Study On Photocatalytic Hydrogen Production Of H 2 S By Composite Metal Sulfide Semiconductors

Metal sulphide,a class of important inorganic semiconductor material,has great application prospects in photocatalysis field due to its proper energy band structure.In this study,we mainly focused on two important aspects,the construction of H₂S decomposition device and the optimization of suitable photocatalyst for decomposing H₂S.Firstly,a complete system which was applied for the absorption and decomposition of H₂S as well as the as recovery of the as-obtained products,was constructed to decompose H₂S via photocatalytic reaction.The manganese sulfide?MnS?was chosen as photocatalyst for converting H₂S into H2.The cubic a-MnS with cubic morphology and hexagonal y-MnS with rod-like morphology were successfully prepared by a one-pot solvothermal method.Here,to evaluate the photocatalytic performances of MnS with different crystal phases,the tests that splitting H₂S into H2 catalyzed in Na2S/Na2SO3 solution under visible light??>420 nm?and full spectrum irradiation.The results revealed that a maximum H2 production rate of 2272.69?mol·g^-1·h^-1 can be achieved by the y-MnS under full spectrum irradiation.Meanwhile,the photoelectrical property of such two MnS phases was studied to explore the difference in photocatalytic activity.The results illustrated that the crystal structure was the essential reason for the difference of ?,?-MnS photocatalytic activity.Then,to enhance the photocatalytic activity of MnS,In₂S₃ with visible-light response was composited.The photocatalytic H2 evolution over all the samples was tested under visible-light irradiation??>420 nm?.The results showed that the MnS/In₂S₃ composite were excellent active for visible-light photocatalytic H2 production from H₂S.A maximum H2 production rate of 8360 ?mol·g^-1 ·h^-1 was achieved over MnS/In₂S₃₀.7 catalyst,which is of approximately 2090 times higher than that of the bare ?-MnS and 50 times higher than that of the ?-In₂S₃ alone.The corresponding apparent quantum yield of this sample is as high as 34.2%at 450 nm,the corresponding H2 evolution amount was of 36440 ?mol h^-1.Moreover,in order to explore the optimal conditions,the different H₂S with varied concentration and the different reaction medias were investigated for the photocatalytic experiment.The results demonstrated that the Na2S/Na2SO3 solution and the 3M H₂S were the optimal reaction media for the best hydrogen production performance.Finally,in order to further enhance visible-light photocatalytic H2 production activity of MnS/In₂S₃,MnS/In₂S₃/CuS composite was prepared through solvothermal treatment.According to the UV-vis diffusion reflection spectra,the introduction of Cu can dramatically increase the visible light absorption of the composite and as a result,the sample of MIC 1.2 presents the best absorption ability.Moreover,the hydrogen evolution rate of this sample is of about 29252 ?mol·g^-1·h^-1,which is 3,5 times higher than that of MnS/In₂S₃₀.7.Therefore,the addition of CuS can effectively increase the photocatalytic activity for splitting H₂S into H2.