Switching Cathodic/Anodic Electrochemiluminescence of Ru(bpy)32+ Precisely via Homogeneous Nickel Nanoparticles Crystal Facets Sites Modulated ORR/OER

ABSTRACT Reactive oxygen species (ROS) have gained increasing attention in electrochemiluminescence (ECL) as endogenous co‐reactants, yet their application in the most widely used tris(bipyridine)‐ruthenium(II) system remains limited due to the scarcity of suitable co‐reactant accelerators (CRAs) with selective oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) catalytic activity. Here, this work reports a series of facet‐tunable homogeneous NiNPs catalysts, which can stimulate ECL at distinguishable cathodic/anodic potentials in tris(bipyridine)‐ruthenium(II) system. Experimental studies and theoretical calculation results reveal that the Ni(1 1 0) surface, with its lower charge density, impedes the fourth step of 4e − ORR, thus favoring 2e − pathway and consequently promoting substantial ROS generation and ECL at the cathode. Conversely, the Ni(1 1 1) and (2 0 0) surface prompt robust and stable anodic ECL via hydroxyl radical by controlling the OER. These excellent CRAs link cathodic/anodic ECL with ORR/OER, offering a novel strategy for precisely designing predictable non‐precious metal CRAs. Furthermore, sensitive immunosensors were developed using these CRAs, demonstrating successful application in potential‐resolved ECL analysis for practical purposes.