☆ 4.7 Article Proceedings Paper

Preparation and photocatalytic activity of nanotubes obtained from titanium dioxide

CATALYSIS TODAY (2008)

获取全文
添加到收藏夹

期刊

CATALYSIS TODAY
卷 131, 期 1-4, 页码 3-14

出版社

ELSEVIER SCIENCE BV
DOI: 10.1016/j.cattod.2007.10.015

关键词

TiO2; titanates; nanotubes; hydrothermal process; photocatalytic activity

类别

Chemistry, Applied Chemistry, Physical Engineering, Chemical

向作者/读者索取更多资源

Protocol

社区支持

Reagent

社区支持

The TiO2 sol was prepared hydrothermally in an autoclave from aqueous TiOCl2 solutions using as a starting precursor. Titanate nanotubes were obtained when the sol-gel-derived TiO2 solwas treated chemically with a 10 M NaOH solution and subsequently heated in the autoclave at 150C for 48 h. The samples were characterized using XRD, TEM, SEM, EDX, FF-IR, and BET surface area analyzer. The experimental results revealed that the phase, shape and morphology, surface property and the photocatalytic activity were greatly affected by the calcination temperatures and amount of sodium present in the different samples. On the basis of different experimental evidences, formula Na2Ti3O7 center dot nH(2)O, Na2-xHxTi3O7 center dot nH(2)O and H2Ti3O7 center dot nH(2)O has been proposed for the nanotubes depending on the extent of exchange reaction of sodium with proton. A systematic study, dealing with the photocatalytic activity of the titanate nanotubes, was also carried out as a function of sodium contents and calcination temperatures. The photocatalytic activity of samples, obtained before and after calcination containing different amounts of sodium, was evaluated using the photooxidation of a dye, amaranth, as probe reaction. The as-prepared nanotubes, with or without sodium contents, showed no photocatalytic activities but when the samples containing partial or without sodium ions were heated at different temperatures, photocatalytic activity was drastically increased following the change in phase. (c) 2007 Elsevier B.V. All rights reserved.

作者

我是这篇论文的作者
点击您的名字以认领此论文并将其添加到您的个人资料中。

评论

主要评分

4.7
评分不足

次要评分

新颖性
-
重要性
-
科学严谨性
-
评价这篇论文

推荐

Article Chemistry, Physical

Confined growth and dispersion of FeP nanoparticles in highly mesoporous carbons as efficient electrocatalysts for the hydrogen evolution reaction

Munzir H. Suliman, Turki N. Baroud, Mohammad N. Siddiqui, Mohammad Qamar, Emmanuel P. Giannelis

Summary: The mesopore size of the carbon is a key design parameter for iron monophosphide (FeP) catalysts supported on highly mesoporous carbons (HMCs) for the hydrogen evolution reaction (HER). Smaller mesopores lead to finely dispersed and smaller FeP nanocrystals, while larger mesopores result in larger and agglomerated nanoparticles, impacting the activity of the catalysts. Electrocatalysts based on FeP immobilized on mesoporous carbons show lower overpotential and Tafel slope compared to those based on commercial activated carbon, indicating the importance of mesopore size in determining the performance of electrocatalysts.

INTERNATIONAL JOURNAL OF HYDROGEN ENERGY (2021)

添加到收藏夹
Article Biochemistry & Molecular Biology

Hydrogen Production through Catalytic Water Splitting Using Liquid-Phase Plasma over Bismuth Ferrite Catalyst

Kyong-Hwan Chung, Hyun-Hak Jung, Sun-Jae Kim, Young-Kwon Park, Sang-Chai Kim, Sang-Chul Jung

Summary: This study investigated the characteristics of H-2 production from a decomposition reaction using a bismuth ferrite catalyst, which showed a higher H-2 production rate than the TiO2 photocatalyst due to its ability to respond to both UV and visible light emitted from liquid-phase plasma. The bismuth ferrite catalyst prepared by sol-gel reaction method demonstrated optical properties such as absorption of visible-light over 610 nm and a bandgap of approximately 2.0 eV.

