The role of sodium dodecyl sulfate mediated hydrothermal synthesis of MoS2 nanosheets for photocatalytic dye degradation and dye-sensitized solar cell application.

The novel properties and exciting behavior of two-dimensional nanosheet-based materials have piqued the interest of research all over the world. In this study, bulk molybdenum disulfide (bulk MoS2) and sodium dodecyl sulfate-mediated molybdenum disulfide nanosheets (MoS2-SDS NS) were synthesized via a facile sonication and hydrothermal process. The findings from the characterization revealed that the addition of sodium dodecyl sulfate (SDS) surfactant reduces the crystal phase and changes the structural morphology of bulk MoS2. Furthermore, the photocatalytic and photovoltaic performance of bulk MoS2 and MoS2-SDS NS were also investigated. The results show that by using methylene blue dye, the photocatalytic efficiency increased from 56.30% to 91.84% at 150 min under UV-Visible light irradiation, and the photo-conversion efficiency (PEC (%)) of the dye-sensitized solar cell increased from 1.47% to 3.81% for bulk MoS2 and MoS2-SDS NS, respectively. Finally, we discussed in-depth the effect of SDS surfactants on MoS2, which can improve their photovoltaic and photocatalytic performance.

Synthesis and Characterization of Fe0.8Mn0.2Fe2O4 Ferrite Nanoparticle with High Saturation Magnetization via the Surfactant Assisted Co-Precipitation.

Manganese ferrite nanoparticles (MnFe2O4) were synthesized via surfactant-assisted co-precipitation, where sodium dodecyl sulfate (SDS) was used as the template to control particle size at various SDS concentrations. The substitutions of iron (II) (Fe2+) into the MnFe2O4 ferrite nanoparticles were carried out to obtain Fe(1-x)MnxFe2O4, with various Mn2+: Fe2+ molar ratios. The synthesized ferrite nanoparticles were characterized by the Fourier-transform infrared spectroscopy (FT-IR), thermogravimetric analyzer (TGA), X-ray diffractometer (XRD), energy dispersive X-ray (EDX), X-ray photoelectron spectroscopy (XPS), scanning electron microscope (SEM), transmission electron microscope (TEM), two-point probe, and vibrating sample magnetometer (VSM) techniques. The experimental Mn:Fe mole ratios of the Fe(1-x)MnxFe2O4 ferrite nanoparticles were verified to be in agreement with the theoretical values. The synthesized MnFe2O4 and Fe(1-x)MnxFe2O4 ferrite nanoparticles were of mixed spinel structures, with average spherical particle sizes between 17-22 nm, whereas the magnetite ferrite nanoparticles (Fe3O4) were of the inverse spinel structure. They showed soft ferromagnetic behavior. The synthesized Fe0.8Mn0.2Fe2O4 ferrite nanoparticle possessed the highest saturation magnetization of 88 emu/g relative to previously reported work to date.

Optimisation of purification techniques for the preparation of large-volume aqueous solar nanoparticle inks for organic photovoltaics.

In this study we have optimised the preparation conditions for large-volume nanoparticle inks, based on poly(3-hexylthiophene) (P3HT):indene-C60 multiadducts (ICxA), through two purification processes: centrifugal and crossflow ultrafiltration. The impact of purification is twofold: firstly, removal of excess sodium dodecyl sulfate (SDS) surfactant from the ink and, secondly, concentration of the photoactive components in the ink. The removal of SDS was studied in detail both by a UV-vis spectroscopy-based method and by surface tension measurements of the nanoparticle ink filtrate; revealing that centrifugal ultrafiltration removed SDS at a higher rate than crossflow ultrafiltration even though a similar filter was applied in both cases (10,000 Da Mw cut-off). The influence of SDS concentration on the aqueous solar nanoparticle (ASNP) inks was investigated by monitoring the surface morphology/topography of the ASNP films using atomic force microscopy (AFM) and scanning electron microscopy (SEM) and photovoltaic device performance as a function of ultrafiltration (decreasing SDS content). The surface morphology/topography showed, as expected, a decreased number of SDS crystallites on the surface of the ASNP film with increased ultrafiltration steps. The device performance revealed distinct peaks in efficiency with ultrafiltration: centrifuge purified inks reached a maximum efficiency at a dilution factor of 7.8 × 104, while crossflow purified inks did not reach a maximum efficiency until a dilution factor of 6.1 × 109. This difference was ascribed to the different wetting properties of the prepared inks and was further corroborated by surface tension measurements of the ASNP inks which revealed that the peak efficiencies for both methods occurred for similar surface tension values of 48.1 and 48.8 mN m-1. This work demonstrates that addressing the surface tension of large-volume ASNP inks is key to the reproducible fabrication of nanoparticle photovoltaic devices.