为了研究混合相异质结对光催化的改性机理, 以五水硝酸铋、六水硝酸钕、偏钒酸钠为原料, 浓硝酸、氢氧化钠为调和剂, 水热合成不同浓度钕掺杂钒酸铋样品。X射线衍射和拉曼峰位分析发现, 钒酸铋呈现钕浓度依赖的单斜到四方相转变。采用扫描电子显微镜表征发现, 这种相变给样品形貌带来巨大变化。小于1at%钕掺杂单斜钒酸铋由不规则颗粒堆积而成, 大于7at%钕掺杂四方相由类似球状或凹槽表面果仁状构成, 而中间混合相由微米长方体棒状组成。规则形貌导致所有掺杂样品光催化降解罗丹明B效率高于无掺杂样品。高分辨透射电子显微镜和莫特-肖特基测试发现, 混合相中形成交错能带异质结, 进一步促进光生电-子空穴对分离并抑制其复合, 使得4at%钕掺杂样品具有99.4%降解效率。

To investigate the modification mechanism of mixed heterogeneous on photocatalysis, a series of Nd³⁺-doped BiVO₄ photo-catalysts with different Nd³⁺ contents were synthesized through a facile hydrothermal reaction. The samples exhibit Nd³⁺ content-dependent phase transition from monoclinic to tetragonal phase, as demonstrated by XRD and Raman analyses. SEM images show that the phase transition is accompanied by obvious morphology variation. Less than 1at% Nd³⁺-doped monocline BiVO₄ is composed of irregular particles, while more than 7at% Nd³⁺ doping results in tetragonal phase BiVO₄ of sphere-like or kernel with groove surface. When Nd³⁺content is in the range of 1at%-7at%, the micron cuboid bars appear in the samples. More importantly, monoclinic and tetragonal phase is concomitant in the product and a heterogeneous junction with staggered band structure is formed. The Rhodamine B degradation efficiencies of all Nd³⁺-doped samples are higher than those of undoped samples due to the regular morphology after doping. The formed heterogeneous junction inhibits photo-generated electrons and holes recombination of Nd³⁺-doped BiVO₄, inducing 99.4% catalytic efficiency in 4at% Nd³⁺-doped sample. The novel morphology and the intrinsic mechanism of photocatalysis enhancement upon Nd³⁺-doped BiVO₄ are obtained from the synthesis strategy and the energy band structure.