Research progress on penta-graphene and its related materials: Properties and applications

Large second harmonic generation in a penta-CdO2sheet exfoliated from its bulk phase

“…15 Since the theoretical prediction of penta-graphene, 16 over one hundred new pentagonal 2D materials have been theoretically proposed and some, experimentally synthesized. 17,18 It is interesting to note that the top-down approach has been successfully used for the synthesis of pentagonal 2D materials. For example, penta-PdSe 2 was prepared by exfoliating bulk PdSe 2 in the marcasite phase, 19 and penta-FeS 2 was synthesized by chemically cleaving bulk iron pyrite via liquid-phase exfoliation.…”

Large Negative Poisson’s Ratio and Anisotropic Mechanics in New Penta-PBN Monolayer

“…In recent years, a new class of two-dimensional (2D) Cairo-pentagonal lattice monolayers and their one-dimensional (1D) nanoribbon are drawing considerable attention due to their extraordinary chemical and physical properties , identified by both experiments − and theories. − Unlike ultra-thin planar hexagonal graphene, the low-symmetric, trilayered, and buckled geometry of penta monolayers allow them more degrees of freedom to possess novel mechanical, piezoelectric, electronic, thermal, and optical properties. − In addition, the inheritance of the robust band topology and visible light-harvesting direct-band gap semiconducting to metallic electronic behavior of penta monolayers make them highly desirable in cutting-edge technological devices such as optomechanical sensors, lithium-ion batteries, and solar cells. ,, …”

“…In recent years, a new class of two-dimensional (2D) Cairo-pentagonal lattice monolayers and their one-dimensional (1D) nanoribbon are drawing considerable attention due to their extraordinary chemical and physical properties 1 , 2 identified by both experiments 3 − 6 and theories. 7 − 13 Unlike ultra-thin planar hexagonal graphene, 14 the low-symmetric, trilayered, and buckled geometry of penta monolayers allow them more degrees of freedom to possess novel mechanical, piezoelectric, electronic, thermal, and optical properties.…”

Penta-OsP2 and penta-Rhs2 sheets derived from marcasite and pyrite with low lattice thermal conductivity

“…Since the proposal of penta-graphene, 1 a pentagon-based two-dimensional (2D) carbon allotrope, a family of over 100 pentagon-based 2D materials has been reported with novel physical properties and vast potential applications. 2,3 For instance, a negative Poisson's ratio (NPR) has been found in penta-BN 2 , 4,5 penta-ZnO 2 , 6 and penta-PdSe 2 , 7,8 topological electronic states have been reported in penta-RuS 4 , 9 MoS 2 , 10 and p-PbS 2 , 11 ferromagnetism and antiferromagnetism have been found in penta-MnN 2 , 12 and CoS 2 , 13 ferroelasticity was reported in penta-PdS 2 , 14 piezoelectric responses have been found in penta-BCN, 15,16 penta-CNP 17 and some transition metal-based ternary pentagonal sheets, 18 and second harmonic generation was predicted in penta-ZnS 2 . 19 Meanwhile, considerable effort has been made to synthesize such pentagon-based materials.…”