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Nayana K, Sunitha AP. Amphi-Luminescent MoS 2 nanostructure for photocatalytic splitting of water and removal of Methylene Blue. SPECTROCHIMICA ACTA. PART A, MOLECULAR AND BIOMOLECULAR SPECTROSCOPY 2024; 314:124190. [PMID: 38554694 DOI: 10.1016/j.saa.2024.124190] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/22/2023] [Revised: 02/24/2024] [Accepted: 03/25/2024] [Indexed: 04/02/2024]
Abstract
Chemical dyes used in the textile industries are one of the major pollutants in water. Methylene blue (MB) is a commonly seen dye that creates hazardous health problems. In this article the photocatalytic degradation of MB by the nanocatalyst MoS2 (Nano-MoS2) and carbon dot (C Dots) incorporated MoS2 (Nano-CD-MoS2) is reported. The photocatalytic degradation of MB is analyzed based on the electron-hole recombination rate of the catalyst. Photoluminescence emission exhibited by the catalyst is used as a key indicator to probe the electron-hole recombination rate. Nano-MoS2 was synthesized hydrothermally at 180 0C for 8 h from ammonium tetra thiomolybdate (ATTM). C Dot was prepared following a green root from ash guard extract which later mixed with Nano-MoS2 and kept in an autoclave at a temperature 140 °C for 4 h to get Nano-CD-MoS2. The photoluminescence (PL) and photocatalytic behavior of Nano-MoS2 and Nano-CD-MoS2 and their application for water splitting and water purification are reported. The incorporation of graphene and artificial C Dot into MoS2 nanostructures are reported to increase the conductivity and active edge sites of MoS2 that enhances the photocatalytic action. Since green C Dots are eco-friendly and easily synthesizable than artificial C Dots, as a novel study, this article investigated the influence of green C Dots on the PL and photocatalytic performance of nanosized MoS2. Nano-MoS2 and Nano-CD-MoS2 exhibited both upconversion and downconversion PL; accordingly the nanostructures were termed as amphi-luminescent. The amphi-luminescence property widens the photon absorption range and hence enhances the catalytic degradation of dyes. Nano-MoS2 which exhibited lesser intensity of amphi-luminescence emission compared to Nano-CD-MoS2 showed better results in degradation of MB. C Dots may bind with the valence band electrons of MoS2, resulting in the reduction of dangling bonds. Dangling bonds can trap photo-induced excitons to hinder the rate of electron-hole recombination. So, fast electron-hole recombination occurs in Nano-CD-MoS2 than Nano-MoS2. Fast electron-hole recombination supports radiative electron-hole recombination while suppresses the non-radiative energy transfer of electrons and causes high PL intensity. However, according to the energy level diagram, Nano-MoS2 with minimal electron-hole recombination rate is more favorable for O2/O2-,.OH/ OH- and.OH/H2O reactions that facilitate MB degradation. Photocatalytic activity of catalysts were confirmed by measuring the photocurrent from a simple custom-made two-electrode water photolysis cell where the nanocatalysts were dispersed in electrolyte. Lead and steel rods were used as electrodes. Multimeter was used to measure current. Nano-MoS2 exhibited better performance with a maximum photocurrent of 141 µA. Influence of green C Dots in energy levels, PL and photocatalysis of MoS2 and mechanisms of PL and degradation of MB are thoroughly investigated in this article.
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Affiliation(s)
- K Nayana
- Department of Physics, Government Victoria College, Affiliated to University of Calicut, Palakkad, Kerala 678001, India; Department of Physics, N. S. S. College, Affiliated to University of Calicut, Ottapalam, Kerala 679103, India
| | - A P Sunitha
- Department of Physics, Government Victoria College, Affiliated to University of Calicut, Palakkad, Kerala 678001, India.