INTERNATIONAL JOURNAL OF MOLECULAR SCIENCES (2021)

添加到收藏夹
Article Electrochemistry

Electrodeposited MnS@Ni(OH)2 core-shell hybrids as an efficient electrode materials for symmetric supercapacitor applications

Perumal Naveenkumar, Munisamy Maniyazagan, Johnbosco Yesuraj, Hyeon-Woo Yang, Nayoung Kang, Kibum Kim, G. Paruthimal Kalaignan, Woo Seung Kang, Sun-Jae Kim

Summary: In this study, MnS@Ni(OH)2 core-shell hybrids were prepared and utilized as electrode materials for supercapacitors, demonstrating excellent performance. This approach may provide a novel, stable, and low-cost electrode material for supercapacitor energy storage devices.

ELECTROCHIMICA ACTA (2022)

添加到收藏夹
Article Electrochemistry

A significant enhancement of cycling stability at fast charging rate through incorporation of Li3N into LiF-based SEI in SiOx anode for Li-ion batteries

Hyeon-Woo Yang, Woo Seung Kang, Sun-Jae Kim

Summary: This study investigates the use of octadecylamine (ODA) as an additional electrolyte additive to improve the ionic conductivity and physicochemical stability of SiOx anode, resulting in enhanced cycling performance and charge/discharge efficiency.

ELECTROCHIMICA ACTA (2022)

添加到收藏夹
Article Energy & Fuels

Fabrication of Nanoneedle and Nanograss Array of Ni-Mixed CuCo2S4@Ni-Foam as Binder-Free Electrode Materials for High-Performance Supercapacitor Applications

Perumal Naveenkumar, Maniyazagan Munisamy, Johnbosco Yesuraj, Kibum Kim, G. Paruthimal Kalaignan, Woo Seung Kang, Sun-Jae Kim

Summary: The surface morphologies of active electrode materials significantly impact the performance of supercapacitors. The CuCo1.0Ni1.0S4 electrode exhibits outstanding specific capacity, rate capability, and cycle performance, making it a promising material for electrochemical energy storage and conversion applications.

ENERGY & FUELS (2022)

添加到收藏夹
Article Biochemistry & Molecular Biology

A Flower-like In2O3 Catalyst Derived via Metal-Organic Frameworks for Photocatalytic Applications

Maniyazagan Munisamy, Hyeon-Woo Yang, Naveenkumar Perumal, Nayoung Kang, Woo Seung Kang, Sun-Jae Kim

Summary: The study effectively synthesized a flower-like indium oxide (In2O3-MF) catalyst using a convenient MOF-based solvothermal self-assembly technique, which exhibited a unique 3D structure, large surface area, and enhanced photocatalytic activity for 4-NP and MB degradation. The In2O3-MF catalyst showed outstanding catalytic performance and high reutilization rate after multiple cycles of catalytic tests.

INTERNATIONAL JOURNAL OF MOLECULAR SCIENCES (2022)

添加到收藏夹
Article Chemistry, Physical

Role of Post-Hydrothermal Treatment on the Microstructures and Photocatalytic Activity of TiO2-Based Nanotubes

Mohammad Qamar, Shabi Abbas Zaidi, Mohd Rafatullah, Mohammad Qutob, Sun-Jae Kim, Qasem A. Drmosh

Summary: The present study investigates the thermal stability and photocatalytic activity of TiO2-based nanotubes after post-hydrothermal treatment. It is found that post-hydrothermal heating improves the photocatalytic activity of the nanotubes by changing their phase structure and morphology. The holes and hydroxide ions are found to play a key role in the dye removal process. Additionally, the photocatalyst exhibits excellent stability and reusability.

CATALYSTS (2022)

添加到收藏夹
Article Biochemistry & Molecular Biology

Carbon-Coated ZnS-FeS2 Heterostructure as an Anode Material for Lithium-Ion Battery Applications

Perumal Naveenkumar, Munisamy Maniyazagan, Nayoung Kang, Hyeon-Woo Yang, Woo-Seung Kang, Sun-Jae Kim

Summary: The construction of carbon-coated heterostructures of bimetallic sulfide is an effective technique to improve the electrochemical activity of anode materials in lithium-ion batteries. In this work, the carbon-coated heterostructured ZnS-FeS2 is prepared by a two-step hydrothermal method, showing higher performance and stability.

