Professor Pedro Venezuela

@article{D3CP05949A,

title = {Optical spectra and exciton radiative lifetimes in bulk transition metal dichalcogenides},

author = {Cesar E. P. Villegas and Enesio Marinho and Pedro Venezuela and Alexandre Reily Rocha},

url = {http://dx.doi.org/10.1039/D3CP05949A},

doi = {10.1039/D3CP05949A},

year  = {2024},

date = {2024-04-16},

urldate = {2024-01-01},

journal = {Phys. Chem. Chem. Phys.},

pages = {-},

publisher = {The Royal Society of Chemistry},

abstract = {The optical response of layered transition metal dichalcogenides (TMDCs) exhibits remarkable excitonic properties which are important from both fundamental and device application viewpoints. One of these phenomena is the observation of intralayer/interlayer excitons. While much effort has been done to characterize excitons in monolayer TMDCs and their heterostructures, a quite limited number of works have addressed the exciton spectra of their bulk counterparts. In this work, we employ ab initio many-body perturbation calculations to investigate the exciton dynamics and spectra of bulk 2H-MX2 (M = Mo, W, and X = S, Se). For molybdenum-based systems, we find the presence of interlayer excitons at energies higher than the first bright exciton (XA), with non-negligible strength intensity. Our results also show that interlayer excitons in tungsten-based systems are almost degenerate in energy with XA and possess very small oscillator strengths when compared with molybdenum-based systems. At room temperature, and considering the thermal exciton fine-structure population for the XA-exciton, we estimate effective radiative lifetimes in the range of ∼4–14 ns. For higher energy excitons we predict longer effective lifetimes of tens of nanoseconds.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{GONTIJO2024129279,

title = {Resonant enhancement of the 2G Raman band in twisted bilayer graphene},

author = {Rafael N. Gontijo and Marcus V. O. Moutinho and Ariete Righi and Po-Wen Chiu and Pedro Venezuela and Marcos A. Pimenta},

url = {https://www.sciencedirect.com/science/article/pii/S0254058424004048},

doi = {https://doi.org/10.1016/j.matchemphys.2024.129279},

issn = {0254-0584},

year  = {2024},

date = {2024-04-12},

urldate = {2024-01-01},

journal = {Materials Chemistry and Physics},

pages = {129279},

abstract = {Raman spectroscopy is an extremely useful tool to characterize graphene systems. The strongest Raman features are the first-order G band and the second-order 2D and 2D′ bands, which are the overtones of the double resonance D and D’ bands. However, the 2G band, which is the overtone of the G band, is not usually observed in the spectra of monolayer graphene and of crystalline graphite. In this work, we present an experimental and theoretical investigation of the resonance Raman spectra in twisted bilayer graphene (TBG) with different twisting angles and using several laser excitation energies in the NIR and visible ranges. We observed that the 2G band is enhanced when the incident photons are in resonance with the transition between the van Hove singularities in the density of states of the TBG. We show that the 2G band has three contributions (2G1, 2G2 and 2G3), that are not dispersive by changing the laser excitation energy. We also present theoretical calculations showing that the 2G1 and 2G2 bands are related to combinations of the in-phase (IP) and out-of-phase (OP) vibrations of the atoms in the different layers. The Raman excitation profiles (REPs) of the 2G peaks are upshifted in comparison with the REP of the G band. This behavior was confirmed theoretically using a graphene tight binding model. We conclude that the different resonance behavior comes from the fact that the G band is a first-order process whereas the 2G band is second-order processes giving rise to overall different resonance conditions.},

keywords = {Electronic structure, Resonant Raman spectroscopy, Twisted bilayer graphene},

pubstate = {published},

tppubtype = {article}

}

@article{BERTOLINI2024110049,

title = {The effect of lithium battery overpotential on sulfurized-polyacrylonitrile (SPAN): A theoretical approach},

author = {Samuel Bertolini and Pedro Venezuela and Arnaud Delcorte},

url = {https://www.sciencedirect.com/science/article/pii/S2352152X23034485},

doi = {https://doi.org/10.1016/j.est.2023.110049},

issn = {2352-152X},

year  = {2023},

date = {2023-12-14},

urldate = {2024-01-01},

journal = {Journal of Energy Storage},

volume = {78},

pages = {110049},

abstract = {The use of SPAN as a positive electrode for lithium‑sulfur batteries (LiSB) has demonstrated that, the material preserves a high specific capacity for several cycles. Through the recharging cycle, e.g. in Li-ion batteries, overpotential reactions can occur and promote degradation of the electrode material. In this work, we investigate the overpotential reactions that may occur in the presence of SPAN and cyclized-polyacrylonitre (cPAN). To approach this, ab initio molecular dynamics (AIMD) was used, and depletion of electrons was created in the system, thus inducing overpotential reactions in SPAN and cPAN. The simulations indicate that overpotential reactions tend to degrade the system, enabling reactions between the polymer and the solvent, as well as generating new branches in the polymer due to interactions with solvent radicals. The presence of different salts can also impact the overpotential reactions either by reacting with the solvent or by necessitating higher overpotential values.},

