Microsoft Word - 04 CAN-1409-layout Characterization and Application of Nanomaterials (2022) Volume 5 Issue 1 doi:10.24294/can.v5i1.1409 19  Original Research Article Preparation of PbTiO3-CdS nanocomposite material and its micro- structure and photocatalytic properties Mingdong Xu, Wenqiang Li, Shun Liu, Tao Zhang, Sen Lai, Simin Yin* Faculty of Mechanical Engineering & Automation, Zhejiang Sci-Tech University, Hangzhou 310018, Zhejiang, China. E-mail: yinsm@zstu.edu.cn ABSTRACT In order to explore the influence of the ferroelectric surface on the structure and properties of semiconductor ox- ides, the growth of CdS nanocrystals was regulated and controlled by taking single-crystal perovskite PbTiO3 nanosheets as the substrate through a simple hydrothermal method. Through composition design, a series of PbTiO3-CdS nanocomposite materials with different loading concentrations were prepared, and their microstructure and photocatalytic properties were systematically analyzed. Studies show that in the prepared product, CdS nanoparticles selectively grow on the surfaces of PbTiO3 nanosheets, and their morphology is affected by the exposed surfaces of PbTiO3 nanosheets. There is a clear interface between the PbTiO3 substrate and CdS nanoparticles. The concentration of the initial reactant and the time of hydrothermal reaction also significantly affect the crystal morphology of CdS. Pho- tocatalysis studies have shown that the prepared PbTiO3-CdS nanocomposite material has a significant degradation ef- fect on 10 mg/L of Rhodamine B aqueous solution. The degradation efficiency rises with the increase of CdS loading concentration. When degrading 10 mg/L of Rhodamine B aqueous solution, the PbTiO3-CdS sample with a mass frac- tion of 3% can reach a degradation rate of 72% within 120 min. Keywords: CdS; Single-Crystal Perovskite; PbTiO3; Nanocomposite Material; Photocatalysis ARTICLE INFO Received: 8 October 2021 Accepted: 17 December 2021 Available online: 23 December 2021 COPYRIGHT Copyright © 2022 Mingdong Xu, et al. EnPress Publisher LLC. This work is li- censed under the Creative Commons Attribu- tion-NonCommercial 4.0 International Li- cense (CC BY-NC 4.0). https://creativecommons.org/licenses/by-nc/4 .0/ 1. Introduction Nano materials have many characteristics, such as small size ef- fect, surface effect, volume effect and unique photoelectric effect, which make them have broad application prospects in energy envi- ronment, electronic devices, biomedicine and so on[1–3]. Perovskite phase PbTiO3 is a typical ferroelectric oxide material. It was report- ed by Shirane et al.[4] in 1950 that the PbTiO3 is with a Curie tempera- ture of about 480 ℃, and with high spontaneous polarization intensity, large dielectric constant and small dielectric loss. It is widely used in sensing, storage, infrared imaging and nano generator devices[5,6]. With the in-depth study of perovskite materials, researchers have made breakthroughs in the surface research of nanostructures of per- ovskite materials, and the research of the special surface ferroelectric polarization characteristics has gradually become an important direc- tion[7]. Using the composite-preparation technology and the ferroelec- tric polarization characteristics on the surface of perovskite nanostruc- tures can regulate the crystal growth of semiconductor oxides, so as to prepare new nanocomposite materials[8]. Previous studies have shown that nanocomposite materials have unique electron transport character- istics due to their special energy band structure and surface effects, so 20  they have become a research hotspot in the fields of solar cells, gas-phase catalysis, photocatalysis etc.[9] In 1972, Fujishima et al.[10] reported the re- search on the photolysis of water. In this research, TiO2 was used as a photoelectric electrode to de- compose water under visible light to prepare hy- drogen. Semiconductor[11] was used as an important research object of photocatalytic materials. Re- searchers have systematically studied other semi- conductor oxide systems, such as g-C3N4 [12,13], ZnO[14], MoS2 [15], and Fe2O3 [16]. Among many sem- iconductors, CdS[17] is a promising photocatalytic material because of its small band gap (Eg ≈ 2.4 eV) and good optical response in the visible band. However, due to its low electron-hole separation efficiency and electron mobility, CdS crystal mate- rials prepared