Cadenbach Thomas, Loyola-Plúa María Isabel, Quijano Carrasco Freddy, Benitez Maria J, Debut Alexis, Vizuete Karla
Instituto de Energía y Materiales, Departamento de Ingeniería Ambiental, Colegio Politécnico de Ciencias e Ingenierias, Universidad San Francisco de Quito, Quito 170901, Ecuador.
Departamento de Ingeniería Química, Colegio Politécnico de Ciencias e Ingenierias, Universidad San Francisco de Quito, Quito 170901, Ecuador.
Molecules. 2025 Jul 30;30(15):3190. doi: 10.3390/molecules30153190.
Water pollution caused by increasing industrial and human activity remains a serious environmental challenge, especially due to the persistence of organic contaminants in aquatic systems. Photocatalysis offers a promising and eco-friendly solution, but in the case of bismuth oxide (BiO) there is still a limited understanding of how structural and morphological features influence photocatalytic performance. In this work, a straightforward hydrothermal synthesis method followed by controlled calcination was developed to produce phase-pure α- and β-BiO with tunable morphologies. By varying the hydrothermal temperature and reaction time, distinct structures were successfully obtained, including flower-like, broccoli-like, and fused morphologies. XRD analyses showed that the final crystal phase depends solely on the calcination temperature, with β-BiO forming at 350 °C and α-BiO at 500 °C. SEM and BET analyses confirmed that morphology and surface area are strongly influenced by the hydrothermal conditions, with the flower-like β-BiO exhibiting the highest surface area. UV-Vis spectroscopy revealed that β-BiO also has a lower bandgap than its α counterpart, making it more responsive to visible light. Photocatalytic tests using Rhodamine B showed that the flower-like β-BiO achieved the highest degradation efficiency (81% in 4 h). Kinetic analysis followed pseudo-first-order behavior, and radical scavenging experiments identified hydroxyl radicals, superoxide radicals, and holes as key active species. The catalyst also demonstrated excellent stability and reusability. Additionally, Methyl Orange (MO), a more stable and persistent azo dye, was selected as a second model pollutant. The flower-like β-BiO catalyst achieved 73% degradation of MO at pH = 7 and complete removal under acidic conditions (pH = 2) in less than 3 h. These findings underscore the importance of both phase and morphology in designing high-performance BiO photocatalysts for environmental remediation.
工业活动和人类活动增加所导致的水污染仍然是一项严峻的环境挑战，特别是由于有机污染物在水生系统中具有持久性。光催化提供了一种有前景且环保的解决方案，但对于氧化铋（BiO）而言，人们对其结构和形态特征如何影响光催化性能的了解仍然有限。在这项工作中，开发了一种简单的水热合成方法，随后进行可控煅烧，以制备具有可调形态的纯相α-和β-BiO。通过改变水热温度和反应时间，成功获得了不同的结构，包括花状、西兰花状和融合形态。XRD分析表明，最终的晶相仅取决于煅烧温度，在350°C时形成β-BiO，在500°C时形成α-BiO。SEM和BET分析证实，形态和表面积受水热条件的强烈影响，花状β-BiO表现出最高的表面积。紫外-可见光谱显示，β-BiO的带隙也比其α对应物低，使其对可见光更敏感。使用罗丹明B的光催化测试表明，花状β-BiO实现了最高的降解效率（4小时内为81%）。动力学分析遵循准一级行为，自由基清除实验确定羟基自由基、超氧自由基和空穴为关键活性物种。该催化剂还表现出优异的稳定性和可重复使用性。此外，选择了更稳定且持久的偶氮染料甲基橙（MO）作为第二种模型污染物。花状β-BiO催化剂在pH = 7时实现了73%的MO降解，在酸性条件（pH = 2）下不到3小时即可完全去除。这些发现强调了相和形态在设计用于环境修复的高性能BiO光催化剂中的重要性。