INTERNATIONAL JOURNAL OF MOLECULAR SCIENCES (2022)

添加到收藏夹
Article Chemistry, Inorganic & Nuclear

Sulfur-doped SnO2 nanoparticles encased in porous carbon derived from a metal-organic framework for lithium-ion battery anodes

Munisamy Maniyazagan, Perumal Naveenkumar, Hassan Zuhaib, Hyeon-Woo Yang, Woo Seung Kang, Sun-Jae Kim

Summary: This study proposes a Sn-based LIBs anode material called sulfur-doped porous carbon skeleton nanoparticles with SnO2 incorporated using a metal organic framework (MOF) technique (Sn@C-800). This material minimizes SnO2 particle aggregation, volume expansion, and prevents SnO2 from coming into contact with the electrolyte. The inclusion of sulfur increases electrical conductivity and provides sites for lithium-ion storage. Sn@C-800 exhibits a high-rate capacity of 1067 mAh g(-1) at 0.1 A g(-1) and remarkable cycle performance of 1188 mAh g(-1) at 1.0 A g(-1). After 1000 cycles, the reversible capacity increases to 637 mAh g(-1). This paper introduces a method for producing Sn-based LIBs anode materials with outstanding performance.

SOLID STATE SCIENCES (2023)

添加到收藏夹
Article Chemistry, Physical

Building optimal SEI through control of morphology and chemical composition for high-performance lithium-ion batteries

Hyeon-Woo Yang, Munisamy Maniyazagan, Perumal Naveenkumar, Woo Seung Kang, Sun -Jae Kim

Summary: SiOx has potential as an anode material for high energy density lithium-ion batteries due to its high specific capacity, but its long-term durability and storage performance are compromised by continuous solid-electrolyte-interphase (SEI) growth. In this study, we propose an optimal SEI with unique morphology and chemical composition, which facilitates the transport of Li ions during cycling. By adding nanodiamond (ND) and octadecylamine (ODA) additives, we successfully construct nanoscale pillar structure and inorganic Li-N and LiF-rich SEI on the Ti-SiOx@C electrode, resulting in a superior capacity retention of 91.0% at 1C after 500 cycles.

APPLIED SURFACE SCIENCE (2023)

添加到收藏夹
Editorial Material Biochemistry & Molecular Biology

Editorial of Special Issue Materials for Energy Applications 2.0

Sun-Jae Kim

INTERNATIONAL JOURNAL OF MOLECULAR SCIENCES (2023)

添加到收藏夹
Article Chemistry, Physical

SnS nanoplate coated with crystalline silicon-oxy carbide as composite anode for lithium-ion storage applications

Perumal Naveenkumar, Munisamy Maniyazagan, Hyeon-Woo Yang, Woo Seung Kang, Sun -Jae Kim

Summary: SiOC and SnS@SiOC composite materials were prepared by thermal pyrolysis method, while SnS was prepared by CTAB-assisted hydrothermal method. The presence of crystalline carbon phase in SiOC was confirmed by high-magnification TEM images. SEM and TEM images established the nanoplate-like morphology of SnS and the nanoparticle nature of silicon-oxy carbide. X-ray photoelectron spectroscopy validated the chemical state of elements in the SnS@SiOC composite. CV graphs showed that SiOC behaved non-faradic process, while SnS and SnS@SiOC composite exhibited a combined lithium-ion storage mechanism. The rate capability of SnS@SiOC composite was superior to SnS and SiOC electrode materials. The initial discharge capacity of SiOC, SnS, and SnS@SiOC was 1191 mAh g-1, 1007 mAh g-1, and 1315 mAh g-1 @ 0.1 A g-1, respectively. At a current density of 1 A g-1, SiOC, SnS, and SnS@SiOC composite provided the 1000th cycle discharge capacity of 196.8, 437.5, and 570 mAh g-1, respectively. After 800 cycles @ 5 A g-1, SnS and SnS@SiOC composite delivered a discharge capacity of 448.7 and 491.8 mAh g-1, with capacity retention of 94% and 90%, respectively. Silicon oxy carbide and SnS synergistically increase lithium-ion storage capacity and cycle stability for long-term energy storage and conversion applications.

