Preparation And Optical And Catalytic Properties Of Transition Metal Nanocrystalline Sulfide

Transition metal sulfides are generally considered to be potential candidates for visible light response photocatalysis.The valence band of transition metal sulfides is usually composed of 3p orbitals.Compared with transition metal oxides,it produces more negative valence bands and narrow band gaps.The main contents of this paper are as follows:?1?MoS₂/SrZrO₃ heterojunction nano-photocatalysts were prepared by two-step hydrothermal reaction.The addition of 0.05 wt%MoS₂ onto the surface of SrZrO₃ can produce hydrogen up to 5.31 mmol H₂ under UV irradiation,and the mechanism of H₂transformation is also studied.It is found that the load of MoS₂ plays an important role in the photocatalytic activity,and the role of MoS₂ in the MoS₂/SrZrO₃ photocatalyst is matched with the energy band,which inhibits the recombination of photoelectrons and holes,which leads to the enhancement of H₂ production.?2?A simple two-step hydrothermal synthesis of MoS₂/SrTiO₃ composite materials can be used for degradation of methyl orange organic dyes under UV irradiation.The photocatalytic degradation rate of the MoS₂/SrTiO₃ composite photocatalyst in 60minutes,with a content of 99.95 wt%SrTiO₃ and 0.05 wt%MoS₂,was 99.81%,which was significantly higher than that of pure SrTiO₃.In addition,the proper load of MoS₂is very important for optimizing the photocatalytic properties of MoS₂/SrTiO₃composites.This is due to the excessive loading of MoS₂ to screen the active sites,and also to reduce the intensity of ultraviolet radiation.?3?Bi₂WO₆/SrTiO₃ composites were prepared by two-step hydrothermal method,and the structural and physical properties were analyzed by XRD,TEM,SEM,XPS,DRS,BET and PL.The heterostructure between SrTiO₃ and Bi₂WO₆ plays an important role in improving the photocatalytic degradation of rhodamine B?RhB?.8 wt%SrTiO₃/Bi₂WO₆ is the best choice in the prepared catalysts(D=98.4%and k=0.0463min^-1).?4?A new AgI/Bi₂MoO₆ nanostructures were prepared by deposition precipitation method,and their photocatalytic activity and stability for visible light degradation of RhB were further studied.The results showed that the photocatalytic degradation of RhB by Bi₂MoO₆ or AgI alone showed poor activity,but the nano heterostructure had excellent properties.The optimum proportion of AgI/Bi₂MoO₆ composites is AgI containing 20 wt%,which shows the highest photocatalytic degradation rate.RhB is completely degraded in 75 min under visible light.In addition,the composite photocatalyst has shown considerable stability in several recycling applications.By analyzing the band structure and photocatalytic active species,we explored a possible mechanism for enhancing the photocatalytic activity of AgI/Bi₂MoO₆ composites.This enhancement is attributed to the matching of energy bands between AgI and Bi₂MoO₆,which greatly inhibits the recombination of photogenerated electrons and holes.