Shenzhen Key Laboratory of Ecological Remediation and Carbon Sequestration, Guangdong Provincial Engineering Research Center for Urban Water Recycling and Environmental Safety, Institute of Environment and Ecology, Tsinghua Shenzhen International Graduate School, Tsinghua University, Shenzhen 518055, People's Republic of China.
Proc Natl Acad Sci U S A. 2023 Apr 18;120(16):e2219923120. doi: 10.1073/pnas.2219923120. Epub 2023 Apr 11.
The high-valent cobalt-oxo species (Co(IV)=O) is being increasingly investigated for water purification because of its high redox potential, long half-life, and antiinterference properties. However, generation of Co(IV)=O is inefficient and unsustainable. Here, a cobalt-single-atom catalyst with N/O dual coordination was synthesized by O-doping engineering. The O-doped catalyst (Co-OCN) greatly activated peroxymonosulfate (PMS) and achieved a pollutant degradation kinetic constant of 73.12 min g, which was 4.9 times higher than that of Co-CN (catalyst without O-doping) and higher than those of most reported single-atom catalytic PMS systems. Co-OCN/PMS realized Co(IV)=O dominant oxidation of pollutants by increasing the steady-state concentration of Co(IV)=O (1.03 × 10 M) by 5.9 times compared with Co-CN/PMS. A competitive kinetics calculation showed that the oxidation contribution of Co(IV)=O to micropollutant degradation was 97.5% during the Co-OCN/PMS process. Density functional theory calculations showed that O-doping influenced the charge density (increased the Bader charge transfer from 0.68 to 0.85 e), optimized the electron distribution of the Co center (increased the d-band center from -1.14 to -1.06 eV), enhanced the PMS adsorption energy from -2.46 to -3.03 eV, and lowered the energy barrier for generation of the key reaction intermediate (OHO) during Co(IV)=O formation from 1.12 to 0.98 eV. The Co-OCN catalyst was fabricated on carbon felt for a flow-through device, which achieved continuous and efficient removal of micropollutants (degradation efficiency of >85% after 36 h operation). This study provides a new protocol for PMS activation and pollutant elimination through single-atom catalyst heteroatom-doping and high-valent metal-oxo formation during water purification.
高价钴氧物种（Co(IV)=O）因其具有高氧化还原电位、长半衰期和抗干扰特性而被越来越多地用于水净化。然而，Co(IV)=O 的生成效率低且不可持续。在这里，通过 O 掺杂工程合成了具有 N/O 双重配位的钴单原子催化剂。O 掺杂的催化剂（Co-OCN）大大激活了过一硫酸盐（PMS），并实现了污染物降解动力学常数为 73.12 min g，比未掺杂 O 的 Co-CN（无 O 掺杂的催化剂）高 4.9 倍，也高于大多数报道的单原子催化 PMS 体系。Co-OCN/PMS 通过将 Co(IV)=O 的稳态浓度提高 5.9 倍（从 Co-CN/PMS 的 1.03×10 M 增加到 5.93×10 M）来实现污染物的 Co(IV)=O 主导氧化。竞争动力学计算表明，在 Co-OCN/PMS 过程中，Co(IV)=O 对微污染物降解的氧化贡献为 97.5%。密度泛函理论计算表明，O 掺杂影响电荷密度（从 0.68 增加到 0.85 e 的 Bader 电荷转移），优化 Co 中心的电子分布（将 d 带中心从-1.14 增加到-1.06 eV），增强 PMS 吸附能从-2.46 增加到-3.03 eV，并降低 Co(IV)=O 形成过程中关键反应中间体（OHO）生成的能垒从 1.12 降低到 0.98 eV。将 Co-OCN 催化剂负载在碳纤维毡上，用于流动装置，实现了微污染物的连续高效去除（经过 36 小时的运行，降解效率>85%）。本研究为通过单原子催化剂杂原子掺杂和水净化过程中高价金属-氧形成来激活 PMS 和消除污染物提供了新的方案。
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