Synthesis And Photocatalytic Performance Of Transition Metal Sulfides

Transition metal sulfides with3d valence electron shell structure have specialstructure and excellent physical&chemical properties, which is one of the mainresearches on the development of material science. So, transition metal sulfides arewidely used in industrial production, such as catalysis, lubrication equipment, batterymanufacturing, refractory material, and pigment, optical and magnetic devices and soon.There are a variety of methods to prepare transition metal sulfide, but we alwayscome across some problems in preparation of them, such as longer reaction time andspecial reaction devices, and so on. Another problem is that it is difficult to obtain thepure phase. In this paper, we obtained relatively pure single metal sulfide bysulfocarbamide-oxalic acid method. Oxalic acid was added to change crystallizationforms of materials; mineralizers were used in the reaction system to get the ideal crystal,and change the reorganization structure of the compound.On synthesis of Mn-S compound, we used sulfocarbamide as sulfur source, and gotMnS without adding oxalic acid, but we got MnS₂with oxalic acid; we got MnS whenthere was no mineralizer or only a little, but we got MnS₂oppositely; MnS can be gettenwhen more dosage of sulfocarbamide was added, and so it was thioacetamide.On synthesis of Ni-S compound, we got NiS₂without oxalic acid, but we got NiSwith oxalic acid; we got millerite NiS without mineralizer, but millerite NiS and NiSmixed phases were getten oppositely; millerite NiS can be obtained with less dosage ofsulfocarbamide, but two-phase of NiS appeared oppositely, when we changed thedosage of thioacetamide we also got NiS pure phase.On synthesis of Cu-S compound, we got covellite CuS without oxalic acid, andwhen the dosage of sulfocarbamide was increasing, the product was changed from CuSto Cu₉S₅, and then Cu2S appeared; when the dosage of sulfocarbamide was increasing inthe exist of mineralizer,, the product was changed from CuS to Cu₉S₅, and then Cu2Sappeared,but it was changed from Cu₉S₅to CuS, and then Cu2S without mineralizer;when we increased the dosage of sulfocarbamide and thioacetamide, the product waschanged from CuS to Cu₉S₅, and then Cu2S.On synthesis of Fe-S compound, we got pyrite FeS₂without oxalic acid, but troiliteFeS can be getten with oxalic acid; we got FeS without mineralizer, but FeS₂was obtained by changing the dosage of mineralizer without oxalic acid; we also got FeS bychanging the dosage of sulfocarbamide, when we added less thioacetamide we obtainedFe3S4, but pure FeS appeared oppositely.On synthesis of Co-S compound, we got cattierite CoS₂without oxalic acid, but wegot CoS on the other hand; we got CoS with mineralizer, but we got Co₉S₈、CoS whenwe added mineralizer; CoS can be obtained by changing the dosage of sulfocarbamide,but too low or high of which will not conducive to the formation of CoS; pure Co₉S₈can also be obtained by changing the dosage of thioacetamide.Then we studied uv-photocatalytic performances of the transition metal sulfide.MnS₂、Cu₉S₅、MnS almost have no photocatalytic activity to the decolorization ofmethylene blue, but NiS、Co₉S₈、FeS₂、NiS₂、CoS₂、FeS、CuS have photocatalyticdegradation active of methylene blue, after uv light irradiation for1h, the decolorizationrate was34.41%、39.81%、42.36%、51.65%、52.08%、58.11%、65.14%, separately.On reduction to nitrate with transition metal sulfide, we found that CuS、FeS₂、NiS₂、NiS、MnS₂、MnS、CoS、FeS、Cu₉S₅、CoS₂have uv-photocatalytic activity on nitratereduction, after uv light irradiation for1hour, the conversion rate of nitrate were2.37%、4.56%、11.81%、12.87%、18.60%、21.34%、22.84%、30.41%、35.57%、43.86%, and the ability of which for the reduction of nitrate increases.