Gas Sensing and Photocatalytic Applications of Graphene Oxide Annealed at Various Temperature.

Researchers employed the improved Hummers' method to synthesize graphene oxide (GO) from graphite, chosen for its faster kinetics, enhanced safety, and reduced toxicity. Thermal annealing was conducted at 0°C, 200°C, 300°C, and 400°C. The acidity of GO was minimized through repeated centrifugation, rinsing, and decanting. The resulting films were characterized for structural, morphological, elemental, optical, gas-sensing, and photocatalytic properties. FESEM micrographs revealed nanoflake distributions across the substrate, while EDS confirmed elemental composition with precise mass and atomic percentages. Optical analysis showed high absorbance coefficients that increased with annealing temperature. Thermal conductivity was high, and FTIR spectroscopy identified characteristic functional groups. Gas-sensing tests demonstrated peak sensitivity to hydrogen sulfide (H2S) at 100 ppm. Photocatalytic studies revealed a maximum azo dye degradation efficiency of 98.2%, though efficiency decreased with higher annealing temperatures. Pseudo-first-order rate constants (k) increased with annealing temperature, indicating enhanced reaction kinetics. Overall, the synthesized GO variants exhibit promising multifunctional properties, making them strong candidates for integration into gas-sensing and photocatalytic applications.