表面结构可调控的α-Fe_2O_3薄膜的制备及光电化学活性研究

Preparation and Photoelectrochemical Activities of α-Fe_2O_3 Films with Adjustable Surface Structures

空穴界面传递阻力过大是影响α-Fe2O3薄膜光电催化活性的主要原因之一,本文旨在探讨通过调控薄膜表面纳米结构从而优化空穴界面传递动力学的可能性.基于简单的电化学沉积路线,制备了表面纳米结构可调控的α-Fe2O3薄膜.采用原子力显微镜(AFM)、扫描电子显微镜(SEM)、X射线粉末衍射(XRD),紫外可见漫反射光谱(UV-vis DRS)分别研究薄膜样品的形貌、结构和光吸收性能;采用斩光计时电流(I-t)、循环伏安法(CV)、电化学阻抗谱(EIS),开路光电压演变(Voc)等光电化学测试技术对影响样品光活性的因素进行研究.结果表明,有尖锐突起纳米结构的表面相比于平坦表面更加利于空穴的界面传递,从而减弱了由于空穴积累而导致的复合加剧问题.

The large hole-interface-transfer resistance is one of the main factors greatly influencing the performance of Fe2O3 photoelectrodes for photoelectrochemical reactions. The aim of this work is to explore the possibility of optimizing the kinetics of hole interface transfer by controlling over the surface nanostructures. α-Fe2O3 films with adjustable surface structures are prepared through a simple electrochemical deposition process. Atom force microscope（ AFM）,scanning electron microscope（ SEM）,powder X-ray diffraction（ XRD）,and UV-visible diffusion reflection（ UVDR） techniques are used to characterize respectively the surface morphology,structure and photo absorption ability of the films. A series of electrochemical methods including chronoamperometry（ I- t）,cyclic voltammetry（ CV）,electrochemical impedance（ EIS）,and open-circuit photovoltage（ Voc） transient are applied to study the influence mechanisms of film structures on photoactivity. Our research indicates that the sharp nanocone surface structure transfers hole more efficiently than the flat surface structure does,and hole-accumulation induced recombination can be greatly reduced.