A simple, solvent-free and scalable route for the synthesis of nanostructured Bi₅O₇NO₃ and Bi₂O₃ polymorphs photocatalysts and their heterostructures is here presented. Morphology, porosity and crystal phases were tuned by controlling the thermal decomposition of Bi(NO₃)₃:5H₂O, by using different calcination temperatures and cooling processes. Bi₅O₇NO₃ layered nanosheets, highly porous β-Bi₂O₃/Bi₅O₇NO₃ heterostructured nanoflakes and micrometric sheets of α-Bi₂O₃ were obtained at temperatures of 400 °C, 425–450 °C and 525 °C with a slow cooling rate, respectively. Moreover, in contrast to previous reports on Bi₅O₇NO₃, the role on the visible-light driven photocatalytic activity of Bi₅O₇NO₃ due to the formation of a stable heterojunction with β-Bi₂O₃, which here was identified to be also formed by a rapid cooling after calcination at 400 °C, was deeply investigated and demonstrated. All the samples were fully characterized by X-ray Diffraction, Field-emission scanning electron microscopy, UV–vis spectroscopy, N₂ adsorption and X-ray Photoelectron Spectrometry analyses. The role of oxygen vacancies, which indicate structural defects and/or sub-stoichiometric forms of Bi₅O₇NO₃ or Bi₂O₃ in the photocatalysts surface, was also analyzed and correlated to their photo-response. Simulated sunlight-driven degradation of organic dyes with different functionalities, i.e. a cationic dye (Rhodamine B) and an anionic one (Indigo Carmine), was investigated and proved to be optimized due to an efficient synergy between suitable amounts of Bi₅O₇NO₃ and β-Bi₂O₃ in the heterostructured samples. An improved charge carriers separation at the heterojunction interphase and an enhanced formation of reactive oxygen species in these materials were additionally confirmed by both photocatalytic water oxidation experiments with O₂ evolution and mineralization of a refractory anionic dye, i.e. Remazol Brilliant Blue R. The latter was reached with an optimum photocatalyst/dye weight ratio of 33, which is about 2–3 times lower than previous literature results.

本文介绍了一种简单，无溶剂且可扩展的路线，用于合成纳米结构的Bi ₅ O ₇ NO ₃和Bi ₂ O ₃多晶型光催化剂及其异质结构。通过使用不同的煅烧温度和冷却工艺，通过控制Bi（NO ₃）₃：5H ₂ O的热分解来调节形态，孔隙率和晶相。毕₅ ø ₇ NO ₃的层状纳米片，高度多孔的β-Bi系₂ ö ₃ /铋₅ ö ₇ NO ₃异质结构的纳米片和α-Bi系的微米薄片₂ ö ₃在400℃，425-450℃，和525℃的温度下以慢冷却速度分别获得。此外，与以前的报告上的Bi ₅ ö ₇ NO ₃，对Bi的可见光驱动光催化活性的作用₅ ø ₇ NO ₃由于具有稳定的异质结的形成β-Bi系₂ ö ₃对此进行了深入的研究和证明，其中在400°C下煅烧后迅速冷却也形成了这种粉末。通过X射线衍射，场发射扫描电子显微镜，紫外可见光谱，N ₂吸附和X射线光电子能谱分析对所有样品进行了充分表征。还分析了氧空位的作用，这些空位表明了光催化剂表面中Bi ₅ O ₇ NO ₃或Bi ₂ O _3的结构缺陷和/或亚化学计量形式，并与它们的光响应相关。模拟阳光驱动的具有不同功能的有机染料的降解，即阳离子染料（若丹明B）和阴离子一个（靛蓝胭脂红），进行了调查和证实被优化，由于合适的量的Bi之间的有效协同作用₅ ö ₇ NO ₃和β-Bi系₂ ö ₃的异质样品英寸 通过具有O ₂析出的光催化水氧化实验和难熔阴离子染料（即无机盐）的矿化作用，还进一步证实了这些材料在异质结界面处的电荷载流子分离得到改善，并且活性氧物种的形成也得到了增强。 Remazol Brilliant BlueR。达到后者的最佳光催化剂/染料重量比为33，比以前的文献结果低约2-3倍。