by traditional methods are easy to agglomerate and form large particles, resulting in a significant reduction in their specific surface area, which seriously affects the photocatalytic efficiency of CdS. In view of the above problems, existing studies mainly promote the photocatalytic efficien- cy of CdS by loading precious metals, such as Pt[18], Ag[19], and Au[20], etc. However, due to the rarity of precious metals and the easy oxidation of CdS, the preparation cost of photocatalytic materials in- creases. In this paper, PbTiO3-CdS nanocomposite ma- terials were successfully synthesized by a secondary hydrothermal method with single-crystal perovskite phase PbTiO3 nanosheets as substrates and CdCl2·5/2H2O and CH4N2S as main reactants. Their microstructure and crystal growth were systemati- cally studied. The photocatalytic properties of the prepared PbTiO3-CdS nanocomposite materials were evaluated by the degradation efficiency of Rhodamine B aqueous solution under ultraviolet light and UV-Vis diffuse reflectance spectrum, which provided experimental material and theoreti- cal basis for the subsequent exploration of the syn- thesis and properties of more nanocomposite mate- rials. 2. Experiment 2.1 Experimental reagents Potassium hydroxide (KOH, analytical pure, Hangzhou Gaojing Chemical Co., Ltd.); Titanium dioxide (P25 TiO2, analytical pure, Shanghai Alad- din Biochemical Technology Co., Ltd.); Lead ni- trate (Pb(NO3)2, analytical pure, Shanghai Zhanyun Chemical Co., Ltd.); Cadmium chloride hemihy- drate (CdCl2·5/2H2O, analytical purity); Thiourea (CH4N2S, analytical purity) and Rhodamine B (C28H31CIN2O3, analytical purity) were provided by McLean Biochemical Technology Co., Ltd.; Abso- lute ethanol (C2H6O, analytical purity, Anhui Ante Food Co., Ltd.); Deionized water (H2O, self-made in the laboratory). 2.2 Synthesis of materials 2.2.1 Preparation of single-crystal perovskite phase PbTiO3 nanosheets Single-crystal perovskite phase PbTiO3 nanosheets were prepared by the method in the lit- erature[21]. 0.4 g of TiO2 powder was added to 6 mol/L of KOH aqueous solution to obtain a solution containing Ti4+ with the concentration of 0.1 mol/L. In the stirred state, 0.2 mol/L of Pb(NO3)2 aqueous solution was added to the Ti4+-contained solution to adjust the ratio of lead-titanium to 2:0 and stirred for 2 h. The obtained hydroxide solution of titanium and lead was transferred to the inner tank of a 50 mL stainless steel reactor, sealed, and then hydro- thermal reaction was carried out at 200 ℃ for 12 h. After the sample was cooled to room temperature, the sample was centrifuged and cleaned with de- ionized water and absolute ethanol respectively un- til the washing solution was neutral. Finally, the washed sample was dried at 60 ℃ for 24 h to obtain the PbTiO3 nanosheet sample to be tested. 2.2.2 Preparation of the PbTiO3-CdS nano- composite materials 0.2 g of prepared PbTiO3 nanosheets were dispersed in 30 mL of deionized water to obtain a white suspension. CdCl2·5/2H2O and CH4N2S were added to the above white suspension at a molar ra- tio of 1:1 to obtain a mixed solution, which was continuously stirred at room temperature for 30 min. Transfer the above mixed solution to the inner tank of a 50 mL stainless steel reactor, seal it, and then conduct hydrothermal reaction at 160 ℃ for 12 h. 21  After cooled to room temperature, the sample was centrifuged and cleaned with deionized water and absolute ethanol respectively until the washing so- lution was neutral. Finally, the washed sample was dried at 60 ℃ for 24 h to obtain the target product sample to be tested. 2.2.3 Preparation of CdS crystals (contrast samples) Using the above synthesis method, CdS crys- tals grown separately were prepared without adding PbTiO3 nanosheets. The specific synthesis process is as follows: add CdCl2·5/2H2O and CH4N2S with a molar ratio of 1:1 in 30 mL of deionized water, and obtain the precursor solution by magnetic stir- ring. After continuous stirring at room temperature for 30 min, transfer the above solution to the inner tank of a 50 mL stainless steel reactor for sealing, and conduct hydrothermal reaction at 160 ℃ for 12 h. After the reaction, cool the sample to room tem- perature, centrifuge and clean it with deionized wa- ter and absolute ethanol respectively until the eluent was neutral. Finally, the washed sample was dried at 60 ℃ for 24 h to obtain the contrast product sample to be tested. 