TiO2 Nanosheets on Flexible Ti Mesh for

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Cite This: Inorg. Chem. XXXX, XXX, XXX−XXX

In Situ Synthesis of Pt/TiO2 Nanosheets on Flexible Ti Mesh for Efficient and Cyclic Phenol Removal Zheng Zhang,† Xuelei Li,‡ Ruishi Zhang,*,‡ Zhumin Zhang,§ and Jianglong Yu*,†,∥ †

Key Laboratory of Advanced Coal and Coking Technology of Liaoning Province, School of Chemical Engineering, University of Science and Technology Liaoning, Anshan,114051, China ‡ Department of Chemistry and Material Engineering, Yingkou Institute of Technology, Bowen Road, Yingkou, 115014 China § Dalian Xinheng Environmental Protection Technology Co., LTD, Dalian, 116620, China ∥ Chemical Engineering, University of Newcastle, Callaghan, NSW 2308, Australia Inorg. Chem. Downloaded from pubs.acs.org by BETHEL UNIV on 05/17/19. For personal use only.

S Supporting Information *

ABSTRACT: TiO2 nanostructures that feature a two-dimensional (2D) morphology have attracted extensive attention in environment processing and energy conversion fields owing to their peculiarly large surface area and superior transfer efficiency of photogenerated carriers. In this work, we proposed a hybrid approach including a plasma electrolyte oxidation (PEO) and ion exchange strategy to in situ synthesize TiO2 nanosheets on a flexible Ti mesh substrate, in which the layered Na2Ti2O5 nanosheets were fabricated as a template. The TiO2 nanosheets are crystalline anatase phase and exhibit excellent photocatalytic activity and stability in removing phenol. With the modification of the Pt cocatalyst, the phenol degradation performance has been significantly enhanced. More importantly, the in situ grown TiO2 nanosheets on the flexible Ti mesh provide strong substrate adhesion that enables superior photocatalytic stability for cyclic degradation of phenol. It can be expected that the synthetic strategy proposed in this work can pave a solid way toward the in situ growth of various TiO2-based composite nanophotocatalysts with sufficient active sites and excellent photocatalytic properties, and thus, it will open up more opportunities for environment processing and energy conversion.

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INTRODUCTION As one of the most promising photocatalysts, TiO2 has been widely used in the fields of photodegradation,1,2 water splitting,3−6 and CO2 reduction7 due to its nontoxicity, excellent chemical stability, and superior photocatalytic activity. In the photocatalytic process, the light absorption and the separation and transfer of photogenerated carriers are the key fundamental factors that closely affect the quantum efficiency and solar conversion efficiency.8,9 To date, extensive research efforts have been devoted to optimize the aforementioned issues on the basis of nanostructure design,9 doping,10 facet engineering,11−14 heterostructure,15−17 and cocatalyst modification.18 However, the loading problem of TiO2 nanostructures on the supporter aimed to obtain superior substrate adherence for stable and cyclic photocatalytic performance has always been overlooked. In fact, the powder-form TiO2 catalysts are generally required to load on the supporter or press into porous ceramics to avoid the secondary pollution and the loss of mass and activity in practical industry application. Additionally, it is also of great importance to balance the catalytic activity and stability in consideration of the loading adhesion. In this case, an in situ synthesis strategy that can meet these requirements is thus © XXXX American Chemical Society

expected. Previous work has demonstrated the feasibility and possibility of hydrothermal reaction in realizing the in situ synthesis of diverse TiO2 nanostructures on different substrates.19,20 However, the adhesion between TiO2 and the substrate is still too weak and fragile for the impact of an external influence like water and gas flow, which greatly affects its catalytic stability. Therefore, searching for an effective approach to further optimize the substrate adhesion of TiO2 photocatalysts with a large surface areas is still urgent and desirable. Plasma electrolytic oxidation (PEO) as a popular and effective surface modification technology can create the TiO2 ceramic layers on Ti metal with strong mechanical contact.21,22 On the other hand, hydrothermal reaction can directly convert TiO2 particles/film to diverse TiO2 nanostructures with a uniform morphology.9 Therefore, the combination and full utilization of advantageous PEO and hydrothermal methods can effectively address the aforementioned loading problems. The TiO2 film obtained by the PEO process can not only Received: February 13, 2019

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DOI: 10.1021/acs.inorgchem.9b00440 Inorg. Chem. XXXX, XXX, XXX−XXX

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Inorganic Chemistry

Figure 1. SEM images of (a, d) PEO film, (b, e) sodium titanate nanosheets, and (c, f) TiO2 nanosheets.

