Electrocatalysis of four-electron oxygen reduction reaction (ORR) provides a promising approach for energy transfer, storage and oxygen monitoring. However, it is always accompanied by the reduction of hydrogen peroxide (H2O2) on most employed catalysts, which brings down the electrocatalytic selectivity. Here, we report a single-atom Co-N4 electrocatalyst for four-electron ORR at an onset potential of 0.68 V (vs. RHE) in neutral media, while with high H2O2 tolerance outperforming commercial Pt electrocatalysts. Electrochemical kinetic analysis confirms that the Co-N4 catalytic sites dominantly promote the direct four-electron pathway of ORR other than the two sequential two-electron reduction pathways with H2O2 as the intermediate. Density function theory calculation reveals that H2O2 reduction is hampered by the weak adsorption of H2O2 on the porphyrin-like Co centers. This endows the electrocatalyst with improved resistance to current interference from H2O2, enabling highly selective O2 sensing as validated by the reliable sensing performance in vivo. Our study demonstrates the intriguing advantage of single-atom catalysts with high capacity of tailoring metal-adsorbate interactions, broadening their applications in environmental and life monitoring.

中文翻译：

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单原子 Co-N4 电催化剂实现四电子氧还原，具有增强的过氧化氢耐受性，用于选择性传感

四电子氧还原反应（ORR）的电催化为能量转移、储存和氧监测提供了一种很有前景的方法。然而，在大多数使用的催化剂上，它总是伴随着过氧化氢（H2O2）的还原，这降低了电催化的选择性。在这里，我们报告了一种用于四电子 ORR 的单原子 Co-N4 电催化剂，在中性介质中的起始电位为 0.68 V（相对于 RHE），同时具有高 H2O2 耐受性，优于商业 Pt 电催化剂。电化学动力学分析证实，Co-N4 催化位点主要促进 ORR 的直接四电子途径，而不是以 H2O2 作为中间体的两个连续的双电子还原途径。密度函数理论计算表明，H2O2 在类卟啉 Co 中心上的弱吸附阻碍了 H2O2 的还原。这使电催化剂对 H2O2 的电流干扰具有更好的抵抗力，从而实现了高度选择性的 O2 传感，正如可靠的体内传感性能所验证的那样。我们的研究证明了单原子催化剂具有定制金属-吸附物相互作用的高能力的有趣优势，扩大了它们在环境和生命监测中的应用。