogle Scholar
- Espid E, Taghipour F (2017) Development of highly sensitive ZnO/In2O3 composite gas sensor activated by UV-LED. Sens Actuators B Chem 241:828–839View ArticleGoogle Scholar
- Wei HZ, Cui XZ, Wang X, Xie ML, Wang LQ, Zhang J (2017) Tian, hierarchical assembly of In2O3 nanoparticles on ZnO hollow nanotubes using carbon fibers as templates: enhanced photocatalytic and gas-sensing properties. J Colloid Interface Sci 498:263–270View ArticleGoogle Scholar
- Martha S, Reddy KH, Parida KM (2014) Fabrication of In2O3 modified ZnO for enhancing stability, optical behaviour, electronic properties and photocatalytic activity for hydrogen production under visible light. J Mater Chem A 2:3621–3631View ArticleGoogle Scholar
- Zhang F, Li XY, Zhao QD, Chen AC (2016) Facile and controllable modification of 3D In2O3 microflowers with In2S3 nanoflakes for efficient photocatalytic degradation of gaseous ortho-dichlorobenzene. J Phys Chem C 120:19113–19123View ArticleGoogle Scholar
- Xing YL, Que WX, Yin XT, He ZL, Liu XB, Yang YW, Shao JY, Kong LB (2016) In2O3/Bi2Sn2O7 heterostructured nanoparticles with enhanced photocatalytic activity. Appl Surf Sci 387:36–44View ArticleGoogle Scholar
- Mady AH, Baynosa ML, Tuma D, Shim JJ (2017) Facile microwave-assisted green synthesis of Ag-ZnFe2O4@rGO nanocomposites for efficient removal of organic dyes under UV- and visible-light irradiation. Appl Catal B-Environ 203:416–427View ArticleGoogle Scholar
- She P, Xu KL, He QR, Zeng S, Sun H, Liu ZN (2017) Controlled preparation and visible light photocatalytic activities of corn cob-like au-ZnO nanorods. J Mater Sci 52:3478–3489View ArticleGoogle Scholar
- Thangavel S, Thangavel S, Raghavan N, Krishnamoorthy K, Venugopal G (2016) Visible-light driven photocatalytic degradation of methylene-violet by rGO/Fe3O4/ZnO ternary nanohybrid structures. J Alloy Compd 665:107–112View ArticleGoogle Scholar
- Hong YZ, Jiang YH, Li CS, Fan WQ, Yan X, Yan M, Shi WD (2016) In-situ synthesis of direct solid-state Z-scheme V2O5/g-C3N4 heterojunctions with enhanced visible light efficiency in photocatalytic degradation of pollutants. Appl Catal B-Environ 180:663–673View ArticleGoogle Scholar
- Wang J, Xia Y, Dong Y, Chen RS, Xiang L, Komarneni S (2016) Defect-rich ZnO nanosheets of high surface area as an efficient visible-light photocatalyst. Appl Catal B-Environ 192:8–16View ArticleGoogle Scholar
- Christoforidisa KC, Montini T, Bontempi E, Zafeiratosc S, Jaénd JJD, Fornasieroa P (2016) Synthesis and photocatalytic application of visible-light active β-Fe2O3/g-C3N4 hybrid nanocomposites. Appl Catal B-Environ 187:171–180View ArticleGoogle Scholar
- Liu HR, Hu YC, He X, Jia HS, Liu XG, Xu BS (2015) In-situ anion exchange fabrication of porous ZnO/ZnSe heterostructural microspheres with enhanced visible light photocatalytic activity. J Alloy Compd 650:633–640View ArticleGoogle Scholar
- Jo WK, Natarajan TS (2015) Facile synthesis of novel redox-mediator-free direct Z-scheme CaIn2S4 marigold-flower-like/TiO2 photocatalysts with superior photocatalytic efficiency. ACS Appl Mater Interfaces 7:17138–17154View ArticleGoogle Scholar
- Tang H, Chang SF, Tang GG, Liang W (2017) AgBr and g-C3N4 CO-modified Ag2CO3 photocatalyst: a novel multi-heterostructured photocatalyst with enhanced photocatalytic activity. Appl Surf Sci 391:440–448View ArticleGoogle Scholar
- Zhou M, Yang H, Xian T, Li RS, Zhang HM, Wang XX (2015) Sonocatalytic degradation of RhB over LuFeO3 particles under ultrasonic irradiation. J Hazard Mater 289:149–157View ArticleGoogle Scholar
- Chen XX, Li R, Pan XY, Huang XT, Yi ZG (2017) Fabrication of In2O3-Ag-Ag3PO4 composites with Z-scheme configuration for photocatalytic ethylene degradation under visible light irradiation. Chem Eng J 320:644–652View ArticleGoogle Scholar
- Islam MJ, Reddy DA, Han NS, Choi J, Song JK, Kim TK (2016) An oxygen-vacancy rich 3D novel hierarchical MoS2/BiOI/AgI ternary nanocomposite: enhanced photocatalytic activity through photogenerated electron shuttling in a Z-scheme manner. Phys Chem Chem Phys 18:24984–24993View ArticleGoogle Scholar
- Siol S, Hellmann JC, Tilley SD, Graetzel M, Morasch J, Deuermeier J, Jaegermann W, Klein A (2016) Band alignment engineering at Cu2O/ZnO Heterointerfaces. ACS Appl Mater Interfaces 8:21824–21831View ArticleGoogle Scholar
- Ma LT, Fan HQ, Tian HL, Fang JW, Qian XZ (2016) The n-ZnO/n-In2O3 heterojunction formed by a surface-modification and their potential barrier-control in methanal gas sensing. Sens Actuators B: Chem 222:508–516View ArticleGoogle Scholar
- Xu R, Li HH, Zhang WW, Yang ZP, Liu GW, Xu ZW, Shao HC, Qiao GJ (2016) The fabrication of In2O3/In2S3/Ag nanocubes for efficient photoelectrochemical water splitting. Phys Chem Chem Phys 18:2710–2717View ArticleGoogle Scholar