Orbital Coupling of Dual‐Atom Sites Boosts Electrocatalytic NO Oxidation and Dynamic Intracellular Response

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.