The recent technological revolution in nanoscience has created a huge potential to build highly sensitive, low-cost and power efficient portable sensors. Here, we have investigated the novel nano-porous penta-graphene nanotube (PGNT) device for detection and separation of halogen gases like fluorine (F2), chlorine (Cl2), bromine (Br2) and iodine (I2). The host carbon atoms are selectively removed to create the nanopores on the tube surface. 1, 2, 3 and 4 host carbon atoms are removed from the surface to create vacancies which were then investigated for detection and separation of halogen gases using functionalisation of pore edges. The I-V measurements were performed to establish the gas detection application of these novel porous structures. Furthermore, interaction energy graphs were obtained which show efficient separation of various halogen molecules by functionalising the pores with F2, Cl2 and H atoms.