Reverse-microemulsion Synthesis Of Nano-sized Metal Sulfides

Transition metal sulfides such as CuS, MoS₂and WS₂with appropriate band-gap energy,high light absorption coefficient and good chemical stability, have drawn remarkable interestin photocatalytic hydrogen production because they are proved to be promising candidates forPt, a co-catalyst. Crystal phase, size and especially crystal-preferred growth of the nanosizedsulfides will exhibit a significant effect on improving the efficiency of electron-hole transportand photoctalytic activity. This thesis focuses on the controlled preparation of nanosizedmetal sulfides with unique shape via a W/O reverse microemulsion technique. The results aresummarized as follows:1. Two W/O reverse systems such as cetyl trimethyl ammonium bromide （CATB）/n-butanol/toluene/water and TX-100/cyclohexane/hexanol/water W/O reverse microemul-sion system have been successfully prepared at room temperature.2. Agaric-like CuS nanosheets was successfully synthesized by a CTAB/toluene/n-butanol/water W/O reverse microemulsion in the presence of copper acetate for a Cu source andThioacetamide as a sulfur source. The reports on the synthesis of CuS with Agaric-likeCuS nanosheets to date remain very limited. The as-synthesized CuS nanosheets showstrong absorption at about256nm in UV region, and exhibit a significant blue-shiftrelative to that of bulk CuS. This reveals that the as-obtained agaric-like has obviousquantum confinement effects. In addition, the influence of synthetic parameters such aswater/oil ratio （ω0）, aging time, the concentration of precursors and heat treatment on theformation of CuS nanostructues was investigated.3. Nanosized MoS₂partices with a mean diameter of25⁴0nm have been prepared by aCTAB/toluene/n-butanol/water W/O reverse microemulsion solution by choosingammonium tetrathiomolybdate as a precursor of Mo and hydroxylamine hydrochloride asreducing agent. The as-synthesized MoS₂nanoparticles exibit strong absorption at260nm.A large blue-shift of the absorption edge was observed compared with that of bulk2H-MoS₂（1040nm）, indicating the obtained MoS₂nanoparticles exhibit apparent quantum effect.4. Similarly, nanosized WS₂was prepared in TX-100/cyclohexane/hexanol/water W/Oquartery micelle solution in the presence of （NH4）2WS4as a precursor of W andNH2OH·HCl as a reducing agent.