CuO和CuS量子点修饰单晶TiO_2纳米棒阵列及光电转化性能表征

CuO and CuS quantum dot sensitized single-crystal TiO_2 nanorod arrays and their photoelectrical performance

通过浸渍沉积法,对TiO2纳米棒阵列进行了CuO和CuS量子点修饰。通过场发射扫描电镜可以清楚观察到量子点均匀分散于TiO2纳米棒表面,粒子尺寸随反应物中Cu2+的浓度增加而增大,且CuS比CuO尺寸大,颗粒间团聚严重。修饰前后TiO2的晶相组成没有发生明显变化,均为正方金红石相,含铜量子点的结晶相也未出现。在模拟太阳光辐射下,少量的CuO和CuS量子点沉积都能显著提高复合体系的光电响应,最高短路光电流密度分别约为空白TiO2的5倍和3.5倍,说明表面量子点敏化提高了光致电荷分离与转移效率。过量的CuO和CuS沉积会导致粒子尺寸的增大和团聚,不利于和TiO2之间的电荷转移,光电流随之降低。另外,CuO敏化TiO2的光电转化性能和稳定性都要优于CuS,推测这是由于CuS粒子大,易团聚,并且在光照下容易得电子形成更加稳定的Cu2S所致。

The decoration of TiO2 nanorod arrays with CuO and CuS quantum dots （QDs）was carried out through the dipping and deposition process.CuO and CuS QDs uniformly dispersed on the surface of TiO2 nanorods,and the particle size increased with the increase in concentration of Cu2＋ in reactants.In addition,CuS particles were much larger and more aggregated than CuO nanoparticles.The crystallinity of TiO2 was tetragonal rutile phase,and had no obvious changes before and after the QD sensiti-zation,and no typical peaks of the QDs containing Cu（II）could be observed.Under the irradiation of solar simulator,the photo-current response of the composite system can be improved by the deposition of CuO or CuS QDs and the highest photocurrent den-sity was around 5 or 3 .5 times that of the TiO2 ,respectively,indicating that the photoinduced charge separation and transfer were certainly promoted by the introduction of these cupric QDs.The deposition of too high concentraition QDs could result in o-ver growth and aggregation of the grains,which may hinder the charge transfer between the QDs and TiO2 ,thus reducing the photocurrent.Furthermore,the enhanced photoelectrical activity and stability of TiO2 sensitized by CuO was always higher than that of CuS,which can be due to large and aggregated CuS QDs and the production of more stable Cu2 S resulted from capturing the photogenerated electrons under the illumination.