Flower-like BiOI/Bi₅O₇I type-II heterojunctions with oxygen vacancies (OVs) have been in-situ constructed by calcining flower-like BiOI obtained by a hydrothermal tactic with the assistance of water hyacinth powder (WHP). The photocatalysts were characterized by specific surface area, X-ray diffraction pattern (XRD), scanning electron microscope (SEM), high-resolution transmission electron microscopy (HRTEM), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS) and electron spin resonance spectroscopy (ESR). The efficient photogenerated carriers separation of the photocatalysts was demonstrated by surface photovoltage spectrum (SPS) and photocurrent experiments. The trapping experiments determine that h⁺ and •O₂⁻ are the main active free radicals in the visible light driven (VLD) photocatalytic system. Low-temperature ESR proves the existence of OVs, which greatly promotes the photocatalytic activity. When the mass ratio of WHP/Bi(NO₃)₃•5H₂O is 8%, the prepared BiOI/Bi₅O₇I photocatalyst represents the best photocatalytic performance under visible light irradiation. The removal rate constant of Rhodamine B (RhB) and phenol over the 8% samples is 0.022 min⁻¹ and 0.24 h⁻¹, which is 27 and 3-fold of that over the 0% sample, respectively. The effective transfer and efficient utilization of photogenerated e⁻/h⁺ and the presence of OVs jointly improve the activity of the BiOI/Bi₅O₇I composite photocatalyst. This work develops an effective strategy for synthesis of visible light driven photocatalytic materials by taking advantage of biomass.

通过在水葫芦粉 (WHP) 的帮助下煅烧通过热液策略获得的花状 BiOI，原位构建了具有氧空位 (OV) 的花状 BiOI/Bi ₅ O ₇ I II 型异质结。通过比表面积、X射线衍射图（XRD）、扫描电子显微镜（SEM）、高分辨率透射电子显微镜（HRTEM）、拉曼光谱、X射线光电子能谱（XPS）和电子自旋共振对光催化剂进行表征光谱（ESR）。通过表面光电压谱（SPS）和光电流实验证明了光催化剂的有效光生载流子分离。捕获实验确定 h ⁺和 •O ₂^-是可见光驱动（VLD）光催化系统中的主要活性自由基。低温ESR证明了OVs的存在，极大地促进了光催化活性。当WHP/Bi(NO ₃ ) ₃ •5H ₂ O的质量比为8%时，制备的BiOI/Bi ₅ O ₇ I光催化剂在可见光照射下表现出最好的光催化性能。罗丹明B (RhB) 和苯酚对8% 样品的去除速率常数为0.022 min ^-1和0.24 h ^-1，分别是0% 样品的27 倍和3 倍。光生e ⁻ /h ⁺的有效转移和高效利用OVs的存在共同提高了BiOI/Bi ₅ O ₇ I复合光催化剂的活性。这项工作开发了一种利用生物质合成可见光驱动光催化材料的有效策略。