2.3 Testing and characterization 2.3.1 Microscopic characterization of mate- rials The surface morphology of the material was characterized by a Zeiss ULTRA-55 scanning elec- tron microscope (SEM), and the acceleration volt- age was 5 kV. The powder sample was added to the resin with curing agents, stirred and cured by heating. A Leica EM TRIM2 paraffin slicer was used to slice the resin embedded samples. A JEOL-200CX transmission electron microscope (TEM) was used to characterize the fine structure of the materials, and a high resolution transmission electron micro- scope (HRTEM) was used for imaging analysis, the acceleration voltage of was greater than or equal to 200 kV, the lattice resolution was less than 0.15 nm and the point resolution was 0.21 nm. 2.3.2 Phase analysis of materials A Shimadzu XRD-6000 X-ray diffractor was used to carry out phase analysis of materials, with Cu Kɑ (λ = 0.15406 nm) as the radioactive source, with a scanning speed of 3 (°)/min and scanning range of 10.0° to 80.0°. 2.3.3 Test of photocatalytic performance 0.2 g of prepared powder sample was dis- persed in 50 mL of Rhodamine B aqueous solution (10 mg/L) and dark treated for 30 min to reach ad- sorption equilibrium. Then, place it in a photo- chemical reactor (YZ-GHX-A, Shanghai Yanzheng Experimental Instrument Co., Ltd.) and degrade Rhodamine B aqueous solution under UV irradia- tion of 500 W mercury lamp. Under continuous stirring and illumination, take out 3 mL mixed solu- tion every 20 min, and centrifuge at the speed of 4000 r/min for 5 min to remove the sediment. Measure the absorption peak of the separated su- pernatant at the wavelength of 554 nm under a UV-Vis gradiometer (UV-1800, Shanghai Mapda Instrument Co., Ltd.). In order to intuitively express the degradation efficiency of Rhodamine B aqueous solution, data processing is carried out through formula (1): Degradation rate /% = C/C0 × 100 (1) In the formula, C0 is the initial mass concen- tration of Rhodamine B aqueous solution, mg/L; C is the mass concentration of the upper clear liquid at an interval, mg/L. 2.3.4 Analysis of UV-Vis diffuse reflectance absorption spectrum A Shimadzu UV-3600 UV-VIS-NIR spectro- photometer was used for UV-Vis diffuse reflection absorption spectrum analysis. The band gap Eg of Ahv-hv image fitted by equation (2): αhv = c(hv – Eg)2 (2) In the formula, α is the absorbance coefficient, which is directly proportional to absorbance A, and it does not affect the fitting result of the band gap width Eg, so in the final image, α is replaced by A, c is a constant. hv is obtained from equation (3): hv = (h × c)/λ (3) In the formula: h is Planck constant, h = 6.63 × 10–34 J; c is the speed of light, taken as 3 × 108 m/s; the unit of hv is J. According to 1 eV = 1.6 × 10–19 J, the obtained hv was converted to eV. 22 3. Results and analysis 3.1 Analysis of the morphology of the PbTiO3-CdS nanocomposite materials Figure 1(a) is the SEM diagram of the perov- skite phase PbTiO3 sample prepared by the hydro- thermal method. As can be seen from Figure 1(a), the PbTiO3 sample is a sheet square with a side length of about 600 nm and a thickness of about 100 nm, with smooth surface, regular morphology and good dispersion. Its large-area exposed surface is (001) crystal surface[21]. Figure 1(b) shows the contrast sample, that is the morphology of CdS par- ticles grown alone without PbTiO3 nanosheet sub- strate. According to Figure 1(b), the CdS particles grown alone were of micron structure with leaf and branch morphology with size of 2–3 μm. The surface is smooth and flat, with clear particle con- tour and aggregation tendency. Figures 1(c)–(e) are SEM images of samples with different CdS loading concentrations. As can be seen from Figure 1(c), most of the PbTiO3 nanosheets in the sample with PbTiO3-CdS mass fraction of 1% have smooth sur- face and no obvious adhesion of CdS nanoparticles. It can be seen from Figure 1(d) that more CdS na- noparticles with a size of about 10 nm are grown on the (001) crystal surface of PbTiO3 nanosheets in the sample with PbTiO3-CdS mass fraction of 2%. Figure 1(e) shows that in the sample with PbTiO3-CdS mass fraction of 3%, CdS is not only dispersed on the (001) crystal plane of PbTiO3, but a small amount of CdS is selectively dispersed on the side of PbTiO3 nanosheets, that is, the (100) or (010) crystal