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Pentagraphene: Structure, Properties, and Electronic Device Applications
Published in Swamini Chopra, Kavita Pande, Vincent Shantha Kumar, Jitendra A. Sharma, Novel Applications of Carbon Based Nano-Materials, 2023
Khurshed A. Shah, M. Shunaid Parvaiz, Mubashir Qayoom
Pentagraphene is a two-dimensional carbon allotrope that has been proposed theoretically very recently. Although its practical synthesis/implementation is yet a crucial challenge, some of its unique electrical, thermal, mechanical, magnetic, and optical properties highlighting promising application in nano-electronic devices have motivated researchers to study the material thoroughly. The zero bandgap characteristic of graphene limits its application in various cases, whereas PG is a quasi-direct bandgap semiconductor with a bandgap of 3.25 eV. It can withstand a temperature as high as 1,000 K. Thermal conductivity of PG is significantly lower in comparison to graphene, which enhances the possibility of using PG in thermoelectric devices. The mechanical strength of PG also outperforms graphene. There would have an enormous application of PG in the biomedical and sensor field as nano-auxetic materials. However, despite such a wide spectrum of interesting properties, the practical realization of pristine PG is a crucial challenge. Judicious chemical functionalization could be a possible solution for achieving a stable PG structure. Functionalized PG is shown to be more stable than its pristine counterpart suggesting the possibility of synthesis of PG functionalized state as a precursor. Interestingly, PG was proposed to be synthesized by hydrogen intercalation from T12-carbon in the pioneering work on PG.
Theories of Human Development
Published in Richard Kerslake, Elizabeths Templeton, Lisanne Stock, Revision Guide for MRCPsych Paper A, 2018
Very recently, significant efforts have focused on the stabilization of a novel carbon allotrope, named monolayer penta-graphene (MPG) [16–19]. Penta-graphene (PG) is extracted from the bulk T12-carbon phase. This phase is obtained by heating an interlocking-hexagon-based metastable carbon phase at high temperatures [20]. It is found that the MPG is an indirect band-gap semiconductor with a band gap of ~3.25 eV [16, 18, 21], which is smaller than SiC [22], BN [23, 24], and BeO [25] nanostructures. Those studies showed that this structure has obtained dynamical, thermal, and mechanical stability. Furthermore, Wu et al. [17] used first-principles lattice dynamics and iterative solution of the phonon Boltzmann transport equation (BTE) to investigate the thermal conductivity of MPG and its more stable derivative, hydrogenated monolayer penta-graphene (HMPG). They showed that in contrast to the hydrogenation of graphene, which leads to a dramatic decrease in thermal conductivity, HMPG shows a notable increase in thermal conductivity, which is much higher than that of MPG. Also, a theoretical study has reported the stability and electronic properties of one-dimensional penta-graphene nanoribbon (PGNR) [26]. Their calculations predict that PGNR is dynamically stable; it is mechanically flexible tolerating up to 11.5% of axial strain. They also explored the electronic properties of the PGNRs with different widths. It is found that the band gap of wider PGNRs changes only marginally with further increasing the ribbon width, which opens up the possibility of a stable nanoribbon with a large band gap [26]. Tien et. al. investigated the electronic structures and the I-V characteristics of the sawtooth-sawtooth PGNRs (SSPGNRs) under a sequence of uniaxial strains in a range from 10% compression to 10% stretch [27]. In this strained range, carbon atoms still keep a pentagon network, but with the changing bond lengths. The fundamental physical properties (band structure, I-V characteristic) of SSPGNRs seem to be more sensitive to compressive strain than the stretch strain. The current intensity of the compressive-SSPGNR is by 2 orders of magnitude compared to that of the tensile-SSPGNR at the same strain in a range from 6% to 10%.
The electronic properties and electron transport of sawtooth penta-graphene nanoribbon under uniaxial strain: ab-initio study
Published in Philosophical Magazine, 2020
Vo Van On, Le Nhat Thanh, Nguyen Thanh Tien
Very recently, it is well known that penta-graphene (PG), a pentagon form 2D carbon allotrope, that could be obtained from T12-carbon by disruption the covalent bonds between layers [12]. PG has been expected to possess several notable characteristics. It is buckling (not completely planar), its 2D projection resembles the Cairo tiling, being composed of fused pentagons. Based on calculations, they have confirmed that the PG is a semiconductor with a quasi-direct band gap [12] being attractive for application in opto-electronic field.