Liu Yulu, Su Yiguo, Han Hui, Wang Xiaojing
College of Chemistry and Chemical Engineering, Inner Mongolia University, Huhehaote City 010021, PR China.
J Nanosci Nanotechnol. 2013 Feb;13(2):853-7. doi: 10.1166/jnn.2013.6046.
Effects of copper cations doping into wide band gap semiconductor photocatalysts of tantalate on morphology, visible light response, and photocatalytic performance were studied. A series of Cu-doped NaTaO3 catalysts were prepared by hydrothermal method. XRD and XPS results suggested that copper were successfully doped into the NaTaO3 nanocrystal in the Cu2+ state. TEM studies showed the formation of the cube shape nanoparticles of NaTaO3 as well as Cu-doped NaTaO3. UV-Vis diffuse reflectance spectra clearly indicated the red-shift in the series of copper doped NaTaO3 catalysts, resulting in a decrease in the band gap of NaTaO3. The trend of red shift was increased with an increase of copper doping concentration, whereas the photo-degradation methylene blue (MB) is not improved by the doping of copper ions. The simulation of energy band structure by density functional theory unfolded that the substitution of Ta5+ ions by Cu2+ ions results in forming an intermediate band (IB) upper the top of the valence band (VB), which is mainly attributed to the state of Cu 3d. The intermediate band is responsible for the red-shift caused by the doping of Cu ions. Meanwhile Cu species can become the recombination centers of photoinduced electrons and holes. Thus, the quickly recombination of e(-)h(+) pairs is one of the most significant factors which deteriorate the photoactivity of Cu-doped NaTaO3.
研究了铜阳离子掺杂到钽酸盐宽带隙半导体光催化剂中对其形貌、可见光响应和光催化性能的影响。采用水热法制备了一系列铜掺杂的NaTaO₃催化剂。XRD和XPS结果表明，铜以Cu²⁺态成功掺杂到NaTaO₃纳米晶体中。TEM研究表明形成了NaTaO₃以及铜掺杂的NaTaO₃的立方体形纳米颗粒。紫外可见漫反射光谱清楚地表明了一系列铜掺杂的NaTaO₃催化剂中的红移，导致NaTaO₃的带隙减小。红移趋势随着铜掺杂浓度的增加而增大，而铜离子掺杂并未改善亚甲基蓝（MB）的光降解性能。密度泛函理论对能带结构的模拟表明，Cu²⁺离子取代Ta⁵⁺离子导致在价带（VB）顶部上方形成一个中间带（IB），这主要归因于Cu 3d态。中间带是由铜离子掺杂引起红移的原因。同时，铜物种可成为光生电子和空穴的复合中心。因此，e⁻h⁺对的快速复合是恶化铜掺杂NaTaO₃光活性的最重要因素之一。