JOURNAL OF ALLOYS AND COMPOUNDS (2023)

添加到收藏夹
Article Materials Science, Multidisciplinary

Selenium-decorated nitrogen-rich honeycomb-like g-C3N4 as anode materials for lithium ion batteries

Hassan Zuhaib, Maniyazagan Munisamy, Naveenkumar Perumal, Hyeon-Woo Yang, Woo Seung Kang, Sun -Jae Kim

Summary: Heteroatom doping is an efficient method to modify the electronic properties of carbon for better lithium storage capacity. Here, we report a straightforward approach to synthesize selenium-decorated honeycomb-like g-C3N4 (Se-H-g-C3N4) for the anode of a Li-ion battery. The Se doping significantly widened the gap between carbon sheets, providing more active sites for Li-ion storage and enhancing the diffusion rate. As a result, Se-H-g-C3N4 outperformed bulk g-C3N4 and honeycomb-like g-C3N4 (H-g-C3N4) in terms of rate capability and specific capacity.

MATERIALS CHEMISTRY AND PHYSICS (2023)

添加到收藏夹
Article Electrochemistry

A carbon microsphere-modified ZnS-MnS@C composite anode for Li-ion battery applications

Perumal Naveenkumar, Munisamy Maniyazagan, Nayoung Kang, Hyeon-Woo Yang, Woo Seung Kang, Sun-Jae Kim

Summary: In this study, carbon-coated hetero-structured ZnS-MnS composite was successfully prepared using a simple hydrothermal method. The carbon content in the composite was determined by Raman spectroscopy. The crystallinity and phase purity of the composite were confirmed by X-ray diffraction patterns, and the nanoparticle morphology was observed by microscopy techniques.

ELECTROCHIMICA ACTA (2023)

添加到收藏夹
Article Chemistry, Physical

Morphologically controlled rapid fabrication of rhodium sulfide (Rh2S3) thin films for superior and robust hydrogen evolution reaction

Muhammad Ali Ehsan, Alaaldin Adam, Abdul Rehman, Abbas Saeed Hakeem, Anvarhusein A. Isab, Mohammad Qamar

Summary: Rhodium sulfide (Rh2S3) thin films with self-organized nanostructured morphologies were fabricated using aerosol-assisted deposition, showing high catalytic activity for the hydrogen evolution reaction in water splitting. The blooming flower-like structure of Rh2S3/NF-80 exhibited the highest catalytic performance, with the lowest reported overpotentials and a Tafel slope suggesting Volmer-Heyrovsky kinetic model. These films have the potential for large-scale application and may perform equivalently in various catalytic operations.

SUSTAINABLE ENERGY & FUELS (2021)

添加到收藏夹
Article Chemistry, Applied

Operando characterisation of the products of Fischer-Tropsch synthesis in a fixed-bed reactor studied by magnetic resonance

Qingyuan Zheng, Jack H. Williams, Scott Elgersma, Mick D. Mantle, Andrew J. Sederman, G. Leendert Bezemer, Constant M. Guedon, Lynn F. Gladden

Summary: In this study, a pilot-scale fixed-bed reactor compatible with NMR/MRI was developed for Fischer-Tropsch synthesis. Multiple magnetic resonance techniques were applied to quantitatively characterize different product species within catalyst pellets, providing valuable information for catalyst and reactor optimization.

CATALYSIS TODAY (2024)

添加到收藏夹
Article Chemistry, Applied

Ambient pressure operando catalytic characterization by combining PM-IRRAS with planar laser-induced fluorescence and surface optical reflectance imaging

Lisa Ramisch, Sebastian Pfaff, Sabrina M. Gericke, Edvin Lundgren, Johan Zetterberg

Summary: We present a combination of optical operando techniques that allow simultaneous measurement of adsorbed species on catalyst surfaces, monitoring of surface oxide formation, and imaging of the gas phase above the catalyst surface. The experimental setup was validated by studying CO oxidation on Pd(100) at different pressures, revealing the effects of pressure on the heterogeneous catalytic reaction.

CATALYSIS TODAY (2024)

添加到收藏夹
Article Chemistry, Applied

Insights into the influence of feed impurities on catalytic performance in the solvent-free dimerization of renewable levulinic acid

Marta Paniagua, Gabriel Morales, Juan A. Melero, Daniel Garcia-Salgado

Summary: The influence of common impurities in levulinic acid on the catalytic performance of different acid catalysts for bio-jet fuel production was studied. It was found that furfural had the greatest detrimental effect on catalyst performance, while propyl-sulfonic acid-modified SBA-15 and sulfonic acid resin Amberlyst-70 showed good regeneration ability.

