Search query: spectrum tailored defective 2D

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abstract: The wide spectral range of the solar flux with undesirable diffused energy distribution remains a substantial impediment to the high efficiency utilization of the whole spectrum. Here, inspired by the spectrally selective sunlight utilization of plants, a spectrum tailored solar harnessing aerogel is conceived. It is composed of oxygen vacancy (Ov) defect rich semiconductor HNb3O8 (D HNb3O8) nanosheets and polyacrylamide (PAM) framework to perform all in one photochemical and photothermal full solar energy conversion. The aerogel selectively utilizes the whole solar spectrum, in which high energy ultraviolet (UV) photon is converted into high redox potential electron hole pairs, while low energy visible near infrared (NIR) photons are transformed into heat. The designed solar absorber polymer composite shows energy harnessing conversion capability with desired heat insulation, reactant enrichment, rapid mass diffusion and capillary pumping characteristics, thus realizing a high efficient steam generation and photochemical activity. This cooperative photochemical and photothermal solar energy conversion, at respective optimal working spectrum, holds great promise for optimizing and maximizing the solar energy utilization, as well as opening up opportunities to explore simultaneous multifunctional usage of solar energy.
author_names: Min-Quan Yang

Chuan Fu Tan

Wanheng Lu

Kaiyang Zeng

Ghim Wei Ho
title: Spectrum Tailored Defective 2D Semiconductor Nanosheets Aerogel for Full Spectrum Driven Photothermal Water Evaporation and Photochemical Degradation
year: 2020

abstract: Tailoring light matter interactions in monolayer MoS2 is critical for its use in optoelectronic and nanophotonic devices. While significant effort has been devoted to enhancing the photoluminescence intensity in monolayer MoS2, tailoring of the emission spectrum including complex excitonic states remains largely unexplored. Here, we demonstrate that the peak emission wavelengths of the A and B excitons can be tuned up to 40 and 25 nm, respectively, by integrating monolayer MoS2 into a plasmonic nanocavity with tunable plasmon resonances. Contrary to the intrinsic photoluminescence spectrum of monolayer MoS2, we are also able to create a dominant B exciton peak when the nanocavity is resonant with its emission. Additionally, we observe a 1200 fold enhancement of the A exciton emission and a 6100 fold enhancement of the B exciton emission when normalized to the area under a single nanocavity and compared to a control sample on thermal oxide.
author_names: Jiani Huang

Gleb M Akselrod

Tian Ming

Jing Kong

Maiken H Mikkelsen
title: Tailored emission spectrum of 2D semiconductors using plasmonic nanocavities
year: 2017

abstract: Photocatalytic water splitting is a promising way to produce hydrogen fuel from solar energy. In this regard, the search for new photocatalytic materials that can efficiently split water into hydrogen is essential. Here, using first principles simulations, we demonstrate that the dual defective SnS2 (Ni SnS2 VS) by both single atom nickel doping and sulfur monovacancies, becomes a promising two dimensional photocatalyst compared with SnS2. The Ni SnS2 VS monolayer, in particular, exhibits a suitable band alignment that perfectly overcomes the redox potentials for overall water splitting. The dual defective monolayer displays remarkable photocatalytic activity, a spatially separated carrier, a broadened optical absorption spectrum, and enhanced adsorption energy of H2O. Therefore, the dual defective SnS2 monolayer can serve as an efficient photocatalyst for overall water splitting to produce hydrogen fuel. Furthermore, a novel dual defect method can be an effective strategy to enhance the photocatalytic behavior of 2D materials; it may pave inroads in the development of solar fuel generation.
author_names: Batjargal Sainbileg

Ying-Ren Lai

Li-Chyong Chen

Michitoshi Hayashi
title: The dual defective SnS2 monolayers: promising 2D photocatalysts for overall water splitting.
venue: Physical chemistry chemical physics PCCP
year: 2019

abstract: Bi dimensional nano materials and related heterostructures are establishing themselves as intriguing material systems for the development of a new class of electronic, photonic and plasmonic devices with ad hoc properties, that can be engineered "from scratch" Huge potential can be envisaged in a variety of application fields, ranging from saturable absorbers to optical modulators, from optical communication modules to spintronics, from near field components to photodetectors. Their peculiar band structure and electron transport characteristics, which can be easily manipulated via layer thickness control, suggest they could also form the basis for a new generation of highperformance devices operating in the Terahertz frequency range (1 10 THz) of the electromagnetic spectrum. This talk will review latest achievements in the developments of active and passive THz photonic and nano electronic devices exploiting 2D nano materials and combined heterostructures and will discuss future perspectives of this rapidly developing research field.
author_names: Miriam Serena Vitiello
title: Tailored nano electronics and photonics with 2D materials
venue: 2018 43rd International Conference on Infrared, Millimeter, and Terahertz Waves (IRMMW THz)
year: 2018

