摘要
基于TiO2/Ti电极在含Cu2+溶液中的循环伏安图,调节电沉积的沉积电压,我们在TiO2平整表面制备出Cu2O和/或Cu颗粒.通过扫描电镜(SEM)、X射线衍射(XRD)和X射线光电子能谱(XPS)表征,发现Cu2O和Cu有不同的生长机制:Cu2O颗粒在TiO2表面分散结晶,而Cu颗粒是在已生长的颗粒上成核,从而形成堆积颗粒结构.这是由于在Cu2O/TiO2界面和Cu/TiO2界面形成不同的能带结构,使得电子的转移方式不同.与纯TiO2光阳极比较,可以观察到Cu2O/TiO2和Cu/TiO2异质结构的光电流均有显著增强.特别地,存在一个电压区间使得Cu2O和Cu同时生长在TiO2表面,此时对应的光电流比较稳定并且能达到最大.紫外-可见(UV-Vis)漫反射光谱、电化学阻抗谱(EIS)和光电流-电压特性曲线均显示,Cu2O和Cu明显有助于光的可见光吸收,同时Cu/TiO2在光电转换过程中显示更宽波段的可见光利用率.此外,开路电压的增加、有效的电荷分离和电极/电解质界面上载流子的快速迁移也增强了材料的光电化学性质.
Based on the cyclic voltammogram （CV） of TiO2/Ti electrodes in Cu^2＋ ion solution, we fabricated Cu2O and Cu particles onto TiO2 flat surfaces separately or simultaneously by adjusting the applied potentials during electrodeposition. Scanning electron microscopy （SEM）, X-ray diffraction （XRD） and X-ray photoelectron spectroscopy （XPS） showed that Cu2O and Cu have different growth modes： Cu2O particles crystallize on the TiO2 surface separately while Cu particles nucleate on previously grown particles, forming a stacked particle structure. This growth behavior can be explained by the different electron transfer behavior on the Cu2O/TiO2 and Cu/TiO2 interfaces and this is determined by their bandgap alignments. Compared with a pure TiO2 photoanode, a significant enhancement of the photocurrent was observed for both the Cu2O/TiO2 and Cu/TiO2 heterostructures. A potential region exists where Cu2O and Cu grow on the TiO2 surface simultaneously and the corresponding photocurrent is relatively stable and reaches a maximum. UV-Vis diffuse reflectance spectroscopy, electrochemical impedance spectroscopy （EIS）, and photocurrent vs potential characteristics revealed that the visible light absorption by Cu20 and Cu contributes significantly to the photocurrent. Cu/TiO2 resulted in greater broadband visible light utilization during the photoelectric conversion. Additionally, the increased zero-current potential and the effective charge separation as well as the rapid carrier transfer on the electrode/electrolyte interface are also related to the enhanced photoelectrochemical properties.
出处
《物理化学学报》
SCIE
CAS
CSCD
北大核心
2014年第10期1867-1875,共9页
Acta Physico-Chimica Sinica
基金
supported by the National Natural Science Foundation of China(91233109,51272166,11004146)
Natural Science Foundation of Jiangsu Province,China(BK2012622)
Priority Academic Program Development of Jiangsu Higher Education Institutions(PAPD),China~~
关键词
氧化亚铜
铜
电化学沉积
光电化学性质
二氧化钛薄膜
Cuprous oxide
Copper
Electrochemical deposition
Photoelectrochemical property
Titatium oxide film