CATALYSIS TODAY (2024)

添加到收藏夹
Article Chemistry, Applied

Open Zn-URJC-13 efficient catalyst for mild CO2 transformation using bulky epoxides

Jesus Tapiador, Pedro Leo, Guillermo Calleja, Gisela Orcajo

Summary: This study presents a new MOF material, Zn-URJC-13, with acid and basic sites, permanent porosity, and high affinity to CO2 molecules. The Zn-URJC-13 catalyst exhibits efficient performance in CO2 cycloaddition reactions and can be reused multiple times.

CATALYSIS TODAY (2024)

添加到收藏夹
Article Chemistry, Applied

Effect of supports on the kind of in-situ formed ZnOx species and its consequence for non-oxidative propane dehydrogenation

Dan Zhao, Vita A. Kondratenko, Dmitry E. Doronkin, Shanlei Han, Jan-Dierk Grunwaldt, Uwe Rodemerck, David Linke, Evgenii V. Kondratenko

Summary: This study demonstrates the potential of cheap and commercially available Zr or Ti-based supports and ZnO to serve as active and selective catalysts for propane dehydrogenation (PDH). The catalytically active species formed in situ under PDH conditions consist of isolated ZnOx. ZnOx on the surface of LaZrOx shows the highest rate of propene formation.

CATALYSIS TODAY (2024)

添加到收藏夹
Article Chemistry, Applied

Diels-Alder conversion of biomass-derived furans and ethylene to renewable aromatics over mesoporous titanium phosphate

Hanbyeol Kim, Jung Rae Kim, Young-Kwon Park, Jeong-Myeong Ha, Jungho Jae

Summary: In this study, metal phosphates were used as catalysts for biomass conversion to produce sustainable aromatics through DielsAlder cycloaddition reactions. The effects of synthesis method, activation method, and P/Ti molar ratio on the structure and acid properties of titanium phosphate catalysts were systematically studied. The mesoporous titanium phosphate catalyst synthesized by hydrothermal method at 180℃ for 12 h followed by ethanol refluxing at 60℃ for 24 h at a molar P/Ti ratio of 1 showed the highest surface area and acid site density.

CATALYSIS TODAY (2024)

添加到收藏夹
Article Chemistry, Applied

High propylene selectivity in methanol conversion over metal (Sm, Y, and Gd) modified HZSM-5 catalysts in the methanol to propylene process

Yasin Khani, Sumin Pyo, Kwang-Eun Jeong, Chul-Ung Kim, Moonis Ali Khan, Byong-Hun Jeon, Kun-Yi Andrew Lin, Siyoung Q. Choi, Young-Kwon Park

Summary: A protonated form of Zeolite Socony Mobil-5 (H-ZSM-5) catalyst was synthesized through a hydrothermal method using different sources of silica. The effect of loading the catalyst with yttrium, samarium, and gadolinium on the acidic properties was investigated. Among the metal-loaded catalysts, the Sm/LHZ catalyst showed the best performance in the methanol to propylene conversion due to its high amount of weak and intermediate acid sites, while the Gd-LHZ catalyst increased the selectivity towards ethane and propane.

CATALYSIS TODAY (2024)

添加到收藏夹
Article Chemistry, Applied

Enantioselective synthesis of spiroimidazolones by synergistic catalysis

Michael Franc, Ivana Cisarova, Jan Vesely

Summary: The present study investigates an enantioselective cyclization of enals with imidazolone derivatives catalyzed by a combination of achiral Pd(0) complex and chiral secondary amine. Corresponding spirocyclic imidazolones were produced in high yields with moderate diastereoselectivity and excellent enantioselectivity. The developed co-operative catalytic methodology provides a highly substituted spirocyclic scaffold with four stereogenic centers under mild conditions.

CATALYSIS TODAY (2024)

添加到收藏夹
Article Chemistry, Applied

Influence of the synthesis method of Cu/Y zeolite catalysts for the gas phase oxidative carbonylation of methanol to dimethyl carbonate

Mauro Alvarez, Jennifer Cueto, David P. Serrano, Pablo Marin, Salvador Ordonez

Summary: This study focuses on improving the formulation and preparation methods of catalysts for the production of dimethyl carbonate. By using suitable catalyst preparation methods and copper salt precursors, the researchers successfully produced catalysts with optimal performance for dimethyl carbonate formation.