abstract: In NMR analysis of complex organic molecules, low natural abundance of 13C and the low resolution of two dimensional (2D) experiments are significant difficulties. Also challenging is the analysis of a mixture spectrum without separation, which has been limited to simple molecules. Through nonuniform sampling using modified heteronuclear multiple bond correlation combined with indirect covariance, a high resolution 13C 13C correlation spectrum was obtained with 1H sensitivity. Built on the thus obtained 13C 13C connectivities, deconvolution of the mixture spectra was achieved through a new signal processing procedure, termed DECODE, tailored to the indirect covariance eigendecomposition. When applied to a complex natural product mixture of rotenone and brucine with many quaternary carbons, the method resolved very close carbon peaks and extracted clean individual spectra. Essentially providing molecule wide 13C connectivities for complex molecules from 1H detected 2D spectra, our approach should prove useful in many areas of NMR analysis.
author_names: Jin Wook Cha

Sunghyouk Park
title: Extraction of Individual Spectra from Mixture Data Based on High Resolution 13C 13C NMR Correlation Spectrum and DECODE Procedure.
venue: Analytical chemistry
year: 2020

abstract: The possibility to record a full 2D spectrum in less than a second using ultrafast 2D NMR (UF2DNMR) is beneficial in many applications. However, the spatial encoding process on which UF2DNMR is based sets specific constraints on the spectral width and resolution of the resulting spectra. To overcome these limitations, a tailored encoding method using spatial/spectral pulses (SPSP) can be employed as an alternative to the traditional linear spatial encoding of interactions. Here we analyze and further develop this alternative spatial encoding strategy. We first carry out numerical simulations to describe the features of bidimensional SPSP pulses. Sidebands are identified along the spectral dimension of the excitation profile. An interleaved excitation scheme is then developed and implemented experimentally to suppress the unwanted signals that arise from these harmonic sidebands. Two examples are shown to illustrate the potential of the proposed approach. An ultrafast selective TOCSY spectrum is recorded to access sub spectra and fully assign 1H NMR resonances of individual residues of cyclosporin A. An ultrafast HSQC spectrum of a mixture of metabolites is recorded with an optimized spectral width in the spatially encoded dimension.
author_names: Bertrand Plainchont

Patrick Giraudeau

Jean-Nicolas Dumez
title: Interleaved spatial/spectral encoding in ultrafast 2D NMR spectroscopy.
venue: Journal of magnetic resonance
year: 2019

abstract: Van der Waals (vdW) interfaces based on 2D materials are promising for optoelectronics, as interlayer transitions between different compounds allow tailoring of the spectral response over a broad range. However, issues such as lattice mismatch or a small misalignment of the constituent layers can drastically suppress electron photon coupling for these interlayer transitions. Here, we engineered type II interfaces by assembling atomically thin crystals that have the bottom of the conduction band and the top of the valence band at the G point, and thus avoid any momentum mismatch. We found that these van der Waals interfaces exhibit radiative optical transitions irrespective of the lattice constant, the rotational and/or translational alignment of the two layers or whether the constituent materials are direct or indirect gap semiconductors. Being robust and of general validity, our results broaden the scope of future optoelectronics device applications based on two dimensional materials. Type II van der Waals interfaces formed by different two dimensional materials enable robust interlayer optical transitions, regardless of common issues such as lattice constant mismatch, layer misalignment or whether the constituent compounds are direct or indirect band semiconductors.
author_names: Nicolas Ubrig