catalytic activity in removing organic pollutants. To further improve the photocatalytic performance, noble metals were considered as suitable cocatalysts to form surface junctions to promote the separation and transfer efficiency of photogenerated electrons and holes. Due to its large work function, high activity, possible hot electron injection, and enhanced UV light absorption induced by localized surface plasmon resonance (LSPR),30 Pt metal was chosen to photodeposit on the surface of TiO2 nanosheets. It was found that the overall photocatalytic activity could be greatly enhanced. More importantly, our synthetic strategy proposed in this work has effectively addressed the loading problem of the TiO2 nanocatalyst without sacrificing the catalytic activity.

guarantee excellent substrate adhesion but also provide Ti precursor for the in situ growth of TiO2 nanostructures. Additionally, two-dimensional (2D) structures with a thin layer thickness can endow photocatalysts with higher separation efficiency of photogenerated carriers and large active areas for cocatalyst modification,23−25 so it is very meaningful and crucial to synthesize ultrathin TiO2 nanosheets for achieving higher catalytic performance. Unfortunately, the anatase TiO2 nanosheet with dominant exposed {001} facets was usually prepared by the hydrothermal reaction in the presence of HF.12,13 The shape-control agents of hydrogen fluoride are highly corrosive and dangerous, and the obtained TiO2 nanosheets were always mixed with some particles and inevitably contaminated with fluorinion on the surface. Note that titanate has a typical layered structure and thus easily forms the nanosheet morphology with an ultrathin thickness of several nanometers.26−28 Therefore, employing a layered titanate template to prepare TiO2 nanosheets would be more efficient to realize the above target and simultaneously control their thickness and morphology. In fact, Gao et al.29 have demonstrated the synthetic possibility and mechanism of titanate to TiO2 nanotubes. They first prepared sodium titanate by hydrothermal reaction with NaOH and rutile TiO2 particles, then exchanged sodium ions with protons in dilute HCl, and finally calcined the sample at a certain temperature to dehydrate. In the same way, Chen et al.24 have also successfully obtained TiO2 nanosheets with 3 monolayers by using P25 TiO2, which shows higher photocatalytic activity than P25 in the degradation of RhB. As a result, the in situ synthesis of TiO2 nanosheets on a Ti substrate via a titanate template is feasible and meaningful for the diverse industrial applications including photocatalysis and gas catalysis. In this work, we demonstrate the in situ synthesis of ultrathin TiO2 nanosheets on a flexible Ti mesh through a hybrid PEO and hydrothermal method, followed by a cation exchange and dehydration process. The utilization of the above technologies enables the TiO2 nanosheets with strong substrate adhesion, huge surface areas, and excellent photo-

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RESULTS AND DISCUSSION The in situ synthesis strategy of TiO2 nanosheets was designed by combining PEO and hydrothermal methods, followed by a cation exchange and dehydration process. To promote the industrial application, a flexible Ti mesh with a uniform pore size of 2 × 1 mm was chosen as substrate. It can be seen from Figure 1a,b that the morphology of PEO film was mainly composed of the typical volcanic appearance arising from the micro-arc discharge of the Ti anode under high voltage in electrolyte, as observed in previous work.20,31,32 Beneath the porous structure, there still exists dense PEO film with strong adherence to the Ti substrate. XRD analysis demonstrates that the obtained PEO film crystallizes in anatase TiO2 phase (Figure S1). To achieve nanostructures with a uniform morphology and large surface area, hydrothermal reaction was then used to further deal with this TiO2 PEO film under NaOH solution. In comparison with the initial porous PEO film, the hydrothermal sample was uniformly covered with a dense layer of nanosheets with an average length and width up to 5 and 0.5 μm, as shown in Figure 1c,d. According to the EDS analysis in Figure S2, the nanosheets are only composed of Na, Ti, and O elements. It also indicates that the TiO2 film obtained by PEO has been converted into sodium titanate nanosheets after the hydrothermal process. B

DOI: 10.1021/acs.inorgchem.9b00440 Inorg. Chem. XXXX, XXX, XXX−XXX

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To get further insight into the microstructure of TiO2 nanosheets, TEM analysis was conducted. As illustrated in Figure 3a, TiO2 nanosheets possess a thin thickness and show