plane. With the increase of CdS load- ing concentration, the amount of particles grown on PbTiO3 nanosheets gradually increases, and its growth crystal surface has obvious selectivity, which may be related to the polarity of the exposed crystal surface of PbTiO3 nanosheets. Under differ- ent initial reactant additions, it can also be observed that there is crystal plane selectivity in the growth of CdS nanoparticles on PbTiO3 nanosheets, that is, it is preferred to nucleate and grow on the strongly polarized plane, and then composite on other crystal planes. (a) PbTiO3 nanopsheet (b) CdS particles (c) PbTiO3-CdS with a mass fraction of 1% (d) PbTiO3-CdS with a mass fraction of 2% (e) PbTiO3-CdS with a mass fraction of 3% Figure 1. SEM images of single-crystal perovskite phase PbTiO3 nanosheets synthesized by the hydrothermal method, CdS particles and PbTiO3-CdS nanocomposite materials with different CdS loading concentrations. 3.2 Phase analysis of PbTiO3-CdS nano- composite materials Figure 2(a) shows the XRD pattern of perov- skite phase PbTiO3 nanosheets prepared by the hy- drothermal method, with all corresponding diffrac- tion peaks (JCPDS: 06-0452), sharp diffraction peaks, good crystallinity and no impurity diffraction peaks. The diffraction peak intensity of its (001) crystal plane is almost equal to the highest peak 23  (101) of the standard diffraction pattern, indicating that the prepared PbTiO3 sample has a large number of (001) exposed surface, which is consistent with the observation results reported in the literature[21] and Figure 1(a). Figure 2(b) shows the XRD pat- terns of CdS particles grown alone and samples with different CdS loading concentrations. It can be seen from the figure that the diffraction peaks of CdS particle samples synthesized separately all correspond to the standard PDF card (JCPDS: 41-1049), with sharp diffraction peaks and no im- purity diffraction peaks. The diffraction peaks of PbTiO3-CdS with a mass fraction of 1%, 2% and 3% are obvious, and the diffraction of PbTiO3 is more intense, and the diffraction peak of CdS is relatively weak. With the increase of CdS loading concentra- tion, the diffraction peak is gradually obvious. It is consistent with the SEM results in Figures 1(c) to (e). And in the XRD diffraction pattern of PbTiO3-CdS nanocomposite materials, the diffrac- tion peak intensity corresponding to the (001) crys- tal plane in PbTiO3 (JCPDS: 06-0452) decreases, which may be related to the selective growth of CdS on the (001) crystal plane of PbTiO3 nanosheets. (a) PbTiO3 nanosheets (b) Single-synthesized CdS particles PbTiO3-CdS with a mass fraction of 1%, 2%, 3% Figure 2. XRD patterns of single-crystal perovskite phase PbTiO3 nanosheets synthesized by the hydrothermal method, sin- gle-synthesized CdS particles and PbTiO3 CdS nanocomposite materials with different CdS loading concentrations. 3.3 Microstructure analysis of PbTiO3-CdS nanocomposite materials In order to further explore the growth and morphology of CdS nanoparticles on the surface of perovskite PbTiO3 nanosheets, the resin embedded sections of PbTiO3-CdS nanocomposite materials were characterized and analyzed by TEM and HRTEM. As shown in Figure 3(a), CdS nanoparti- cles are dispersed on the upper and lower crystal planes of PbTiO3 nanosheets, and an obvious lattice interface is formed, as shown in Figure 3(b). The nanoparticle has complete outline and clear lattice, and its crystal plane spacing is 0.316 nm and 0.245 nm respectively, which corresponds to the (101) and (102) crystal planes of CdS (JCPDS: 41-1049). The crystal plane spacing of PbTiO3 nanosheets is 0.415 nm and 0.390 nm respectively, which corresponds to the (001) and (100) crystal planes of PbTiO3 (JCPDS: 06-0452). Therefore, it is further proved that the prepared samples are PbTiO3-CdS nano- composite materials, and CdS nanoparticles grow selectively on the surface of PbTiO3 nanosheets. 24  (a) TEM (b) HRTEM Figure 3. TEM and HRTEM diagrams of PbTiO3-CdS nanocomposite materials synthesized by the hydrothermal method. 