Investigation of the bulk and surface properties of CdSe: insights from theory

Szemjonov, Alexandra; Pauporté, Thierry; Ciofini, Ilaria; Labat, Frédèric

doi:10.1039/c4cp02886d

Cited by 18 publications

(18 citation statements)

References 70 publications

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“…In more detail, for the synthesis NPLs were separated by centrifugation and were re-suspended in 10 mL of hexane. We investigated these NPLs in detail, from both an experimental and theoretical points of view in our previous works [17][18][19]. TEM views of the NPL are shown in Figure S7 (Supplementary Material).…”

Section: Nanoplatelets Preparation and Ligand Exchangementioning

confidence: 99%

Ligand exchange on CdSe nanoplatelets for the solar light sensitization of TiO2 and ZnO nanorod arrays

Szemjonov

Tasso

Ithurria

et al. 2019

Journal of Photochemistry and Photobiology A: Chemistry

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In quantum dot (QD) solar cells, the ex situ sensitization of wide band gap semiconductors (WBSCs) makes it possible to control the shape and the passivation of the nanosized sensitizer. Hence, ex situ techniques can be used to investigate how the band gap of the sensitizers affects the performance of quantum dot solar cells. The latter can be precisely controlled in 1D confined structures such as quasi-2D nanoplatelets (NPLs), the thickness of which is defined with an atomic precision. In this work, we tested and thoroughly characterized the attachment of 7, 9 and 11 monolayers thick CdSe NPLs (as well as QDs for the sake of comparison) to ZnO and to TiO2 nanorods. A crucial point of the ex situ techniques is the choice of bifunctional ligands that link the nanosized sensitizers to the WBSCs. Besides the well-known mercaptopropionic acid, we also studied two 'atomic linkers' (OHand SH-) to minimize the distance between the sensitizer and the oxide. The asprepared systems have been analyzed by UV/VIS absorption and Raman spectroscopy.

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Section: Nanoplatelets Preparation and Ligand Exchangementioning

confidence: 99%

Ligand exchange on CdSe nanoplatelets for the solar light sensitization of TiO2 and ZnO nanorod arrays

Szemjonov

Tasso

Ithurria

et al. 2019

Journal of Photochemistry and Photobiology A: Chemistry

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“…As mentioned, CdSe can appear in two crystalline forms, i.e., the cubic (sphalerite or zinc-blende, space group F-43m) and the hexagonal (wurtzite, space group P63 mc) structures. 80,81 Figure 1d shows the XRD pattern of CdSe-OCPs, in comparison to that of CdSe-QDs, as representative of the crystalline structure of the CdSe-OCP core. These latter evidence a pure sphalerite phase (ICDD card no.…”

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confidence: 99%

Octapod-Shaped CdSe Nanocrystals Hosting Pt with High Mass Activity for the Hydrogen Evolution Reaction

et al. 2020

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The design of efficient electrocatalysts for electrochemical water splitting with minimal amount of precious metal is crucial to attain renewable and sustainable energy conversion. Here, we report the use of a network of CdSe branched colloidal nanocrystals, made of a CdSe core and eight CdSe pods (so-called octapods), able to host on their pods Pt particles, and thus catalyzing water splitting reactions. Thanks to the octapod shape, the resulting Pt-hosting network is mechanically trapped onto carbon nanotube buckypaper, providing mechanically flexible and binder-free electrodes. We found that such hierarchical configuration maximizes the mass activity and the utilization efficiency of Pt for the hydrogen evolution reaction (HER). At a potential of -0.15 V vs. reversible hydrogen electrode, the Pt/octapod network-based electrodes display a Pt mass activity on the HER of ~166 A mg -1 and ~42 A mg -1 in acidic and alkaline media, respectively. These values correspond to turnover frequencies of ~168 s -1 and ~42 s -1 , respectively, which are in that order 14 and 21 times higher compared to commercially available Pt/C benchmarks. The strong chemical and mechanical interactions between the Pt and the octapod surface, along with pod-aided adhesion of the Pt/octapod network to the buckypaper, result in a long-term durability (>20 h) of the HER-activity in both media. These results experimentally prove that the exploitation of our network of branched nanocrystals hosting Pt particles can circumvent the durability issues of the catalysts while adopting either ultralow Pt loadings or benchmarking carbon-supported Pt nanocrystals. Our work opens up prospects for using porous networks made by branched nanocrystals as catalysts with ultralow amount of noble metals and controlled catalytic properties. nanocrystals 21,22,[23][24][25][26][27][28][29][30]34 or monolayers 31,32 are typically embedded/deposited into/onto appropriate supports, as it is done in benchmark catalysts, such as Vulcan XC-72-supported Pt nanocrystals (Pt/C). These supports are preferably high-surface area and/or electrically conductive scaffolds. 33,35,36 However, Pt nanocrystals/monolayers often suffer from instability caused by Pt dissolution or delamination during the water splitting reactions. 37,38 The preparation of single Pt atom catalysts, e.g., Pt atoms on CeO2, 39 Al2O3, 40 TiN, 41 TiC, 41,42 carbon, 43 MXenes, 22 is challenging since the single Pt atoms tend to coalesce into clusters during the catalyst synthesis and especially during the electrocatalytic processes, 44,45 quickly degrading the theoretical maximum MAPt. 46 Therefore, it is essential to isolate and immobilize Pt atoms and to strengthen the adhesion and chemical stability of the Pt nanocrystals/monolayers, to prevent the aforementioned issues. This is achievable through the Pt localization into/onto the crystal lattice of an hosting matrix/substrate through controlled chemical interactions. 22,[47][48][49][50] The structural mismatch at the Pt/support interface can be exploi...

