Synthesis of amorphous cobalt hydroxide nanosheets and electrochemical performance according to phase transition into crystalline cobalt oxides

Flexible Humidity Sensor Based on a Graphene Oxide–Carbon Nanotube-Modified Co3O4 Nanoparticle-Embedded Laser-Induced Graphene Electrode

“…As presented in Figure f, the Raman spectra of both the GO–MWCNT humidity-responsive composite and the Co 3 O 4 –LIG electrode material reveal the manifestation of characteristic D and G band peaks, , situated approximately at 1350 and 1585 cm –1 , respectively. In addition, the Co 3 O 4 –LIG electrode shows the other two distinguished peaks at about 2687 and 2930 cm –1 , belonging to 2D and D + G band peaks, respectively. , Generally, the D band serves as a prevalent indicator for characterizing defects and disorder within carbon network structures, whereas the G band originates from the vibrational activity of C atoms located within the sp 2 plane. , The incorporation of Co 3 O 4 within the composite electrode is discernible through the appearance of Raman peaks at around 477 and 673 cm –1 , corresponding to the E g and A 1g modes of cobalt, respectively . Owing to the relatively limited cobalt content within the carbon-doped matrix, these cobalt-related peaks exhibit notable attenuation compared to the D and G peaks associated with carbon components.…”

“…58,59 The incorporation of Co 3 O 4 within the composite electrode is discernible through the appearance of Raman peaks at around 477 and 673 cm −1 , corresponding to the E g and A 1g modes of cobalt, respectively. 33 Owing to the relatively limited cobalt content within the carbon-doped matrix, these cobalt-related peaks exhibit notable attenuation compared to the D and G peaks associated with carbon components.…”

“…Metal oxide nanomaterials as a semiconductor material have unique physical and chemical properties and high sensitivity − and are often used in various sensor applications. Especially for cobalt oxide nanomaterials, due to their better hydrophilicity and optimized doping performance for composite materials, the use of cobalt oxide for humidity sensors has been reported. − Zhang et al introduced a flexible humidity sensor featuring three-dimensional hollow-structured cobalt oxide particles, which exhibited an impressive response time of 1 s and a recovery time of 13.5 s . Nonetheless, the intricate fabrication procedure associated with this sensor poses challenges for commercial-scale production.…”