One- and two-dimensional penta-graphene-like structures

The discovery of graphene led to the emergence of a two-dimensional (2D) world and the investigation of numerous 2D carbon allotropes through computational simulation methods. Among these, penta-graphene (PG) has received significant attention and has served as the basis for several new 2D inorganic structures. In this context, this study aimed to investigate one- and two-dimensional PG-like structures (P-XC2 where X = C, Si or Ge) and their electronic, structural, dielectric, piezoelectric and catalytic properties via density functional theory simulations. The results showed that P-XC2 systems have an indirect band gap energy ranging from 2.65 to 3.55 eV. Furthermore, P-GeC2 exhibits the highest dielectric and piezoelectric constants values, followed by P-SiC2 and P-GeC2, while penta-graphene has higher elastic constants compared to P-SiC2 and P-GeC2. Notably, armchair and zigzag nanotubes exhibit elastic constants closer to those observed for the respective 2D structure, with penta-graphene showing the biggest differences. Additionally, smaller nanotubes exhibit the largest dielectric constant, which is larger than the respective monolayers. Finally, the band alignment indicates that PXC2 and their respective nanotubes could favor hydrogen production through water splitting.