Preparation Of Cd_xMn_1-xS Photocatalysts And Their Performance Of Hydrogen Production

Sulfide solid solution photocatalyst becomes a hot topic due to its goodstability, small band gap, visible light response, and it can regulate the bandstructure by adjusting the composition. In order to improve the photocatalyticactivity of the solid solution photocatalyst as well as the response to the visibleregion of the solar spectrum, Cd_xMn_1-xS photocatalysts were prepared by thehydro-solvothermal method. The prepared photocatalysts were characterized byXRD, UV-Vis, XPS and SEM testing techniques. The effects of the value of x，preparation time and solvent on crystalline structure and photocatalytic activityof photocatalyst were researched. The band gaps of photocatalyst were deducedby UV-vis absorption spectra to study their performance of hydrogen production.The photocatalytic activity of catalyst was researched by the experiment of watersplitting for the production of hydrogen, investigating optical stability, theamount of photocatalyst and the concentration of electron donor influence onphotocatalytic activity.The results show that Cd_xMn_1-xS prepared with sodium sulfide exist in theform of solid solution and its spectral response of the photocatalysts is extendedto the visible region. The energy gap of Cd_0.52Mn_0.48S is2.27eV, which is thehighest hydrogen production rate of the prepared photocatalyst prepared withthiourea by the hydro-solvothermal method. Mn, Cd and S elements in theprepared photocatalysts present in the form of Mn2+, Cd2+and S2-separately. Thephotocatalytic activity of the solid solution Cd_xMn_1-xS photocatalyst prepared byhydro-solvothermal method for12h is better. When the Cd_xMn_1-xS is preparedwith component solvent of water and ethylenediamine, the release rate of S2-increase with increasing concentration of alkaline and the solid solution is easy tobe formed. The stability of photocatalyst is demonstrated by keeping the highphotocatalytic activity after the photocatalytic reaction for20h. The experiment result of producing H₂by photocatalytic splitting watershowed that the highest rate of hydrogen production with the preparedphotocatalyst Cd_0.52Mn_0.48S is305.7μmol·h^-1, which is prepared with thiourea asthe sulfur source and component solvent of water and ethylenediamine as thesolvent for12h, under the conditions of the amount of photocatalyst for0.3g,0.25mol/L Na₂SO₃and0.20mol/L Na₂S as electron donor.