3.4 Growth process of PbTiO3-CdS nano- composite materials In order to further explore the growth process of PbTiO3-CdS nanocomposites, PbTiO3-CdS nanocomposite materials grown under different hy- drothermal reaction time were analyzed. Figure 4 and Figure 5 show the SEM and XRD results of the prepared samples respectively. As can be seen from Figure 4: (a) no obvious CdS nanoparticles were observed on the surface of PbTiO3 nanosheets in the 0.5-h sample, and there was no corresponding dif- fraction peak in XRD. At this time, CdS had not crystallized because the hydrothermal time was too short. (b) Fine CdS nanoparticles with a size of about 10 nm have appeared on the surface of PbTiO3 nanosheets in the 3-h sample. Comparing the XRD pattern of this sample with that of the 0.5-h sample, it can be found that the diffraction peak corresponding to CdS gradually strengthen. (c) The CdS nanoparticles grown on the surface of PbTiO3 nanosheets in the 5-h sample gradually in- creased, and grew on each surface. Compared with the XRD pattern of 3-h sample in (b), the diffrac- tion peak corresponding to CdS in this sample pat- tern was enhanced again. With the extension of the reaction time to 7 h in (d), the size and quantity of CdS nanoparticles on the surface of PbTiO3 nanosheets increase. At this time, CdS nanoparticles can be obviously observed on some surfaces of PbTiO3 nanosheets, with smooth surfaces and no particle adhesion. Therefore, it can be seen that the growth of CdS on the surface of PbTiO3 nanosheets appears selectivity under the growth conditions. With the further extension of the reaction time (Figures 4(e)–(f)), the size of CdS nanoparticles on the surface of PbTiO3 nanosheets remains stable, and its growth selectivity is more obvious. Statisti- cally, a large number of blank exposed crystal sur- faces can be observed, while a large number of CdS particles grow on other crystal surfaces. Figure 5 shows the XRD diffraction results of the prepared samples. It can be seen from the figure that the re- action products have sharp diffraction peaks, which can correspond to two substances of perovskite phase PbTiO3 (JCPDS: 06-0452) and CdS (JCPDS: 41-1049) on the standard PDF card. The diffraction results show that both PbTiO3 substrate and CdS grown on its surface have good crystallinity. Ac- cording to the above analysis results, with the ex- tension of the reaction time, the growth of CdS na- noparticles on PbTiO3 nanosheets was significantly regulated. CdS nanoparticles selectively grow on a crystal surface of PbTiO3 nanosheets. With the in- crease of the hydrothermal time, according to the crystallization thermodynamics, the size of CdS nanoparticles gradually increases and stabilizes. The growth of CdS on the surface of PbTiO3 nanosheets is a process regulated by thermodynam- ics and exposed crystal surface of PbTiO3. 25  (a) 0.5 h (b) 3 h (c) 5 h (d) 7 h (e) 9 h (f) 12 h Figure 4. SEM of PbTiO3-CDs nanocomposite materials synthesized under different hydrothermal reaction time. Figure 5. XRD patterns of PbTiO3-CdS nanocomposite materials synthesized under different hydrothermal reaction time. 3.5 Study on the photocatalytic properties of PbTiO3-CdS nanocomposite materials Based on the above research, the photocatalyt- ic degradation properties of the prepared PbTiO3-CdS nanocomposite materials were studied. Figure 6 shows the efficiency curves of self-degra- dation of Rhodamine B solution and degradation Rhodamine B solution by different samples under UV irradiation. As shown in Figure 6, Rhodamine B solution has slight self-degradation within 120 min, and the degradation rate is 10%, which is caused by the slight increase of the temperature of the stirred solution under UV irradiation in the ex- periment. PbTiO3 nanosheets and PbTiO3 nano- sheets + CdS particles have almost the same degra- dation ability to Rhodamine B solution, and the degradation efficiency is low, which is 40%. It shows that the photocatalytic activity of PbTiO3 nanoparticles and CdS particles is not high. The Rhodamine B solution was significantly degrad- ed by PbTiO3-CdS with a mass fraction of 1%, 2% and 3% under UV light, and the degradation rates were 60%, 64% and 72% respectively. The above results show that with the increase of CdS loading, the catalytic degradation efficiency of PbTiO3-CdS nanocomposite materials on Rhodamine B aqueous solution increases significantly. The degradation efficiency of PbTiO3-CdS with a mass fraction of 3% is 1.8 times higher than that of PbTiO3 nanosheets and PbTiO3 nanosheets + CdS particles. 