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K N, A P S. Unveiling the Radiative Electron-Hole Recombination of MoS 2 Nanostructures at Extreme pH Conditions. J Fluoresc 2024:10.1007/s10895-024-03616-w. [PMID: 38381234 DOI: 10.1007/s10895-024-03616-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2023] [Accepted: 02/12/2024] [Indexed: 02/22/2024]
Abstract
Nanostructures of MoS2 are in wide research for optoelectronic, energy and biological applications. Opto-electronic and biological applications requires the tuning of photoluminescence properties of MoS2 nanostructures. In this article, nanosized MoS2 is hydrothermally synthesized, and photoluminescence at extreme pH conditions (pH 1 and 13) is examined. As the photoluminescence gives a key to probe the radiative electron-hole recombination, here, photoluminescence emissions are used as an indicator to suggest the pattern of electron-hole recombination in the material at extreme pH conditions. Raman spectroscopy, dynamic light scattering, Scanning electron microscopic image and energy dispersive x-ray analysis are done for material confirmation. At pH 1 and 13 as-synthesized nanostructured MoS2 exhibited both upconversion and downconversion photoluminescence. The intensity of photoluminescence is varied with respect to pH. Excitation-dependent photoluminescence mechanisms and preliminary understanding on the ratio of quantum yields and life span of excited state of as-synthesized nanostructured MoS2 are unveiled here.
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Affiliation(s)
- Nayana K
- Department of Physics, Government Victoria College, Affiliated to University of Calicut, Palakkad, 678001, Kerala, India
- Department of Physics, N. S. S. College, Affiliated to University of Calicut, Ottapalam, Palakkad, 679103, Kerala, India
| | - Sunitha A P
- Department of Physics, Government Victoria College, Affiliated to University of Calicut, Palakkad, 678001, Kerala, India.
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Wang J, Liao T, Wei Z, Sun J, Guo J, Sun Z. Heteroatom-Doping of Non-Noble Metal-Based Catalysts for Electrocatalytic Hydrogen Evolution: An Electronic Structure Tuning Strategy. SMALL METHODS 2021; 5:e2000988. [PMID: 34927849 DOI: 10.1002/smtd.202000988] [Citation(s) in RCA: 59] [Impact Index Per Article: 19.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/19/2020] [Revised: 12/27/2020] [Indexed: 06/14/2023]
Abstract
Electrocatalytic water splitting for hydrogen production is an appealing way to reduce carbon emissions and generate renewable fuels. This promising process, however, is limited by its sluggish reaction kinetics and high-cost catalysts. Construction of low-cost and high-performance non-noble metal-based catalysts have been one of the most effective approaches to address these grand challenges. Notably, the electronic structure tuning strategy, which could subtly tailor the electronic states, band structures, and adsorption ability of the catalysts, has become a pivotal way to further enhance the electrochemical water splitting reactions based on non-noble metal-based catalysts. Particularly, heteroatom-doping plays an effective role in regulating the electronic structure and optimizing the intrinsic activity of the catalysts. Nevertheless, the reaction kinetics, and in particular, the functional mechanisms of the hetero-dopants in catalysts yet remains ambiguous. Herein, the recent progress is comprehensively reviewed in heteroatom doped non-noble metal-based electrocatalysts for hydrogen evolution reaction, particularly focus on the electronic tuning effect of hetero-dopants in the catalysts and the corresponding synthetic pathway, catalytic performance, and activity origin. This review also attempts to establish an intrinsic correlation between the localized electronic structures and the catalytic properties, so as to provide a good reference for developing advanced low-cost catalysts.
