Photocatalytic Performance Of Thiol-functionalized Zr-based MOF（UiO-66（SH）₂）and Its Composite Materials

Photocatalytic technology,driven by solar energy,can realize the energy conversion,but also effectively degrade the pollutants.However,traditional semiconductor photocatalysts show some defects,such as poor solar energy utilization and unclear mechanism.These limit the further application of photocatalytic technology seriously.The key for settling the above issues lies in the photocatalysts.MOFs are a class of porous coordination polymer with periodic three-dimensional network structure,assembled by transition metal and organic linkers.They have some outstanding properties including high specific surface area,structural adaptivity and flexibity.A lot of MOFs with the pseodo-semiconductor are a kind of potential excellent photocatalytic materials.Moreover,their unique structures are benefit for studying the reaction mechanism.This thesis focused on the development of the efficient MOFs photocatalysts with tunable band structures in respond to visible light.UiO-66(SH)2 was succesfully prepared by modifying the ligand in Zr-MOFs(UiO-66)with the introduction of thiol groups.The modulation of band structure and optical absorption property can be achieved at the molecular level for UiO-66.Moreover,taking the advantage of the unique features of thiol group,high suface area and porous structure for UiO-66(SH)2,we designed the M/UiO-66(SH)2(M = Au,Pd,Pt)composites photocatalysts in order to further improve the photocatalytic activities of UiO-66(SH)2.These studies may lay the acdemic and experiment foundation for the optimization and design of MOFs photocatalyts with highly effective performances.The details are summarized briefly as follows:(1)UiO-66(SH)2 was prepared via modification ligand with thiol groups and applied for photocatalytic selective oxidation of benzyl alcohol for the first time.XRD patterns indicated that UiO-66 and UiO-66(SH)2 had a same topology structure.FT-IR spectrum of UiO-66(SH)2 shows the existence of free thiol group.The photoabsorption edge could be shifted from ultraviolet region(320 nm)to visible light region(430 nm)by introducing the thiol group on the ligand.UiO-66(SH)2 shows excellent performances for photocatalytic selective oxidation of alcohols to aldehydes under visible-light irradiation(λ ≥ 420 nm).Moreover,the photocatalystic activities were dramatically affected by the reaction atmospheres.The effects were discussed according to quenching experiments and ESR analysis.(2)M/UiO-66(SH)2(M=Au,Pd,Pt)were successfully fabricated by an interation between thiol group and precious metals.M/UiO-66(SH)2(M=Au,Pd,Pt)effectively improved the photocatalytic conversion of alcohols to aldehydes,simultaneously maintaining the high selectivity.Especially,the conversion of benzyl alcohol over Pd/UiO-66(SH)2 reaches 73.7%.A probably mechanism was further proposed based the characterization results.