26  Figure 6. Efficiency curves of self-degradation of Rhodamine B solution and degradation by different samples. Figure 7. UV-Vis diffuse reflection absorption spectrum. Figure 8. Ahv-hv fitting image. Figure 7 shows the UV-Vis diffuse reflectance spectra of different samples. It can be seen from the figure that the prepared PbTiO3-CdS nanocomposite materials have obvious absorption peaks between 425 nm and 520 nm, indicating that PbTiO3-CdS nanocomposite materials have good response to visible light. With the increase of CdS loading con- centration, the response of PbTiO3-CdS nanocom- posite materials to visible light increased slightly. The Ahv-hv fitting image of each sample is fitted 27  according to formula (2), as shown in Figure 8, and the band gap width of each sample is shown in Ta- ble 1. The two band gap widths of PbTiO3-CdS nanocomposite materials not only improve the band gap width of PbTiO3 nanosheets, but also improve the band gap width of CdS particles (Eg ≈ 2.4 eV), so as to reduce the energy required for electronic transition and improve the photocatalytic perfor- mance. With the increase of CdS loading concentra- tion to 3%, the light absorption of PbTiO3-CdS composite samples with a mass fraction of 3% in 425–520 nm band increases significantly. The in- crease of light absorption is conducive to the for- mation of electrons and holes in the composites. The absorption edge of PbTiO3-CdS composite samples with a mass fraction of 3% also has a small amount of red shift, indicating that the band gap of the sample is also reduced accordingly, which is conducive to the absorption of small energy photons, promoting the generation and separation of elec- trons and holes, and further improving the photo- catalytic performance of the sample. This is also consistent with the fact that PbTiO3-CdS samples with a mass fraction of 3% show the highest photo- catalytic activity on Rhodamine B aqueous solution under light. Based on the above analysis, a possible photocatalytic mechanism is proposed: perovskite PbTiO3 nanosheets and CdS are used as light ab- sorption centers to absorb photon energy and pro- duce photogenerated carriers respectively. The CdS surface is the photocatalytic reaction center. The built-in electric field formed by the spontane- ous polarization of PbTiO3 nanosheets promotes the separation of electrons and holes, and the electrons are further transferred to the CdS surface for pho- tocatalytic reaction, so as to improve the photo- catalytic effect of PbTiO3-CdS. Table 1. Band gap width of PbTiO3 nanosheets and PbTiO3-CdS with different loading concentrations Samples Band gap width 1/eV Band gap width 2/eV PbTiO3 nanosheets 2.76 PbTiO3-CdS with a mass fraction of 1% 2.24 2.67 PbTiO3-CdS with a mass fraction of 2% 2.21 2.52 PbTiO3-CdS with a mass fraction of 3% 2.21 2.46 4. Conclusion In this paper, PbTiO3-CdS nanocomposite ma- terials were successfully prepared by the hydro- thermal method, and their microstructure and crys- tal growth process were systematically charac- terized and analyzed. On this basis, the photocata- lytic properties of the prepared PbTiO3-CdS nano- composite materials were evaluated. The main con- clusions are as follows: a) The prepared PbTiO3-CdS nanocomposite materials have regular morphology and good dis- persion; CdS nanoparticles (about 10 nm in size) were selectively grown on the surface of perovskite PbTiO3 nanosheets with good crystallinity. Com- pared with CdS particles with independent nuclea- tion and crystallization, its size decreases sharply, and an obvious interface is formed with PbTiO3 nanosheets. The crystal growth of PbTiO3-CdS nanocomposite materials is a process regulated by the exposed crystal surface of PbTiO3. b) Hydrothermal reaction time is an important thermodynamic condition that strongly affects the crystal growth process of PbTiO3-CdS nanocompo- site materials. With the increase of time, the more sufficient the nucleation and crystal growth of CdS nanoparticles on the surface of PbTiO3 nanosheets, the larger the CdS grain size. c) The prepared PbTiO3-CdS nanocomposite materials can degrade 10 mg/L Rhodamine B solu- tion. With the increase of the mass fraction of PbTiO3-CdS, the photocatalytic degradation effi- ciency of PbTiO3-CdS nanocomposite materials increases. The degradation rate of PbTiO3-CdS nanocomposite materials with a mass fraction of 3% was the highest at 120 min, reaching 72%. 28 Conflict of interest The authors declare that they have no conflict of interest. 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