Switching Cathodic/Anodic Electrochemiluminescence of Ru(bpy)₃ ²⁺ Precisely via Homogeneous Nickel Nanoparticles...

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.