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“…39 Several studies can be found concerning the electronic and structural properties of bulk CdSe. [62][63][64][65] In particular, a previous study by some of us 39 led to the development of a computational procedure, based on the use of global hybrid functionals, that serves as a good description of the structural and electronic features of CdSe bulk structures. The same protocol is applied here with the aim of choosing the best DFT approach.…”

Section: Cdse Bulkmentioning

confidence: 99%

“…The same protocol is applied here with the aim of choosing the best DFT approach. However, while in Szemjonov et al 39 a D2 dispersion correction scheme 66 was adopted in combination with each functional tested, we employed here the D3 40 As mentioned above, to simulate the UV-Vis. spectra of the two CdSe bulk phases considered, the SC-Ewald approach was employed.…”

Section: Cdse Bulkmentioning

confidence: 99%

“…All ground state periodic calculations were carried out at the DFT level with the Crystal17 code, 37,38 which solves self‐consistently both Hartree–Fock (HF) and Kohn–Sham equations using atom‐centered Gaussian orbitals as basis set. Based on a previous benchmark on the performances of different exchange‐correlation functionals for CdSe bulk 39 performed by some of us, the global hybrid B3PW91 functional has been selected for all periodic calculations. Additional semi‐empirical London‐type dispersion corrections were employed for the optimization of CdSe bulk, considering the DFT‐D3 scheme 40 …”

Section: Computational Detailsmentioning

confidence: 99%

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ModelingUV–Visspectra of low dimensional materials using electrostatic embedding: The case ofCdSe

2021

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We present a generalization of a self-consistent electrostatic embedding approach (SC-Ewald) devised to investigate the photophysical properties of 3D periodic materials, to systems in one-or two-dimensional (2D) reduced periodicity. In this approach, calculations are carried out on a small finite molecular cluster extracted from a periodic model, while the crystalline environment is accounted for by an array of point charges which are fitted to reproduce the exact electrostatic potential (at ground or the excited state) of the infinite periodic system. Periodic density functional theory (DFT) calculations are combined with time dependent DFT calculations to simulate absorption and emission properties of the extended system under investigation. We apply this method to compute the UV-Vis. spectra of bulk and quantumconfined 0D quantum dots and 2D extended nanoplatelets of CdSe, due to their relevance as sensitizers in solar cells technologies. The influence of the size and shape of the finite cluster model chosen in the excited state calculations was also investigated and revealed that, although the long-range electrostatics of the environment are important for the calculation of the UV-Vis, a subtle balance between short-and long-range effects exists. These encouraging results demonstrate that this self-consistent electrostatic embedding approach, when applied in different dimensions, can successfully model the photophysical properties of diverse material classes, making it an attractive low-cost alternative to far more computationally demanding electronic structure methods for excited state calculations.

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Investigation of the bulk and surface properties of CdSe: insights from theory

Cited by 18 publications

References 70 publications

Ligand exchange on CdSe nanoplatelets for the solar light sensitization of TiO2 and ZnO nanorod arrays

Ligand exchange on CdSe nanoplatelets for the solar light sensitization of TiO2 and ZnO nanorod arrays

Octapod-Shaped CdSe Nanocrystals Hosting Pt with High Mass Activity for the Hydrogen Evolution Reaction

ModelingUV–Visspectra of low dimensional materials using electrostatic embedding: The case ofCdSe

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