肖特基异质结Pt/Bi_(4)O_(5)Br_(2)的制备及其光催化性能研究

Preparation of Schottky heterojunction Pt/Bi_(4)O_(5)Br_(2) and its photocatalytic performance

以Bi_(4)O_(5)Br_(2)为前驱体,通过静电吸附辅助光还原法成功制备了低负载量(0.05%~0.50%,质量分数)且高分散Pt纳米粒子修饰Bi_(4)O_(5)Br_(2)光催化剂体系.对一系列Pt/Bi_(4)O_(5)Br_(2)样品进行了降解双酚A(BPA)活性测试,结果表明,0.20%Pt/Bi_(4)O_(5)Br_(2)样品在模拟太阳光照射30 min对BPA的降解效率达96%,远高于单一Bi_(4)O_(5)Br_(2).通过一系列表征手段(XRD,SEM,TEM,XPS,UV-vis DRS,PL等)对催化剂的结构形貌、化学组分及光学性质进行了系统性研究.研究发现,0.20%Pt/Bi_(4)O_(5)Br_(2)复合物活性显著提高的主要原因归因于以下几点:第一,Pt作为电子捕获陷阱提高了光生电子-空穴的分离效率;第二,贵金属等离子共振效应提高其光利用效率;第三,Pt与Bi_(4)O_(5)Br_(2)构成肖特基异质结,提高了光生载流子利用率.此外,根据捕获剂实验证明光催化过程中主要的活性物种是h^(+)和·OH,并提出相应的反应机理,该结果为低含量贵金属修饰铋基材料提供一定的理论基础和指导意义.

Bi_(4)O_(5)Br_(2)photocatalyst modified by Pt nanoparticles with low loading content(0.05%-0.50%,mass fraction)and high dispersity was successfully synthesized by electrostatic adsorption-assisted photoreduction method(Bi_(4)O_(5)Br_(2)as precursor).The photocatalytic performance of samples was evaluated for the photocatalytic degradation activity of bisphenol A(BPA),the results showed that the degradation efficiency of BPA over 0.20%Pt/Bi_(4)O_(5)Br_(2)sample reached 96%(under simulated sunlight irradiation for 30 minutes),which was much higher than that of pure Bi_(4)O_(5)Br_(2).The structure,morphology,chemical composition and optical properties of the catalysts were systematically studied by a series of characterization methods(XRD,SEM,TEM,XPS,UV-vis DRS,PL,etc.).The characterization results proved that the photocatalytic activity of 0.20%Pt/Bi_(4)O_(5)Br_(2)composite significantly enhanced due to the following three points:firstly,Pt as an electron trapping trap improved the separation efficiency of photogenerated electron-hole pairs.Secondly,the plasma resonance effect of noble metal improved the light utilization efficiency.Finally,the formation of Schottky-heterojunction between Pt and Bi_(4)O_(5)Br_(2)improved the utilization efficiency of photoinduced charge.Furthermore,according to the trapping agent experiment,the main active species in the photocatalytic process were h^(+)and·OH,and the corresponding reaction mechanism was proposed so as to provide a certain theoretical basis and guidance for the low content noble metal modified Bi-based materials.