Hexagonal nanoplatelets of Ni–Mn oxide implanted reduced graphene oxide for high response in humidity sensing

The hydrothermal synthetic approach was used to synthesize unique nanoplatelets of manganese(IV) nickel(II) oxide (NMN) and successively implanted into reduced graphene oxide to develop Ni–Mn oxide implanted reduced graphene oxide (NMNG). The Raman study, X-ray diffraction, transmission electron microscopy, energy dispersive X-ray spectroscopy, scanning electron microscopy, X-ray photoelectron spectroscopy, surface porosity study, etc., were used to explore its structure–property correlation. The humidity sensing performance of NMNG was assessed, and its sensing mechanism was explored. The higher concentration of H⁺ or H₃O⁺ on the surface of NMNG showed higher conductivity and generated higher responses. Notably, RGO introduction can enhance sensor performance up to 100 times. The sensitivity of NMNG was greatly improved surpassing the most efficient humidity sensors. NMNG displayed excellent sensitivity and a fast recovery (5 s). Additionally, NMNG can proficiently sense humidity at a wide range of 8–81 relative humidity (RH)% which reveals its promising performance in support of nanoplatelets structure and highly accessible surface area of RGO.