【作者】 马刚峰；

【导师】 李越湘；

【作者基本信息】 南昌大学 ， 物理化学， 2008， 硕士

【摘要】 氢气是未来最理想的能源,太阳能取之不尽,用之不竭,利用太阳能光解水制氢是制氢最理想的方法。本论文研究了B,N共掺杂TiO₂,碱式氧硫锌固溶体(ZnO_xS_1-x-0.5y（OH）_y)的制备及其可见光光催化制氢性能,研究内容分为两个部分:一、硼、氮共掺杂TiO₂光催化剂的制备及其可见光光解水制氢性能研究。以钛酸四正丁酯,尿素,硼酸为前躯体,采用溶胶-凝胶法制备了B,N共掺杂TiO₂可见光催化剂,通过可见光光还原原位沉积法载铂,以EDTA-2Na为电子给体,考察了催化剂在可见光（λ＞420nm）下制氢活性。通过UV-Vis DRS,XRD,FT-IR,XPS,BET比表面,电化学等手段对催化剂进行了表征。实验结果表明,N掺杂可在TiO₂中形成N-Ti-O键,使其具有可见光吸收能力;B主要存在于催化剂表面,但部分掺入TiO₂晶格中。B掺杂显著地提高了N-TiO₂的可见光活性。相对于纯TiO₂和N-TiO₂,B,N共掺杂TiO₂的粒径更小,光电流更大,表面羟基含量更多,晶格畸变增加,而且掺入的B可以作为电子的浅势捕获阱,延长光生电子和空穴的寿命,因而提高了催化剂的活性。二、碱式氧硫锌固溶体(ZnO_xS_1-x-0.5y（OH）_y)的制备及其可见光分解水制氢性能研究。以硝酸锌,硫化钠,氢氧化钠为原料,采用简单的共沉淀方法制备碱式氧硫锌固溶体(ZnO_xS_1-x-0.5y（OH）_y),经焙烧后得到可见光催化剂.。以Na₂S和Na₂SO₃为电子给体,考察了催化剂在可见光（λ＞420nm）下制氢活性。通过UV-Vis DRS,XRD,TG-DTA,BET比表面,电化学等手段对催化剂进行了表征。实验结果表明,催化剂的组成和沉淀温对制氢活性有很大影响。度低温沉淀时形成ZnS_1-x（OH）_2x固溶体,高温沉淀和焙烧后,催化剂都会有不同程度的脱溶,产生ZnO,并且O溶于ZnS形成碱式固溶体ZnO_xS_1-x-0.5y（OH）_y。氢氧基团（-OH）对形成固溶体及催化活性都有贡献,催化剂的活性成分是ZnO_xS_1-x-0.5y（OH）_y。当ZnO与ZnS物质的量的比为1:1,373 K沉淀,673 K N₂气氛中焙烧制备的催化剂活性最好,不负载贵金属,可见光照射下,量子效率可达到2.9%。更多还原

【Abstract】 Hydrogen is considered as an ideal energy carrier in the future.Because solar energy is inexhaustible,photocatalytic water splitting by solar energy has been considered as one of the ideal hydrogen production processes.In this thesis,we studied the preparation and the photocatalytic activity of B-N-codoped TiO₂,basic Zincoxysulfide(ZnO_xS_1-x-0.5y（OH）_y) solid solutions for hydrogen evolution.The research work is composed of two parts:1.Boron and nitrogen co-doped titania with enhanced visible-light photocatalytic activity for hydrogen evolution.A visible-light boron and nitrogen co-doped titania （B-N-TiO₂） photocatalyst was prepared by sol-gel method with titanium tetra-n-butyl oxide,urea and boric acid as precursors.Photocatalytic activity for hydrogen production from aqueous solution containing sacrificial reagents,EDTA-2Na,over platinized B-N-TiO₂ under visible light（λ＞420 nm） irradiation was investigated.Pt was deposited on B-N-TiO₂ in situ by photochemical deposition under visible light irradiation.The photocatalyst was characterized by Fourier Transform Infrared （FT-IR）,UV-Vis diffusive reflectance spectroscopy（DRS）,X-ray photoelectron spectroscopy（XPS）,X-ray diffraction（XRD） and BET specific surface area, Electrochemistry method.In nitrogen doped titania（N-TiO₂） N-Ti-O bond is formed, which extends the absorption edge to the visible light region.A part of doping boron enters into titania lattice and most of the boron exists at the surface of the catalyst. Compared B-N-TiO₂ with N-TiO₂,the crystallite size of the former decreases,the photocurrent increases,and the content of the surface hydroxyl group increases. Furthermore,doping boron could act as shallow traps for photoinduced electrons to prolong the life of the electrons and holes.Therefore,the visible light activity of B-N-TiO₂ increases greatly compared with that of N-TiO₂.2.Photocatalytic H₂ evolution under visible-light irradiation over basic Zincoxysulfide(ZnO_xS_1-x-0.5y（OH）_y) solid solution was investigated.The ZnO_xS_1-x.0.5y（OH）_y solid solution showed photocatalytic activities for H₂ evolution from aqueous solution containing sacrificial reagents,SO₃^2- and S^2-,under visible-light（λ＞420 nm） irradiation without cocatalyst.The photocatalysts were prepared by general coprecipitation method using Zn（NO₃）₂·6H₂O,Na₂S·9H₂O and NaOH.The photocatalyst was characterized by UV-Vis diffusive reflectance spectroscopy（DRS）,X-ray diffraction（XRD）,BET specific surface area,Differential Thermal Analysis-Thermogravimetry（DTA-TG） and Electrochemistry method.The composition and coprecipitation temperature greatly influenced the activity of the photocatalysts for hydrogen production.At low coprecipitation temperature, ZnS_1-x（OH）_2x solid solution was formed,whereas at high coprecipitation temperature or after calcination,a part of ZnO separated out from ZnS_1-x（OH）_2x solid solution.At higher calcination temperature,basic Zincoxysulfide(ZnO_xS_1-x-0.5y（OH）_y) solid solution decomposed completely to form ZnO and ZnS.Hydroxide groups（-OH） played a major role in forming solid solution and photocatalytic activity.The active component of the photocatalysts was ZnO_xS_1-x-0.5y（OH）_y.The optimized photocatalyst, with a molar composition of ZnS to ZnO 1:1,coprecipitated at 373 K and calcined at 673 K under N₂ atmosphere,exhibited an apparent quantum yield of ca.2.9%at visible-light irradiation without loaded noble metal.更多还原