Synthesis And Photocatalytic Hydrogen Of A Series Of Titanium Oxo-clusters And Zirconium Metal Organic Frameworks

Polyoxometallates(POMs for short) have been studied for more than a century. The application fields. POMs has expanded their application fields from initial catalysis to the magnetic field, catalysis, chiral and biomimetic fields, nano materials and surface chemistry. Humans have been aware of exhaustion of global energy resources gradually and the necessity of development of new stable clean energy, researcher pay their attention to POMs which has excellent catalytic properties among inorganic compounds. IIB transition metal titanium and zirconium are suitable for dye-sensitized solar cell and photocatalyst for hydrogen evolution from splitting water, as their gab bands are about 2.0eV. The research of titanium oxo clusters have reached a plateau in developing new stuctures, thus researchers pay more attention to the photocatalytic properties of the known structures, extending their range of light absorption and increasing the efficiency of photocatalytic hydrogen production by function and optimization of the structure. However the reseach of zirconium oxo clusters and zirconium metal organic framework started later than that of titanium, and is in their ascent stage. Especially photocatalyst for hydrogen evolution from splitting water of them is relatively infrequent, which has been focused on by us. Here in our work, environmentally friendly alcohols were used instead of traditional toxic solvent for titanium oxo-clusters. Three titanium oxo-clusters, Ti6O4(OEt)4(OiPr)4[OOCC6H5]8(1), Ti6O4(OEt)8[OOC(CH3)3]8(2) and Ti6O4(OCH3)8[OOC(CH3)3]8(3) were prepared by the combination of titanium isopropoxide, different carboxylic acid under mild condition for a short period of time. All the compounds are crystallized in the same space group P21/c. Rearrangement of Ti atoms could been observed when compound 2 and 3 are heated in 100 °C for more than 24 hours, and their [Ti6O4] core turn to [Ti6O4] core which is more compact than before( Ti6O6(OEt)6[OOC(CH3)3]6 and Ti6O6(OCH3)6[OOC(CH3)3]6 for compound 2 and 3 respectively), while rearrangement of compound 1 can’t been seen although it is heated for more than 3 days steadily. Their similar structures and high activity in photocatalytic hydrogen from water under UV light have been investigated in detail. The highest rates of compound 1-3 are higher than ones under the same condition by pure nano TiO2. The discovery of these new titanium oxo-clusters affords new opportunities for developing metal oxo-clusters chemistry and exploring highly efficient photocatalysts. Moreover the rearrangement of compound 2 and 3 doesn’t impact on the high activity of photocatalyst for hydrogen evolution. Synthesis and photocatalyst for hydrogen evolution of zirconium oxo clusters and zirconium metal organic framework are under way at present.