CATALYSIS TODAY (2024)

添加到收藏夹
Article Chemistry, Applied

Influence of Ag particle size and Ag : Al2O3 surface ratio in catalysts for the chloride-promoted ethylene epoxidation

Claudia J. Keijzer, Luc C. J. Smulders, Dennie Wezendonk, Jan Willem de Rijk, Petra E. de Jongh

Summary: This study investigates the catalytic behavior of alpha-alumina supported silver catalysts in the presence of chloride. It is found that the particle size of silver can affect the selectivity of the catalyst, but different strategies lead to different results. In this size range, the selectivity of ethylene oxide is correlated to the Ag : Al2O3 surface ratio.

CATALYSIS TODAY (2024)

添加到收藏夹
Article Chemistry, Applied

Acid and base catalysis of SrTiO3 nanoparticles for C-C bond-forming reactions

Takeshi Aihara, Wataru Aoki, Michikazu Hara, Keigo Kamata

Summary: The development of acid-base bifunctional catalysts is important for promoting specific chemical transformations. In this study, Ti-based perovskite oxides were synthesized and used as catalysts for two C-C bond-forming reactions (cyanosilylation and Knoevenagel condensation). The highly pure SrTiO3 nanoparticles with a high specific surface area exhibited the highest catalytic performance, and could be easily recovered and reused.

CATALYSIS TODAY (2024)

添加到收藏夹
Article Chemistry, Applied

New Sn-Mg-Al hydrotalcite-based catalysts for Baeyer-Villiger oxidation of β-cyclocitral

Olga Gorlova, Petra Pribylova, Eliska Vyskocilova, Katerina Peroutkova, Jan Kohout, Iva Paterova

Summary: This study investigates the Baeyer-Villiger oxidation of beta-cyclocitral using tin-modified mixed oxides as catalysts. The optimal reaction conditions and the effects of various factors on the reaction course and selectivity were determined. The results show that tin-modified mixed oxides exhibit high activity and selectivity in the oxidation reaction.

CATALYSIS TODAY (2024)

添加到收藏夹
Article Chemistry, Applied

Catalytic upgrading of lignin-derived bio-oils over ion-exchanged H-ZSM-5 and H-beta zeolites

M. I. Avila, M. M. Alonso-Doncel, L. Briones, G. Gomez-Pozuelo, J. M. Escola, D. P. Serrano, A. Peral, J. A. Botas

Summary: The catalytic fast pyrolysis of lignin using ion-exchanged zeolite catalysts showed significant improvements in bio-oil quality and the production of aromatic hydrocarbons and oxygenated compounds.

CATALYSIS TODAY (2024)

添加到收藏夹
Article Chemistry, Applied

Simultaneous catalytic dehydration of methanol and ethanol: How ZSM-5 acidity addresses conversion and products distribution

Enrico Catizzone, Giorgia Ferrarelli, Paolo Bruno, Girolamo Giordano, Massimo Migliori

Summary: The acid-catalysed alcohol conversion reaction is a promising route for de-fossilization strategies. Research on pure alcohol conversion and simultaneous dehydration of mixed alcohols have shown different product compositions, with the type and distribution of acid sites affecting the reaction mechanism.

CATALYSIS TODAY (2024)

添加到收藏夹
Article Chemistry, Applied

Effect of oxygen vacancy modification of ZnO on photocatalytic degradation of methyl orange: A kinetic study

Alireza Ranjbari, Juho Kim, Jihee Yu, Jiyun Kim, Mireu Park, Nayoung Kim, Kristof Demeestere, Philippe M. Heynderickx

Summary: This study investigated a novel kinetic model for the adsorption and photocatalytic degradation of methyl orange using commercial ZnO and reduced ZnO photocatalysts. The results provided new insights into the interaction of catalysts with molecules of different charges and compared with a previous study on methylene blue. The presence of oxygen vacancies in ZnO and their effects on adsorption and photocatalytic degradation were analyzed, and the photocatalytic degradation rate of reduced ZnO was found to increase significantly.

CATALYSIS TODAY (2024)

添加到收藏夹
研讨会 海报 问题 讨论圈 基金 期刊 论文 科研社交 资讯集成 审稿人 关于我们 常见问题 移动App 隐私条款 使用条款
© Peeref 2019-2024. All rights reserved.