As is well-known, sodium titanate is an excellent host material for cation exchange owing to the layered structure.26,29 For the purpose of preparing pure TiO2 nanosheets from the titanate template, a proton is first used to replace sodium ions in the layered structure of sodium titanate. In this case, sodium titanate can be completely transformed into titanic acid. To finally achieve TiO2 nanosheets from titanic acid, a heat-treatment process under 500 °C for 2 h was carried out to remove the molecular H2O. Figure 1e,f displays that the heat-treated sample still maintains a similar morphology with as-prepared sodium titanate nanosheets except for the rolling up of edges caused by dehydration. The corresponding X-ray diffraction patterns (Figure 2) also verify the formation of

Figure 3. (a) Bright field TEM and (b, c) HRTEM images of TiO2 nanosheets, and (d) the corresponding FFT pattern of (c). Figure 2. XRD patterns of sodium titanate, titanic acid, and TiO2 nanosheets.

no damage and collapse of the framework and morphology during the phase conversion from Na2Ti2O5 to TiO2,33 but the high resolution TEM image (HRTEM, Figure 3b) demonstrates that the obtained TiO2 nanosheets are polycrystalline. This means that there exists renucleation and recrystallization breaking the periodicity of the lattice in the process of cation exchange and heat-treatment. The measured interplanar distance of 0.35 nm approaches well with the d-spacing of the (101) plane of anatase TiO 2 (Figure 3c). The corresponding fast Fourier transformation (FFT) in Figure 3d also shows the similar diffraction patterns of the [010] zone axis with that of anatase TiO2, in consistence with XRD results. Therefore, TiO2 nanosheets prepared from the template of single crystalline Na2Ti2O5 are polycrystalline and belong to the tetragonal anatase structure. Figure 4 shows the UV− visible reflectance spectra of Na2Ti2O5 and TiO2. It can be observed that their absorption edge reaches to 340 and 390 nm, respectively. According to the Figure S5, the band gaps of Na2Ti2O5 and TiO2 are calculated to be 3.6 and 3.2 eV, matching well with the corresponding theoretical values.34,35 TiO2 as a well-known photocatalyst has been used for removing organic pollutants to address the present environmental problems.1 To efficiently evaluate the activity of assynthesized TiO2 nanosheets on Ti mesh, the photocatalytic degradation of phenol, a typical toxic intermediate of aromatic hydrocarbons, was carried out. For the purpose of improving the overall photocatalytic activity, a noble Pt cocatalyst was used to enhance the surface separation and transfer efficiency of photogenerated electrons and holes.18 Figure 5 displays the TEM analysis of TiO2 nanosheets with 5 mg of Pt modification. As observed in Figure 5a, Pt nanoparticles with a size of about 1−5 nm are successfully decorated on the rough surface of TiO2 nanosheets through the photodeposition

sodium titanate27 nanosheets via hydrothermal reaction and the synthesis of H2Ti2O5·H2O after the ion exchange process in dilute HCl. As the radius of a proton is smaller than that of a sodium ion, the diffraction peaks of the obtained titanic acid nanosheets obviously shift to the large angle direction in comparison with sodium titanate. Additionally, all peaks have a larger full width at half-maximum (fwhm) than those of sodium titanate, indicating the break of the periodic lattice in the process of proton exchange. Note that all XRD peaks of sodium titanate have a good match with those of H2Ti2O5· H2O except for some shifts to a small angle. Therefore, the chemical formula of sodium titanate is speculated to be Na2Ti2O5. In fact, EDS composition analysis and calculation of a single nanosheet under TEM mode also prove the above conclusion (Table S1). After calcination at 500 °C, the diffraction peaks indexed to H2Ti2O5·H2O disappear, while those peaks belonging to anatase TiO2 become dominant, indicating the phase transition from H2Ti2O5·H2O to anatase TiO2, as shown in Figure 2. In a word, anatase TiO2 nanosheets were successfully prepared on Ti mesh through our designed synthesis strategy. The low magnification SEM images in Figure S3 reveal the superior uniformity of TiO2 nanosheets prepared by this method. According to the crosssectional SEM image in Figure S4, it can be found that TiO2 nanosheets were firmly grown on the PEO film without any gaps and cracks. The thicknesses of TiO2 nanosheets and PEO film are about 10 and 10 μm, respectively. Since the PEO film has strong mechanical contact with the Ti substrate, it can be thus concluded that the loading problem of TiO2 nanosheets can be effectively solved through our synthetic strategy. C

