Synthesis Of Binary Metal Sulfides And Selenides For Photocatalysis

Semiconductor photocatalysis as a green technology has attracted tremendous attention due to its promising potential application for solving serious environmental and energy problems.Exploring broad spectrum responsive photocatalysts remains a challenge for solar energy applications.Hexavalent Chromium(VI)as most common contaminant is highly toxic to most organisms.The photocatalytic reduction of Cr(VI)to Cr(III)is considered as an efficient route to remove Cr(VI).In this work,we report the design and fabrication of several binary metal sulfides and selenides for photocatalytic reduction of Cr(VI)in order to solve two key problems in this field such as the narrow light absorption region and quick recombination of photo-induced electron-hole pair.The concrete research content is as follows:1.ZnO-MoSe2 composites were successfully fabricated via a simple solvothermal method.Their photocatalytic activity in the reduction of Cr(VI)was inverstigated under visible light irradiation.The results show that the introduction of MoSe2 in Zn O can increase the light absorption,and inhibit the recombination of charge carreies,thus enhance the photocatalytic activity.When the weight ratio of MoSe2 to ZnO is 1:1,the composite achieves a highest Cr(VI)reduction rate of 100%,which should be attributed its comparatively higher light absorption,efficient charge separation and transfer as well as relatively large number of surface active sites.2.MoSe2-carbon quantum dots(COQs)composites were successfully synthesized via a simple solvothermal method.Their photocatalytic activity in the reduction of Cr(VI)was investigated under ultraviolet,visible and near-infrared light irradiation.The results show that the introduction of CQDs in Mo Se2 can increase the light absorption and inhibit the recomibination of charge carries,thus enhance the photocatalytic activity due to the light convertion of CQDs.The MoSe2-CQDs composite with 1wt.% CQDs achieves a highest Cr(VI)reduction rate of 99%,which makes the MoSe2 to a promising photocatalysts for the effective utilization of solar energy.3.Ni3S2-reduced graphene oxide(RGO)hybrid composites with sheet-on-sheet structure were synthesized by a facile microwave-assisted method for photocatalysis.The results show that the introduction of RGO in Ni3S2 can provide more active sites and inhibit the recombination of charge carries due to the integrative effect and good interfacial contact between Ni3S2 and RGO,thus enhance the photocatalytic activity.The Ni3S2-RGO composite with 1 wt.% RGO achieves a highest Cr(VI)reduction rate of 91%,which should be attributed its comparatively higher light absorption,efficient charge separation and transfer as well as relatively large number of surface active sites.4.CuS-RGO hybrid composites were synthesized by a facile microwave-assisted method.Their photocatalytic activity was investigated under ultraviolet and visible light irradiation.Results indicate that the introduction of RGO in CuS can inhibit the recombination of charge carreis due to the integrative effect and good interfacial contact,thus enhance the photocatalytic activity.The CuS-RGO composite with 1wt.% RGO achieves a highest Cr(VI)reduction rate of 99%,which should be attributed its comparatively higher light absorption,efficient charge separation and transfer as well as relatively large number of surface active sites.5.ZnS-RGO hybrid composites were synthesized by a facile microwave-assisted method.Their photocatalytic avtivity was investigated under ultraviolet and light irradiation.Rsults indicate that the introduction of RGO in ZnS can increase the light absorption and inhibit the recombination of charge carreis due to the integrative effect and good interfacial contact,thus enhance the photocatalytic activity.The ZnS-RGO composite with 1wt.% RGO achieves a highest Cr(VI)reduction rate of 100%,which should be attributed its comparatively higher light absorption,efficient charge separation and transfer as well as relatively large number of surface active sites.