Modification Of TiO₂,ZnO And Their Performance Of Photocatalytic Hydrogen Evolution Under Visible Light

In this thesis,the modification of TiO₂,ZnO and their performance of photocatalytic hydrogen evolution under visible light irradiation was researched.The research work is composed of two parts;The first part is that preparation of beryllium-nitrogen-codoped TiO₂ and performance of photocatalytic hydrogen evolution under visible light irradiation.The nitrogen doping TiO₂(N-TiO₂)was prepared by the calcinations of hydrolysis product of titanium sulphate with aqueous ammonia.Using the N-TiO₂ and BeSO₄ solution, Be-N-co-doped TiO₂ was prepared by impregnation method.Pt was deposited on Be-N-TiO₂ by photochemical deposition under visible light irradiation.Using EDTA as an electron donor,the activities of catalysts were evaluated by photocatalytic hydrogen production under visible light(λ=420nm).The nitrogen doping TiO₂ (N-TiO₂)has strong absorption in visible region and activity for hydrogen evolution under visible light irradiation; Be-N-co-doped TiO₂ further enhances the activity compared to N-TiO₂.When calcinated temperature is 300℃,the Pt/N-TiO₂ and Pt/Be-N-TiO₂ have the highest activity for evolution of H₂ under visible light respectively,namely 5.3μmol/3h and11.2μmol/3h respectively.X-ray diffraction, Raman spectrum,UV-Vis diffuse reflectance spectroscopy,and Fourier transform infrared spectroscopy were used to characterize the catalyst samples.The results showed that the N-Ti-O bond formed in the catalyst could extend the absorption edge to the visible light region.Due to Be²⁺doping,the separation of photoinduced electron-hole pairs can be effectively promoted and the oxygen vacancy produced by nitrogen doping can be removed,and thus the evolved H2 activity is improved compared to N-TiO₂.The second part is that preparation of Eosin-Y sensitized ZnO and performance of photocatalytic hydrogen evolution under visible light irradiation.Using M/ZnO (Eosin-Y-M-ZnO,M=Pt,Ru,Cu,Ag)and Eosin-Y solution,Eosin-Y sensitized M /ZnO was prepared by impregnation method.Using triethanolamine(TEOA)as an electron donor,the activities of Eosin-Y sensitized Pt/ZnO catalyst under visible light (λ=420nm)were evaluated by photocatalytic hydrogen production.Fourier transform infrared spectroscopy,UV-Vis diffuse reflectance spectroscopy were used to characterize the catalyst samples.The effect of concentration of Eosin-Y,loading different noble metal and the amount of noble metal loaded on the activities of the prepared catalysts were investigated.The experimental results are as follows.Because there are different adsorption amounts for dye on catalysts in the various concentration of Eosin-Y when reaching adsorption equilibrium,the catalysts have different activities of hydrogen evolution.When loading the same amount of noble metal M(M=Pt,Ru,Cu,Ag),the order of activity is Ru＞Pt＞Cu＞Ag＞no metal loaded,because noble metal loaded increases adsorption amount of Eosin-Y,and different noble metal have different adsorption capacity of Eosin-Y.The activities of hydrogen evolution increased with increase of amount of noble metal Pt loading.The reason is that the number of adsorbed Eosin-Y increased with increase of noble metal Pt loading significantly.More metal loading enhances the electron transfer and hydrogen evolution in photocatalytic reaction.