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The chemically reduced graphene oxide (rGO) was prepared by the reduction of graphene oxide by hydrazine hydrate. By varying the reduction time (10 min, 1 h, and 15 h), oxygen functional groups on rGO were tremendously controlled and they were named RG1, RG2, and RG3, respectively. Here, we investigate the impact of oxygen functional groups on the detection of ammonia and toluene at room temperature. Their effect on sensing mechanism was analyzed by first-principles calculation-based density functional theory. The sensing material was fabricated, and the effect of reduction time shown improved the recovery of ammonia and toluene sensing at room temperature. Structural, morphological, and electrical characterizations were performed on both RG1 and RG3. The sensor response toward toluene vapor of 300 ppm was found to vary 4.4, 2.5, and 3.8% for RG1, RG2, and RG3, respectively. Though RG1 shows higher sensing response with poor recovery, RG3 exhibited complete desorption of toluene after the sensing process with response and recovery times of approximately 40 and 75 s, respectively. The complete recovery of toluene molecules on RG3 is due to the generation of new sites after the reduction of oxygen functionalities on its surface. It could be suggested that these sites provided anchor to ammonia and toluene molecules and good recovery under N 2 purge. Both theoretical and experimental studies revealed that tuning the oxygen functional groups on rGO could play a vital role in the detection of volatile organic compounds (VOCs) on rGO sheets and was discussed in detail. This study could provoke knowledge about rGO-based sensor dependency with oxygen functional groups and shed light on effective monitoring of VOCs under ambient conditions for air quality monitoring applications.

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Magnetite nanoparticles (Fe 3 O 4 ) decorated reduced graphene oxide (rGO) composite was synthesized by the solvothermal method and utilized as a potential adsorbent for the removal of cesium (Cs + ) and strontium (Sr 2+ ) ions from aqueous solution. The effects of adsorbate concentration and reaction time on the removal efficiencies of Cs + and Sr 2+ were investigated. The adsorption capacity increases as the initial concentration of Cs + /Sr 2+ increased from 1 to 170 mg/L, which might be due to the more available adsorption sites, and the adsorbent reached equilibrium at 360 min. The adsorption isotherm was fitted to the Freundlich model with maximum adsorption capacities of Cs + and Sr 2+ being 128.2 and 384.6 mg g −1 , respectively. The kinetic study showed that the adsorption behavior followed pseudo-second-order kinetics. The rGO/Fe 3 O 4 nanocomposite showed excellent selectivity toward Cs + and Sr 2+ even in the presence of competitive cations (Na + , K + , and Mg 2+ ) having a higher concentration.

Reduced graphene oxide is an excellent candidate for various electronic devices such as high performance gas sensors. In this work Graphene oxide was prepared by oxidizing graphite to form graphite oxide. From XRD analysis the peak around 11.5o confirmed that the oxygen was intercalated into graphite. By using hydrazine hydrate, the epoxy group in graphite oxide was reduced then the solution of reduced graphite oxide (rGO) is exfoliated. Raman spectrum of rGO contains both G band (1580 cm-1), D band (1350 cm-1). The remarkable structural changes reveals that reduction of graphene oxide from the values of ID/IG ratio that increase from 0.727 (GO) to 1.414 (rGO). The exfoliated reduced graphite oxide solution is spin coated on to the SiO2/Si substrates.