Hsiao Shan-Yuan, Lin En-Xuan, Keng Pei-Yuin
Department of Materials Science and Engineering, National Tsing Hua University, Hsinchu 300, Taiwan.
Nanomaterials (Basel). 2021 Oct 26;11(11):2853. doi: 10.3390/nano11112853.
The development of a heterogeneous catalyst for use in environmental remediation remains a challenging and attractive research endeavor. Specifically, for Fenton reactions, most research approaches have focused on the preparation of iron-containing heterostructures as photo-Fenton catalysts that utilize visible light for enhancing the degradation efficiency. Herein, the synthesis and novel application of C,N-doped iron borates are demonstrated as single-component heterogeneous photo-Fenton catalysts with high Fenton activity under visible light. Under the optimal conditions, 10 mg of the catalyst is shown to achieve effective degradation of 10 ppm methylene blue (MB) dye, Rhodamine B (RhB) dye, and tetracycline (TC) under simulated solar irradiation with a first-order rate constant of k = 0.218 min, 0.177 min, and 0.116 min, respectively. Using MB as a model system, the C,N-doped iron borate exhibits 10- and 26-fold increases in catalytic activity relative to that of the 50 nm hematite nanoparticles and that of the non-doped iron borate, respectively, in the presence of HO under the simulated solar irradiation. Furthermore, the optimum reaction conditions used only 320 equivalents of HO with respect to the concentration of dye, rather than the several thousand equivalents of HO used in conventional heterogeneous Fenton catalysts. In addition, the as-prepared C,N-doped iron borate achieves 75% MB degradation after 20 min in the dark, thus enabling the continuous degradation of pollutants at night and in areas with poor light exposure. The stability and recyclability of C,N-doped iron borate for the oxidation of MB was demonstrated over three cycles with insignificant loss in photo-Fenton activity. The high Fenton activity of the C,N-doped iron borate is considered to be due to the synergistic action between the negatively-charged borate ligands and the metal center in promoting the Fenton reaction. Moreover, carbon and nitrogen doping are shown to be critical in modifying the electronic structure and increasing the conductivity of the catalyst. In view of its synthetic simplicity, high efficiency, low cost of reagents, and minimal cost of operation (driven by natural sunlight), the as-prepared heterogeneous single-component metal borate catalyst has potential application in the industrial treatment of wastewater.
开发用于环境修复的多相催化剂仍然是一项具有挑战性且颇具吸引力的研究工作。具体而言，对于芬顿反应，大多数研究方法都集中在制备含铁异质结构作为光芬顿催化剂，利用可见光来提高降解效率。在此，展示了C、N掺杂硼酸铁的合成及其作为单组分多相光芬顿催化剂在可见光下具有高芬顿活性的新应用。在最佳条件下，10毫克该催化剂在模拟太阳辐射下能有效降解10 ppm的亚甲基蓝（MB）染料、罗丹明B（RhB）染料和四环素（TC），其一级反应速率常数分别为k = 0.218 min⁻¹、0.177 min⁻¹和0.116 min⁻¹。以MB作为模型体系，在模拟太阳辐射下，在存在HO₂的情况下，C、N掺杂硼酸铁的催化活性相对于50纳米赤铁矿纳米颗粒和未掺杂硼酸铁分别提高了10倍和26倍。此外，最佳反应条件下相对于染料浓度仅使用320当量的HO₂，而不是传统多相芬顿催化剂中使用的数千当量的HO₂。另外，所制备的C、N掺杂硼酸铁在黑暗中20分钟后能实现75%的MB降解，从而能够在夜间和光照较差的区域持续降解污染物。C、N掺杂硼酸铁对MB氧化的稳定性和可回收性在三个循环中得到了证明，光芬顿活性没有明显损失。C、N掺杂硼酸铁的高芬顿活性被认为是由于带负电荷的硼酸配体与金属中心之间在促进芬顿反应方面的协同作用。此外，碳和氮掺杂被证明对于改变电子结构和提高催化剂的导电性至关重要。鉴于其合成简单、效率高、试剂成本低以及运行成本低（由自然阳光驱动），所制备的多相单组分金属硼酸盐催化剂在工业废水处理中具有潜在应用。
