Yang Ruofan, Liang Baiping, Zheng Shizheng, Hu Changyuan, Xu Yajuan, Ma Yanting, Bai Yangyang, Dai Kejie, Tang Yan, Zhang Cuiqing, Chang Miao
Jiangxi Key Laboratory of Surface Engineering (School of Materials and Mechanical & Electrical Engineering), Jiangxi Science and Technology Normal University, Nanchang 330013, P. R. China.
Key Laboratory of Bio-based Material Science and Technology (Ministry of Education), Northeast Forestry University, 26 Hexing Road, Harbin 150040, P. R. China.
Inorg Chem. 2022 Sep 5;61(35):14102-14114. doi: 10.1021/acs.inorgchem.2c02163. Epub 2022 Aug 25.
The oxygen-deficient bismuth oxide, BiO, synthesized by a typical hydrothermal method using commercial NaBiO·2HO as a raw material only has a relatively low concentration of surface oxygen vacancies (OVs). How to improve the visible light photocatalytic performance of BiO via tuning its surface OV concentration is still a huge challenge. In this study, improving the surface OVs of BiO was successfully realized through the pretreatment of commercial NaBiO·2HO, including thermal treatment in air and hydrothermal treatment in 10 M NaOH solution, forming NaBiO·HO intermediate products first, and then hydrothermal preparation of BiO target products using NaBiO·HO instead of commercial NaBiO·2HO as the precursor. The enhanced surface OV content not only narrows the band gap of BiO and thus extends its optical response range but also captures more photoexcited electrons and thus increases the charge carriers' separation efficiency and prolongs the charge carriers' lifetime of BiO. Among the above-mentioned two pretreatment methods, the effects of the hydrothermal pretreatment are superior to those of the thermal treatment, involving the increase of surface OVs, the optical harvesting capacity, and the charge carriers' separation efficiency. Accordingly, BiO prepared by the hydrothermal pretreatment route exhibits the optimal visible light catalytic performance toward the removal of methyl orange (MO) and phenol due to its most abundant surface OV concentration, which is 2.59 times and 4.26 times higher than that of BiO synthesized directly by the commercial NaBiO·2HO route, respectively. Holes (h) and superoxide radicals (O) are identified as the main active species, while singlet oxygen (O) and hydroxyl radicals (OH) are verified as the second and third important active species for organic pollutant removal, respectively. This work has developed a novel strategy to promote the catalytic performance of single BiO induced by the enhanced surface OV concentration through the pretreatment of the precursor, commercial NaBiO·2HO.
采用典型水热法，以市售NaBiO₃·2H₂O为原料合成的缺氧氧化铋BiO，其表面氧空位（OVs）浓度相对较低。如何通过调节其表面OV浓度来提高BiO的可见光光催化性能仍是一个巨大挑战。在本研究中，通过对市售NaBiO₃·2H₂O进行预处理成功实现了BiO表面OVs的增加，预处理包括在空气中进行热处理以及在10 M NaOH溶液中进行水热处理，首先形成NaBiO₂·H₂O中间产物，然后以NaBiO₂·H₂O代替市售NaBiO₃·2H₂O作为前驱体水热制备BiO目标产物。增强的表面OV含量不仅使BiO的带隙变窄从而扩展其光响应范围，还捕获了更多的光激发电子，进而提高了BiO的电荷载流子分离效率并延长了电荷载流子寿命。在上述两种预处理方法中，水热预处理的效果优于热处理，包括表面OVs的增加、光捕获能力以及电荷载流子分离效率的提高。因此，通过水热预处理路线制备的BiO对甲基橙（MO）和苯酚的去除表现出最佳的可见光催化性能，这是由于其表面OV浓度最为丰富，分别比直接由市售NaBiO₃·2H₂O路线合成的BiO高2.59倍和4.26倍。空穴（h⁺）和超氧自由基（O₂⁻）被确定为主要活性物种，而单线态氧（¹O₂）和羟基自由基（·OH）分别被证实为去除有机污染物的第二和第三重要活性物种。这项工作通过对前驱体市售NaBiO₃·2H₂O进行预处理，开发了一种通过增强表面OV浓度来提升单一BiO催化性能的新策略。
