柠檬酸对聚合物前驱体法制备WO_3薄膜光电性质的影响

Influence of citric acid on photoelectrochemical properties of WO_3 films obtained by polymeric precursor method

以偏钨酸铵为钨源,柠檬酸为络合剂,聚乙二醇(PEG)为聚合物合成前驱体溶胶,并用浸渍提拉法在FTO导电玻璃上制备了WO3薄膜,研究配位剂柠檬酸对聚合物前驱体法制备WO3薄膜结构和光电性质的影响。采用X线衍射、拉曼光谱和场发射扫描电镜等手段研究薄膜的相组成及表面形貌,借助标准三电极体系进行了光电化学测试,并进一步讨论了柠檬酸对WO3薄膜光电性能影响机理。结果表明:CA和W摩尔比为0,0.5,1.0和2.0条件下薄膜表面颗粒平均尺寸分别为60,80,110和115 nm,500 W氙灯照射1.2 V(vs Ag/AgCl)偏压条件下,光电流密度分别为2.4,3.2,3.4和3.5 mA/cm2;柠檬酸的加入有效地改变了薄膜的表面形貌,较高的表面粗糙度和较大的颗粒使得WO3薄膜电极有更好的光电性能。

The influence of citric acid（CA） on microstructure and photoelectrochemical properties of WO3 films was investigated and the mechanism for this behavior was also discussed.WO3 films were prepared using ammonium metatungstate as the precursor,polyethylene glycol as the structure-directing agent and citric acid as the chelating agent by polymer precursor method.The obtained materials were characterized by means of X-ray diffraction,field emission scanning electron microscopy and high-resolution transmission electron microscopy.The photoelectrochemical measurements were performed by using a standard three-electrode system cell.The results indicate that the films prepared with different molar ratios of CA and W（R=0,0.5,1.0 and 2.0） have a particle size of 60,80,110 and 115 nm,showing photocurrent of 2.4,3.2,3.4 and 3.5 mA/cm2 at 1.2 V（vs Ag/AgCl） on the back side,respectively.The enhancement of photocatalytic for citric acid added films may result not only from the improved particles size but also from the reduced internal reflections caused by rougher surfaces.