In situ measurement of nitric oxide (NO) in living tissue and single cells is highly important for achieving a profound comprehension of cellular functionalities and facilitating the precise diagnosis of critical diseases; however, the progress is greatly hindered by the weak affinity of ultratrace concentration NO in cellular environment toward electrocatalysts. Herein, a new strategy is reported for precisely constructing orbital coupled dual-atomic sites to enhance the affinity between the metal atomic sites and NO on a class of N-doped hollow carbon matrix dual-atomic sites Co─Ni (Co₁Ni₁-NC) for greatly boosting electrocatalytic NO performance. The as-synthesized Co₁Ni₁-NC demonstrates a substantially higher current density than Ni₁-NC and Co₁-NC, coupled with exceptional stability with a negligible degradation rate of 0.6 µA·cm⁻²·h⁻¹, which is the best among the state-of-the-art electrocatalysts for NO oxidation. Experimental and theoretical investigations collectively reveal that the pivotal role of d-d orbit coupling between Co and Ni sites enables Ni to acquire additional electrons, leading to the occupation of Ni's 3d_xy/yz within the 2π orbitals of NO, thus weakening the N≡O triple bond and concurrently accelerating NO adsorption kinetics. It is demonstrated that Co₁Ni₁-NC-coated nanoelectrode can achieve the in situ sensing of NO in living organs and single cells.

中文翻译：

---

双原子位点的轨道耦合促进电催化 NO 氧化和动态细胞内反应


活组织和单细胞中一氧化氮 （NO） 的原位测量对于深入了解细胞功能和促进危重疾病的精确诊断非常重要;然而，细胞环境中超痕量浓度 NO 对电催化剂的弱亲和力极大地阻碍了这一进展。在此，报道了一种精确构建轨道耦合双原子位点的新策略，以增强金属原子位点与 NO 在一类 N 掺杂空心碳基双原子位点 Co─Ni （Co₁Ni_1-NC） 上的亲和力，以大大提高电催化 NO 性能。合成的 Co₁Ni_1-NC 表现出比 Ni_1-NC 和 Co_1-NC 高得多的电流密度，并且具有优异的稳定性，降解速率为 0.6 μA^·cm−2·h⁻¹，可以忽略不计，这是最先进的 NO 氧化电催化剂中最好的。实验和理论研究共同表明，Co 和 Ni 位点之间 d-d 轨道耦合的关键作用使 Ni 能够获得额外的电子，导致 Ni 的 3d_xy/yz 占据在 NO 的 2π 轨道内，从而削弱 N≡O 三键，同时加速 NO 吸附动力学。结果表明，Co₁Ni_1-NC 包覆的纳米电极可以实现对活体器官和单个细胞中 NO 的原位感应。