利用仿生合成的方法在温和条件下制备了微米铜粉/纳米TiO_2复合粒子.选择有机胺对Cu粉进行表面处理,XPS分析表明有机胺通过N原子与表面Cu~(2+)络合形成功能层,在Cu粉表面引入-NH_2和-OH等功能基团,对比实验证实功能基团能够诱导无机氧化物的仿生沉积.XRD结果表明铜粉表面包覆的纳米TiO_2呈现锐钛矿晶型,漫反射光谱(DRS)分析表明,Cu粉经过有机胺处理后在716.5nm处出现了由Cu~(2+)离子与N配位产生的弱吸收.复合粒子的光吸收性能介于TiO_2和Cu粉之间,Cu负载后样品的光吸收阀值从397.5nm红移至448.9nm,红移的原因可归于Cu负载后TiO_2导带下出现新能级,光生电子经过这些中间能级发生跃迁,所需激发能量降低至可见光范围.448.9nm处吸收边的存在表明复合粒子具备可见光催化活性.
Micron size Cu/nano-TiO_2 composite particles were prepared in ambient conditions by bio-inspired method. The surfaces of Cu particles were modified by a kind of amine, and the analysis of XPS in-dicated that the functional layer containing-NH_2 and-OH groups was formed on the surface of Cu particles through the coordination of nitrogen in the amine to Cu~(2+). Comparative experiment confirmed that-NH_2 and -OH groups induced the bio-mineralization of nano-TiO_2 on the Cu surfaces. XRD result showed that TiO_2 of anatase type was deposited on the surfaces of Cu particles. Results of diffuse reflectance spectra (DRS) showed that a weak absorption at 716.5nm occurred after Cu particles were modified by the amine, which in-dicated the coordination of N to Cu~(2+). The photo-absorbance of Cu/nano-TiO_2 composite particles was be-tween the photo-absorbance of TiO_2 and that of Cu. The optical absorption edge of the particles was extended from 397.5nm to about 448.9nm after Cu loading, because Cu loading introduces new mid gap level below the conduction band of TiO_2, and in this way the electron can be excited by visible light through the level.The absorption edge at 448.9nm indicated that Cu/nano-TiO_2 composite particles had the visible light cata-lytic activity.
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