keywords = {Density functional theory, Lithium-sulfur batteries, Overpotential reaction, Sulfurized-polyacrylonitrile},

pubstate = {published},

tppubtype = {article}

}

@article{PimentaMartins2023,

title = {Pressure tuning of minibands in MoS2/WSe2 heterostructures revealed by moiré phonons},

author = {Luiz G. Pimenta Martins and David A. Ruiz-Tijerina and Connor A. Occhialini and Ji-Hoon Park and Qian Song and Ang-Yu Lu and Pedro Venezuela and Luiz G. Cançado and Mário S. C. Mazzoni and Matheus J. S. Matos and Jing Kong and Riccardo Comin},

doi = {10.1038/s41565-023-01413-3},

issn = {1748-3395},

year  = {2023},

date = {2023-06-15},

journal = {Nat. Nanotechnol.},

publisher = {Springer Science and Business Media LLC},

keywords = {and Optics, Atomic and Molecular Physics, Bioengineering, Biomedical Engineering, Condensed Matter Physics, Electrical and Electronic Engineering, General Materials Science},

pubstate = {published},

tppubtype = {article}

}

@article{RODRIGUES2023118087,

title = {Improving the sensitivity of graphyne nanosensor by transition metal doping},

author = {Debora C. M. Rodrigues and Rodrigo G. Amorim and A. Latgé and Pedro Venezuela},

url = {https://www.sciencedirect.com/science/article/pii/S0008622323003329},

doi = {https://doi.org/10.1016/j.carbon.2023.118087},

issn = {0008-6223},

year  = {2023},

date = {2023-01-01},

journal = {Carbon},

volume = {212},

pages = {118087},

abstract = {The concern with air quality and safety urges for design and development of new gas sensors. Graphyne presents comparable electronic mobility and mechanical properties to graphene, with the advantage of naturally allowing single-atom dispersion into acetylenic pores. Therefore, we investigate the detection ability of transition metal (TM: Fe and Ni) doped graphyne (Gy) toward CO, NO, NO2, and CO2 gas molecules. Our aim is to engineer the electronic characteristics and further improve the sensing properties. We model the sensing device using TM-doped Gy nanoribbons (TM-GyNR) using density functional theory combined with non-equilibrium Green’s functions. Most of the gases presented chemical adsorption on the TM-GyNR, with slightly weaker interaction for gas/NiGyNR systems than gas/FeGyNR. These differences produced recovery times compatible with room temperature detectors for CO and NO (NiGyNR) and CO2 (FeGyNR) gases. We obtain gas sensitivity as high as 117% for CO/FeGyNR and 300% for NO2/NiGyNR. Due to mutual differences in binding energies and sensitivity among the gases, NiGyNR and FeGyNR also present high selectivity to distinguish the target molecules. Finally, our findings suggest that TM functionalization of graphynes is a promising strategy for engineering the sensitivity of gas nanosensors.},

keywords = {DFT, Electronic transport, Gas sensor, Graphyne, Transition metal},

pubstate = {published},

tppubtype = {article}

}

@article{Carozo2023,

title = {Raman spectroscopy of a few layers of bismuth telluride nanoplatelets},

author = {Victor Carozo and Bruno R. Carvalho and Syed Hamza Safeer and Leandro Seixas and Pedro Venezuela and Mauricio Terrones},

doi = {10.1039/d3na00585b},

issn = {2516-0230},

year  = {2023},

date = {2023-00-00},

journal = {Nanoscale Adv.},

publisher = {Royal Society of Chemistry (RSC)},

abstract = {Exploring the art of tailoring electronic and phonon properties in a few layers of Bi2Te3 crystals through layer variation with Raman spectroscopy.},

keywords = {and Optics, Atomic and Molecular Physics, Bioengineering, General Chemistry, General Engineering, General Materials Science},

pubstate = {published},

tppubtype = {article}

}