The effects of different surfactants on the morphologies and electrochemical properties of MoS2/reduce graphene oxide composites

Ultrafine metal-organic framework @ graphitic carbon with MoS2-CNTs nanocomposites as carbon-based electrochemical sensor for ultrasensitive detection of catechin in beverages

GO/Co-MOF/PPy-350 (GPC-350) was synthesized by in situ growth of ultrafine Co-MOF on graphene oxide (GO), followed by encapsulation with polypyrrole (PPy) and calcination at 350.0℃. Meanwhile, MoS2-MWCNTs (MoS2-CNTs) were produced via the in situ synthesis of MoS2 within multi-walled carbon nanotubes (MWCNTs). The electrochemically superior GPC-350/MoS2-CNTs nanocomposite was then achieved by combining GPC-350 with MoS2-CNTs. The polypyrrole encapsulation serves to protect the ultrafine Co-MOF, preventing its degradation during the calcination process. The linear detection range of the GPC-350/MoS2-CNTs/GCE sensor for the determination of catechin (CA) in phosphate buffered saline (PBS) was from 5.0 to 1800.0 nM with a limit of detection of 1.78 nM. In addition, the materials were characterized using SEM, EDX, TEM, XRD, EIS, XPS, FTIR, and Raman. These results indicate that the synthesis of GPC-350/MoS2-CNTs nanocomposites is successful and CA in beverages samples can be effectively detected using electrochemical sensors. Additionally, the reaction mechanism of CA was explored through cyclic voltammetry. The application of GPC-350/MoS2-CNTs nanocomposites in sensor technology offers innovative approaches for the ultrasensitive detection of flavonoids.

CTAB Enhanced Room-Temperature Detection of NO2 Based on MoS2-Reduced Graphene Oxide Nanohybrid

A new NO2 nanohybrid of a gas sensor (CTAB-MoS2/rGO) was constructed for sensitive room-temperature detection of NO2 by 3D molybdenum disulfide (MoS2) and reduced graphene oxide (rGO), assisted with hexadecyl trimethyl ammonium bromide (CTAB). In comparison with MoS2 and MoS2/rGO, the BET and SEM characterization results depicted the three-dimensional structure of the CTAB-MoS2/rGO nanohybrid, which possessed a larger specific surface area to provide more active reaction sites to boost its gas-sensing performance. Observations of the gas-sensing properties indicated that the CTAB-MoS2/rGO sensor performed a high response of 45.5% for 17.5 ppm NO2, a remarkable selectivity of NO2, an ultra-low detection limit of 26.55 ppb and long-term stability for a 30-day measurement. In addition, the response obtained for the CTAB-MoS2/rGO sensor was about two to four times that obtained for the MoS2/rGO sensor and the MoS2 sensor toward 8 ppm NO2, which correlated with the heterojunction between MoS2 and rGO, and the improvement in surface area and conductivity correlated with the introduction of CTAB and rGO. The excellent performance of the CTAB-MoS2/rGO sensor further suggested the advantage of CTAB in assisting a reliable detection of trace NO2 and an alternative method for highly efficiently detecting NO2 in the environment.

Insights into the Influence of Key Preparation Parameters on the Performance of MoS2/Graphene Oxide Composites as Active Materials in Supercapacitors

Advances in energy storage and energy conversion play an essential role nowadays because the energy demands are becoming greater than ever. To overcome the actual performances of the materials used to build supercapacitors, a combination of transition metal dichalcogenides (TMDCs) and graphene oxide (GO) or reduced graphene oxide (rGO) as graphene-based structures are often studied for their excellent properties, such as high specific area and good electrical conductivity. Nevertheless, synthesis pathways and parameters play key roles in obtaining better materials as components for supercapacitors with higher technical performances. Driven by the desire to understand the influence of the structural and morphological particularities on the performances of supercapacitors based on MoS2/graphene oxide (GO) composites, a survey of the literature was performed by pointing out the alterations induced by different synthesis pathways and key parameters to the above-mentioned particularities.

Highly efficient removal of Cr(VI) from water based on graphene oxide incorporated flower-like MoS2 nanocomposite prepared in situ hydrothermal synthesis

An efficient adsorbent for the treatment of Cr(VI) was simply fabricated by combining graphene oxide with MoS₂ nanosheets via in situ hydrothermal process with CTAB as the surfactant. The experimental results indicated that the agglomeration of the MoS₂ nanosheets are reduced and uniformly grown on the graphene sheet during the in situ hydrothermal process, and the introduction of graphene oxide provided higher specific surface area and abundant oxygenic groups. Based on this, the removal efficiency of Cr(VI) onto MoS₂/rGO was 75.9% at pH 2.0, which was higher than that of bulk MoS₂ (61.0%). On account of Sips adsorption isotherm model, the highest uptake capacity of MoS₂/rGO toward Cr(VI) reached 80.8 mg g^-1. The adsorption kinetic consequences showed that the chemisorption process was the control step, and the removal mechanism for Cr(VI) is redox and adsorption; in this way, the adsorbed Cr(VI) was partially reduced to Cr(III). Furthermore, this as-prepared adsorbent also presented satisfying reusability for removal of Cr(VI) and can be used for the selective removal of Cr(VI) in the presence of NO₃^-. In short, it may provide a potential route to enhance the adsorption property of MoS₂ toward heavy metals through incorporating with GO, which would expand the applications of MoS₂ in the field of treatment of the heavy metal wastewater.