E A Ponomarev

Johanna Zultak

Daniil Domaretskiy

Viktor Zolyomi

Daniel J Terry

James Howarth

I Gutierrez-Lezama

Alexander A Zhukov

Zakhar R Kudrynskyi

Zakhar D Kovalyuk

Amalia Patane

Takashi Taniguchi

Kenji Watanabe

Roman V Gorbachev

Vladimir I Fal'ko

Alberto F Morpurgo
title: Design of van der Waals interfaces for broad spectrum optoelectronics
venue: Nature Materials
year: 2020

abstract: Light harvesting capacity and photoexcited charge carrier separation ability are two crucial requirements for high efficiency semiconductor photocatalysis. Here, we report a plasmonic Z scheme nanohybrid by hydrothermally in situ growing two dimensional (2D) oxygen deficient molybdenum oxide (MoO3 x) nanoplates onto 2D graphitic carbon nitride (g C3N4) nanosheets. The resultant 2D/2D MoO3 x/g C3N4 nanohybrids not only construct a unique Z scheme heterojunction, which improves the photogenerated charge carrier separation efficiency, but also possess numerous oxygen vacancies on the surface of MoO3 x, which could excite its plasmon resonance for extending spectrum adsorption. Importantly, the plasmon resonance can be readily designed by tailoring the oxygen vacancy concentration via an annealing in air. Benefiting from the synergetic effect of interfacial Z scheme heterojunction and the tunable plasmon resonance of MoO3 x, the as obtained nanohybrids achieve a remarkably improved photocatalytic H2 evolution efficiency. The optimal Z scheme heterostructure presents 2.6 and 1.7 times higher of H2 evolution rate as compared to pure g C3N4 and the annealing nanohybrid under visible light irradiation. Even under light irradiation with wavelength longer than 590 nm, the hybrid photocatalyst displays a H2 generation rate as high as 22.8 umol h 1 due to the plasmonic sensitization effect. The result in our work can provide an alternative for fabricating Z scheme heterostructures that take advantages of Z scheme induced charge carrier separation, accompanied with plasmon enhanced light harvesting of semiconductor to advance the solar energy conversion efficiency in photocatalysis.
author_names: Yanzhen Guo

Binbin Chang

Ting Wen

Shouren Zhang

Min Zeng

Nantao Hu

Yanjie Su

Zhi Yang

Bao-cheng Yang
title: A Z scheme photocatalyst for enhanced photocatalytic H2 evolution, constructed by growth of 2D plasmonic MoO3 x nanoplates onto 2D g C3N4 nanosheets.
venue: Journal of colloid and interface science
year: 2020

abstract: Abstract This paper developed the new route decision making method that implements the wave added resistance estimation method using forecast 2d wave spectra in a frequency and a direction domain specified through a ship's voyage route. In the accepted conventional method, a 1d idealized spectrum is applied to estimate the wave added resistance calculation in the process of performance evaluation in the route decision making algorithm. Wave added resistance estimation using an 1d idealized spectrum assumes that the statistical characteristics of the sea do not vary over the ship's route with regard to geography and season. In the real world, the characteristics of the sea continually vary according to the voyage route in which a vessel passes by. This paper provides the method that calculates the added resistance of waves using forecast 2d wave spectra, that provided tailor made stochastic data at any particular time and position along the route of the vessel.The difference of the wave added resistance estimation using conventional 1d idealized spectrum method and the proposed forecast 2d wave spectra method is investigated by the comparative study of the estimation results, model tests, and the measured power during the real voyage case of 173K LNGC in the Pacific and Atlantic ocean.
author_names: Sung-Pyo Kim
title: The development of route decision making method based on tailor made forecast 2d wave spectra due to the operation profile of the vessel
year: 2020

abstract: Abstract Efficient solar driven evaporation has engendered great interests as a sustainable and environmental approach for solar energy utilization. The development of high performance photo absorbers is of paramount importance for realizing efficient solar evaporation. Among the light harvesting materials, transition metal oxide (TMO) is regarded as one of the most promising substitutes for photothermal conversion. Here, two dimensional (2D) defective tungsten oxide (WOx) nanosheets are prepared via introducing oxygen vacancies in WO3. It demonstrates that the novel 2D plasmonic WOx nanosheets can be used as high performance photo absorbers for efficient solar steam generation, displaying broadband and intense light absorption in the full solar spectrum due to the tunable localized surface plasmon resonances. Its evaporation efficiency reaches 78.6% under 1 kW/m2 (one sun) irradiation. The result reveals that adjusting the surface nanostructures and morphologies of TMO can be thought to be a potential strategy to promote the light harvesting performance for solar steam generation. This study is significant for further exploring potential applications of plasmonic semiconductors in sterilization, desalination, and photothermal power through solar steam generation.
author_names: Xin Ming

Ankang Guo

Gang-Qiang Wang

Xianbao Wang
title: Two dimensional defective tungsten oxide nanosheets as high performance photo absorbers for efficient solar steam generation
year: 2018