“…In the last ten years, poly(o-phenylenediamine) (POPD) was intensively studied, with several applications being reported in the following area: (i) fuel cells [ 1 ], (ii) sensors [ 2 , 3 ], (iii) solar cells [ 4 ], lithium-ion batteries [ 5 ] and so on. Depending on the oxidizing agents used in chemical polymerization, i.e., K 2 Cr 2 O 7 and HCl, CuCl 2 , (NH 4 ) 2 S 2 O 8 , H 2 O 2 or FeCl 3, the POPD morphological structures of the type of ellipsoidal particles [ 6 ], micro-belts [ 7 ], quantum dots [ 8 ], fiber like microstructures with square prism shapes [ 9 ] and microfibers [ 10 ], respectively, were reported. A wide range of POPD-based composites have been synthesized in the presence of various oxides (e.g., TiO 2 [ 11 ], ZnO [ 12 ]) or carbon nanoparticles (e.g., carbon nanohorns [ 13 ], reduced graphene oxide [ 14 ], carbon nanohollow [ 15 ], carbon nanotubes [ 16 , 17 ]).…”