DOI: 10.1021/acs.inorgchem.9b00440 Inorg. Chem. XXXX, XXX, XXX−XXX

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particle size of the Pt cocatalyst dramatically increases from 1− 5 nm to 10−20 nm as shown in Figure S7, and the distribution of particle size and shape becomes nonuniform. It should be noted that the coverage of Pt particles on the TiO2 nanosheet is moderate on the basis of the photodeposition method, which effectively reserves the active sites of TiO2 photocatalysts on the balance of the high decoration content of Pt nanoparticles. The phenol degradation performance of the TiO2 nanosheet with/without Pt cocatalyst modification is shown in Figure 6. In the absence of the TiO2 nanosheet photocatalyst, there is nearly no degradation occurring for the phenol solution under the intense light irradiation (500 mW cm−2), revealing the extreme stability and refractory of the phenol pollutant. To exclude the influence of adsorption on the real photocatalytic activity, a 30 min adsorption and desorption balance was carried out under dark conditions before the measurements. With adding the TiO2 nanosheet photocatalyst, all phenol pollutants (10 mg/L) could be almost removed in 180 min under the same light irradiation, exhibiting the excellent photocatalytic activity of the TiO2 nanosheet. The possible reason is that the thin thickness of TiO2 nanosheets effectively reduces the transfer distance and recombination efficiency of photogenerated carriers. Additionally, the obtained TiO2 nanosheets belong to the anatase structure which possesses the best photocatalytic performance compared with rutile and brookite. Thus, despite the polycrystalline nature, they still show excellent photocatalytic activity. To further improve the overall photocatalytic performance, the Pt cocatalyst was decorated on the surface of the nanosheet to promote the separation and transfer of photogenerated electrons and holes. It can be observed that Pt cocatalyst modification directly leads to the obvious enhancement of photocatalytic activity (Figure 6a). For the sample of TiO2 nanosheet with 5 mg of Pt, the phenol degradation ratio can be up to 87% under 150 min. When the amount of Pt content is increased to 10 mg, the phenol degradation ratio can reach to 92% with only a time demand of 120 min. When the decorated Pt content finally

Figure 4. UV−visible reflectance spectra of sodium titanate, and TiO2 nanosheets with different concentrations of Pt cocatalysts.

method.36 The HRTEM image of a Pt particle in Figure 5b proves that Pt cocatalysts exist in the form of a metal state with a face centered cubic (fcc) structure. The measured distance of 0.226 nm between the adjacent lattice fringes is in good accordance with the theoretical value of the (111) plane. According to the composition contrast (Figure 5a) and elemental mapping in STEM mode (Figure 5c−f), it can be demonstrated that Pt cocatalysts are uniformly covered on the surface of the TiO2 nanosheet. To investigate the decorated amount of Pt on the photocatalytic performance enhancement, a series of amounts of 5, 10, and 15 mg of Pt modification in nominal content were carried out, as shown in Figures S6 and S7. From the optical photographs in Figure S6, it can be seen that the color of the Ti mesh with TiO2 nanosheets gradually changes from white to dark as the Pt content increases. In fact, the absorption spectra in Figure 4 also demonstrate the increased absorption of visible light, which may mainly come from the low refection effect of Pt nanoparticles. In addition to the increase of light absorption, it could be also found that the

Figure 5. (a) TEM, (b) HRTEM, and (c) STEM images of TiO2 nanosheets with 5 mg of Pt modification. (d−f) Corresponding elemental mapping. D

DOI: 10.1021/acs.inorgchem.9b00440 Inorg. Chem. XXXX, XXX, XXX−XXX

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Figure 6. (a) Photocatalytic degradation of phenol of TiO2 nanosheets and Pt/TiO2. (b) Corresponding apparent rate constants of phenol degradation.

