Developing cobalt-based catalysts with a high abundance of oxygen vacancies (V) and exceptional V utility efficiency for the prompt removal of stubborn contaminants through peroxymonosulfate (PMS) activation poses a significant challenge. Herein, we reported the synthesis of the reduced Mg-doped CoO nanosheets, i.e. Mg-doped CoO-r, via Mg doping and followed by NaBH reduction, aiming to degrade tetracycline (TC). Various characterization results illustrated that NaBH reduction imparted higher V utility efficiency to Mg-doped CoO-r, along with an ample presence of reduced Co species and an increased surface area, thereby substantially elevating PMS activation capability. Notably, Mg-doped CoO-r achieved more than 97.9% degradation of 20 mg/L TC within 10 min, showing an over 8-fold increase in reaction rate relative to the Mg-doped CoO (: 0.3285 min vs 0.0399 min). The high removal efficiency of TC was sustained across a broad pH range of 3–11, even in the presence of common anions and humic acid. Radical quenching trials, EPR outcomes, and electrochemical analysis indicated that neither radicals nor O were the primary active species. Instead, electron transfer pathway played a dominant role in TC degradation. The Mg-doped CoO-r displayed excellent recyclability and versatility. Even after the fifth cycle, it maintained an impressive 83.0% removal of TC. Furthermore, it exhibited rapid degradation capabilities for various pollutants, including levofloxacin, pefloxacin, ciprofloxacin, malachite green, and rhodamine B. The TC degradation pathway was proposed based on LC-MS determination of its degradation intermediates. This study showcases an innovative strategy for the rational design of an efficient cobalt-based activator, leveraging electron transfer pathways through PMS activation to degrade antibiotics effectively.

中文翻译：

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通过还原镁掺杂 Co3O4 活化过一硫酸盐促进四环素降解中氧空位的利用：电子传递途径的动力学和关键作用

开发具有高丰度氧空位 (V) 和出色的 V 利用率的钴基催化剂，通过过一硫酸盐 (PMS) 活化迅速去除顽固污染物是一项重大挑战。在此，我们报道了通过Mg掺杂然后NaBH还原合成了还原的Mg掺杂CoO纳米片，即Mg掺杂CoO-r，旨在降解四环素（TC）。各种表征结果表明，NaBH 还原赋予了 Mg 掺杂 CoO-r 更高的 V 利用率，同时存在大量还原的 Co 物种和增加的表面积，从而显着提高了 PMS 激活能力。值得注意的是，掺镁的 CoO-r 在 10 分钟内实现了 20 mg/L TC 97.9% 以上的降解，相对于掺镁的 CoO，反应速率提高了 8 倍以上（0.3285 分钟 vs 0.0399 分钟）。即使存在常见阴离子和腐殖酸，TC 的高去除效率在 3-11 的广泛 pH 范围内也能保持。自由基猝灭试验、EPR 结果和电化学分析表明自由基和 O 都不是主要活性物质。相反，电子传递途径在 TC 降解中起主导作用。 Mg掺杂CoO-r表现出优异的可回收性和多功能性。即使在第五个周期之后，它仍然保持着令人印象深刻的 83.0% 的 TC 去除率。此外，它对多种污染物表现出快速降解能力，包括左氧氟沙星、培氟沙星、环丙沙星、孔雀石绿和罗丹明B。基于LC-MS对其降解中间体的测定，提出了TC的降解途径。这项研究展示了合理设计高效钴基活化剂的创新策略，通过 PMS 活化利用电子转移途径来有效降解抗生素。