过氧化氢是一种重要的化工原料,在造纸、化学合成等方面有着广泛应用。与传统的蒽醌工艺相比,电催化生产过氧化氢避免了有机溶剂的大量使用和高浓度过氧化氢溶液储存和运输危险。电催化2e−ORR是制备过氧化氢的重要途径,其中具有高活性和选择性的电催化剂起着重要作用。锰是生物体的必需元素,含有锰的酶参与了许多代谢过程。锰超氧化物歧化酶(Mn-SOD)是人体中一种重要的金属酶,其作用是捕获超氧自由基并将其歧化成O2和H2O2。Mn-SOD中的Mn中心由N和O原子共同配位。利用希夫碱配体模拟Mn-SOD的配位结构,构建了一些O2相关反应的均相催化剂。如含有MnN2O2Cl中心的Mn(tbudhbpy)Cl催化2e-ORR的H2O2法拉第效率(FE)为81%。然而, 2e-ORR的Mn基非均相催化剂很少被报道。1. 开发了一种受自然启发的单原子电催化剂,包含N、O配位的Mn位点,并利用碳点作为调制平台(Mn CD/C)。合成的Mn CD/C具有优异的2e- ORR活性,起始电位为0.786 V,最大H2O2选择性为95.8%。 2. Mn CD/C在液流池中以200 mA/cm2的电流密度连续产生0.1 M H2O2溶液50 h,活性和H2O2法拉第效率几乎没有损失,展示了其实际应用潜力。3. 理论计算表明,N、O共配位结构与碳点上丰富的含氧官能团相结合,优化了中间体*OOH在Mn位点的结合强度,达到了催化活性火山的顶峰。
Figure 1. Schematic synthesis process of Mn CD.(图片来源:Angew. Chem. Int. Ed.)Figure 2. a) FT-IR spectra of Mn CD, CD, and Na2[Mn(EDTA)]. b) XPS high-resolution O 1s spectrum of Mn CD. c) Normalized Mn K-edge XANES spectra, d) EXAFS spectra, and e) WT-EXAFS of Mn CD/C and reference samples.(图片来源:Angew. Chem. Int. Ed.)Figure 3. a) LSV curves, b) H2O2 selectivity and electron transfer number, c) comparison of onset potential and ring current at 0.7 V, and d) Tafel plot of Mn CD/C, CD/C, and MnPc/C. e) LSV curves of Mn CD/C before and after KSCN poisoning. f) Chronoamperometry test of Mn CD/C at 0.50 V.(图片来源:Angew. Chem. Int. Ed.)Figure 4. a) Scheme of the flow cell. b) LSV curve, c) current density and H2O2 FE at different potentials, and d) chronopotentiometry test of Mn CD/C in the flow cell.(图片来源:Angew. Chem. Int. Ed.)Figure 5. a) Optimized configurations and b) differential charge density of MnNG, MnN4, MnN2O2, MnN2O2(O), and MnN2O2(O-COOH).c) Bader charge density and ΔG*OOH of different structures. d) Calculated catalytic activity volcano for 2e− ORR, correlating ΔG*OOH and UL of different structures.(图片来源:Angew. Chem. Int. Ed.)
Yuan Zeng, Zewen Zhuang*, Chen Chen*, Qing Peng * et al. Nature-inspired N, O Co-Coordinated Manganese Single-Atom Catalyst for Efficient Hydrogen Peroxide Electrosynthesis. Angew. Chem. Int. Ed. 2024.
DOI:10.1002/anie.202416715
https://doi.org/10.1002/anie.202416715
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