reaches to 15 mg, the degradation ratio of 90% within 90 min can be achieved. In comparison with other TiO2 nanosheet photocatalysts, Pt/TiO2 nanosheets obtained in this work exhibit excellent photodegradation efficiency (Table S2). The possible reason for the increase of photocatalytic activity can be ascribed to the improved separation and transfer efficiency of photogenerated carriers and the enhanced light absorption after Pt cocatalyst modification, as shown in Figure 4. However, the particle size of the Pt cocatalyst is closely related to the photocatalytic activity and there exists an optimum value.37 Decreasing the particle size of the Pt cocatalyst is helpful to improve the active sites and corresponding photocatalytic activity of TiO2. But, when the size of Pt is smaller than 5 nm, its adsorption capability would become very strong, which, in turn, prevents the desorption of intermediate products and thus decreases the overall activity. Therefore, the sample of TiO2 nanosheet with 5 mg of Pt exhibits the lowest activity in comparison with other samples due to its smaller size of 3−5 nm. It should be noted that a continuous increase of Pt content facilitates the improvement in the overall photocatalytic performance, but also easily causes the sharp increase and unevenly distribution of Pt particle size which may decrease the effective utilization rate of the Pt cocatalyst. Figure 6b reveals the apparent rate constants of phenol degradation reaction for TiO2 nanosheets with/without Pt cocatalyst. The obtained curves comparatively fit well with the first order of Langmuir−Hinshelwood kinetics.38 It demonstrates that the degradation reaction is mainly controlled by the two factors of adsorption and reaction processes. According to the fitting curves in Figure 6b, the apparent rate constants are calculated to be 0.0095, 0.0138, 0.0173, and 0.0210 min−1 for TiO2, TiO2/5 mg Pt, TiO2/10 mg Pt, and TiO2/15 mg Pt. Additionally, it can be found that the last points easily deviate from the fitting curves in Figure 6b. It is mainly due to the extremely low concentration of phenol in the last stage of the degradation process. In this case, the adsorption process dominates the rate-determining step of photocatalysis in comparison with the reaction process. The property stability of a photocatalyst has always been considered to be another important factor in the practical application. Figure 7 shows the recycling stability of TiO2 nanosheets with 15 mg of Pt modification toward phenol removal. It can be seen that, over five continuous cycles, there is a little deviation of the photocatalytic performance owing to the peeling of Pt particles. It effectively demonstrates the excellent stability and sustainability of TiO2 nanosheets firmly grown on the Ti mesh. The photodegradation mechanism of

Figure 7. Recycling stability of TiO2 nanosheets with 15 mg of Pt modification toward phenol removal.

the TiO2 nanosheet is the same as that reported in the literatures.1,39 The photogenerated electrons and holes in the conduction/valence band of the TiO2 nanosheet migrate from the inside to the surface and then react with the adsorbed species (e.g., O2, OH−) to generate the reactive oxygen species of ·OH which can directly decompose phenol to micromolecules and the final CO2 and H2O. The previous work has demonstrated that TiO2 photocalysts can degrade the phenol and RhB pollutants into CO2 by TOC (total organic carbon)40 and COD (chemical oxygen demand)41 analysis. With the modification of the Pt cocatalyst, the electrons may easily transfer from the surface to the Pt particle and react with the adsorbed species (e.g., O2, OH−) to generate the reactive oxygen species of ·OH. Undoubtedly, the sufficient active sites and the improved efficiency of carrier separation of the Pt/ TiO2 nanosheet photocatalyst, as well as the superior mechanical adherence of TiO2 nanosheets in situ grown on Ti mesh, jointly contribute to the excellent photocatalytic property and cyclic performance. Therefore, it is expected that the synthesis strategy proposed in this work can be applied to the in situ growth of a variety of semiconductor photocatalysts for diverse applications including water-splitting, photodegradation of organic pollutants, etc.

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CONCLUSION In summary, we demonstrated an in situ synthesis strategy including PEO, hydrothermal reaction, and cation exchange toward the fabrication of TiO2 nanosheets with huge surface areas and strong mechanical substrate adherence. This E

DOI: 10.1021/acs.inorgchem.9b00440 Inorg. Chem. XXXX, XXX, XXX−XXX

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for 30 min to attain a balance between adsorption and desorption for the catalyst and phenol. The photocatalytic process was carried out under xenon lamp irradiation with a light density of 500 mW/cm2 and a 1.5 M filter without any stirring. The wavelength range of irradiation light is from 300 to 1100 nm. The reactor is maintained at room temperature using a simple circulating water cooling system. At given time intervals, 2.5 mL of solution was collected and analyzed by a UV−vis spectrophotometer (Hitachi U-3900) to record the maximum absorption peak (269 nm for phenol) and confirm the photodegradation efficiency.

approach effectively solves the loading problem of a TiO2 catalyst on the basis of balancing the catalytic activity and stability. The TiO2 nanosheets converted from the template via a cation exchange process maintain well the initial morphology and framework of sodium titanate nanosheets. Importantly, the superior mechanical adherence of these nanosheets is well reserved for achieving advantageous cyclicity during the photocatalytic process. TEM analysis reveals that the obtained TiO2 nanosheets are polycrystalline and crystallized in the anatase structure. Photocatalytic test reveals that the TiO2 nanosheets exhibit excellent performance in removing phenol, and an enhanced photodegradation capability after Pt cocatalyst modification, owing to the increase of separation and transfer efficiency of photogenerated carriers and light absorption. It is expected that this work will provide a new perspective and strategy in the design of the complex TiO2 based nanocatalysts with strong mechanical contact for various applications including gas catalysis and energy conversion and storage.

