Programmable Electrochemiluminescence From a Self‐Emissive TiO ₂ Fabry–Pérot Cavities With Integrated Photonic–Plasmonic–Chemical Coupling

ABSTRACT Constructing intrinsically emissive and structurally programmable interfaces is key to unlocking next‐generation electrochemiluminescent (ECL) materials. Here we develop a cavity‐engineered TiO 2 nanotube architecture that integrates photonic confinement, plasmonic amplification, and redox‐programmable chemical gating within a single functional platform. The corrugated TiO 2 nanotubes spontaneously form Fabry–Pérot cavities that provide wavelength‐selective photon recycling, yielding strong intrinsic ECL from the TiO 2 /S 2 O 8 2− pair. Decorating the cavity entrance with Au nanoparticles creates a dual photonic–plasmonic enhancement pathway, boosting the ECL output up to an order of magnitude through synergistic electromagnetic coupling and nanoscale mirror effects. To impart programmable signal control, MnO 2 nanosheets are incorporated as a chemical gating module that modulates cavity resonance and plasmonic feedback via redox‐dependent etching. This hierarchical design enables continuous, stepwise, and threshold‐type ECL programmability, offering deterministic control over emission behavior. Leveraging these features, the platform achieves ultrasensitive alkaline phosphatase detection (LOD: 1.5 × 10 −3 U L −1 ) and discriminates bacterial species through their endogenous enzymatic signatures. The integrated photonic–plasmonic–chemical strategy establishes a generalizable framework for constructing programmable ECL materials, offering new opportunities for tunable light–matter interaction and adaptive optoelectronic biointerfaces.