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Affiliation(s)
- Jing Wang
- College of Materials and Environmental Engineering, Institute of Advanced Magnetic Materials, Hangzhou Dianzi University, Hangzhou, Zhejiang, 310018, P. R. China
| | - Ting Liao
- School of Mechanical, Medical and Process Engineering, Centre for Materials Science, Queensland University of Technology, Brisbane, Queensland, 4001, Australia
| | - Zhongzhe Wei
- Institute of Industrial Catalysis, College of Chemical Engineering, Zhejiang University of Technology, Hangzhou, 310032, P. R. China
| | - Junting Sun
- College of Materials and Environmental Engineering, Institute of Advanced Magnetic Materials, Hangzhou Dianzi University, Hangzhou, Zhejiang, 310018, P. R. China
| | - Junjie Guo
- College of Materials and Environmental Engineering, Institute of Advanced Magnetic Materials, Hangzhou Dianzi University, Hangzhou, Zhejiang, 310018, P. R. China
| | - Ziqi Sun
- School of Chemistry and Physics, Centre for Materials Science, Queensland University of Technology, Brisbane, Queensland, 4001, Australia
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Huang H, Yan M, Yang C, He H, Jiang Q, Yang L, Lu Z, Sun Z, Xu X, Bando Y, Yamauchi Y. Graphene Nanoarchitectonics: Recent Advances in Graphene-Based Electrocatalysts for Hydrogen Evolution Reaction. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2019; 31:e1903415. [PMID: 31496036 DOI: 10.1002/adma.201903415] [Citation(s) in RCA: 112] [Impact Index Per Article: 22.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/29/2019] [Revised: 07/23/2019] [Indexed: 05/24/2023]
Abstract
Under the double pressures of both the energy crisis and environmental pollution, the exploitation and utilization of hydrogen, a clean and renewable power resource, has become an important trend in the development of sustainable energy-production and energy-consumption systems. In this regard, the electrocatalytic hydrogen evolution reaction (HER) provides an efficient and clean pathway for the mass production of hydrogen fuel and has motivated the design and construction of highly active HER electrocatalysts of an acceptable cost. In particular, graphene-based electrocatalysts commonly exhibit an enhanced HER performance owing to their distinctive structural merits, including a large surface area, high electrical conductivity, and good chemical stability. Considering the rapidly growing research enthusiasm for this topic over the last several years, herein, a panoramic review of recent advances in graphene-based electrocatalysts is presented, covering various advanced synthetic strategies, microstructural characterizations, and the applications of such materials in HER electrocatalysis. Lastly, future perspectives on the challenges and opportunities awaiting this emerging field are proposed and discussed.
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Affiliation(s)
- Huajie Huang
- College of Mechanics and Materials, Hohai University, Nanjing, 210098, China
| | - Minmin Yan
- College of Mechanics and Materials, Hohai University, Nanjing, 210098, China
| | - Cuizhen Yang
- College of Mechanics and Materials, Hohai University, Nanjing, 210098, China
| | - Haiyan He
- College of Mechanics and Materials, Hohai University, Nanjing, 210098, China
| | - Quanguo Jiang
- College of Mechanics and Materials, Hohai University, Nanjing, 210098, China
| | - Lu Yang
- College of Mechanics and Materials, Hohai University, Nanjing, 210098, China
| | - Zhiyong Lu
- College of Mechanics and Materials, Hohai University, Nanjing, 210098, China
| | - Ziqi Sun
- School of Chemistry Physics and Mechanical Engineering, Queensland University of Technology (QUT), 2 George Street, Brisbane, QLD, 4001, Australia
| | - Xingtao Xu
- State Key Laboratory of Hydrology-Water Resources and Hydraulic Engineering, Hohai University, Nanjing, 210098, China
| | - Yoshio Bando
- Institute of Molecular Plus, Tianjin University, No. 11 Building, No. 92 Weijin Road, Nankai District, Tianjin, 300072, P. R. China
- Australian Institute for Innovative Materials, University of Wollongong, Squires Way, North Wollongong, NSW, 2500, Australia
- International Center for Materials Nanoarchitectonics (WPI-MANA), National Institute for Materials Science, 1-1 Namiki, Tsukuba, Ibaraki, 305-0044, Japan
| | - Yusuke Yamauchi
- School of Chemical Engineering and Australian Institute for Bioengineering and Nanotechnology (AIBN), The University of Queensland, Brisbane, QLD, 4072, Australia
- Department of Plant & Environmental New Resources, Kyung Hee University, 1732 Deogyeong-daero, Giheung-gu, Yongin-si, Gyeonggi-do, 446-701, Korea
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