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ASSOCIATED CONTENT

* Supporting Information S

The Supporting Information is available free of charge on the ACS Publications website at DOI: 10.1021/acs.inorgchem.9b00440.

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EXPERIMENTAL SECTION

Preparation of TiO2 Nanosheets. The in situ synthesis of TiO2 nanosheets on the flexible Ti mesh was obtained through PEO and hydrothermal methods, followed by a cation exchange and dehydration process. First, Ti mesh was cut with a size of 50 mm × 50 mm and was cleaned with acetone, ethanol, and distilled water to remove the surface contamination. In the PEO process,21,31,42 two graphite plates, Ti mesh, and Na3PO4 (10 g/L) were used as cathodes, anode, and electrolyte, respectively. The current, frequency, and duty cycle of PEO parameters were fixed at 100 mA/cm2, 1000 Hz, and 0.6. The overall time of the plasma discharge process lasted for 4 min at a constant temperature of 20 °C. After that, the TiO2 PEO film was rinsed in distilled water and then transferred into a 25 mL Teflon-lined stainless-steel autoclave with 15 mL of 4 M NaOH solution. The hydrothermal reaction was maintained at 200 °C for 24 h. The obtained sodium titanate nanosheets on Ti mesh were impregnated in 1 M HCl solution for 24 h. In this process, the sodium ions were completely exchanged by protons. Finally, TiO2 nanosheets with uniform morphology were prepared by a following calcination process at 500 °C for 2 h to dehydrate titanic acid. Photodeposition of Pt Cocatalyst. The Pt cocatalyst nanoparticles were deposited on the surface of TiO2 nanosheets by a photoreduction method. Briefly, 50 mm × 50 mm Ti mesh with in situ grown TiO2 nanosheets was put into a breaker containing a 50 mL of H2PtCl6·6H2O and 5 mL of methanol solution under the irradiation of a xenon lamp (500 mW/cm2) for 2 h. The size and density of Pt nanoparticles were controlled by changing the concentration of H2PtCl6·6H2O from 0.1 to 0.2 and 0.3 mg/mL. Finally, these obtained Pt/TiO2 nanosheets were rinsed with deionized water and then dried at 70 °C in a drying oven for 8 h. Characterizations. The morphology, composition, and microstructure of as-prepared samples were characterized by a fieldemission scanning electron microscopy (SU-70 SEM) equipped with an Oxford Max energy-dispersive X-ray spectrometer (EDS) system, and a 200 kV transmission electron microscopy (TEM, FEI, Tecnai G2 F20). The crystal structure and phase of all samples were analyzed by X-ray diffraction (XRD, Rigaku D/max 2400) with Cu Kα radiation as the X-ray source (λ = 0.154056 nm). UV−vis diffuse reflectance spectra (DRS) of TiO2 and Pt/TiO2 were obtained through a HITACHI U-3900 spectrophotometer with an integrating sphere using BaSO4 as the reference. Photocatalytic Performance Measurements. The photocatalytic performance of TiO2 and Pt/TiO2 nanosheets was mainly evaluated using the photodegradation of phenol as a probe reaction. Two Ti meshes (50 mm × 50 mm) with in situ grown TiO2 nanosheets were put into 50 mL of a solution containing 10 mg/L phenol. Then the TiO2 nanosheets are transferred to dark conditions

XRD pattern of PEO film; EDS results, SEM images, TEM images, and UV−vis spectra of PEO film, sodium titanate, and TiO2 nanosheet; optical photographs of Pt/ TiO2 nanosheets (PDF)

AUTHOR INFORMATION

Corresponding Authors

*E-mail: [email protected] (R.Z.). *E-mail: [email protected] (J.Y.). ORCID

Ruishi Zhang: 0000-0002-0606-1635 Notes

The authors declare no competing financial interest.

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ACKNOWLEDGMENTS This work was partially supported by the National Natural Science Foundation of China (21607068) and the Education Department Funding Program of Liaoning Province (2016HZPY06). The funding from the Youth Foundation of University of Science and Technology Liaoning (2016QN27) is also acknowledged.

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REFERENCES

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DOI: 10.1021/acs.inorgchem.9b00440 Inorg. Chem. XXXX, XXX, XXX−XXX

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DOI: 10.1021/acs.inorgchem.9b00440 Inorg. Chem. XXXX, XXX, XXX−XXX