A Bimetallic Covalent Organic Framework Photonic Synaptic Electrocatalysts

Photonic synaptic electrocatalysts encode catalytic activity as a writable, retainable state under optical stimulation, enabling history-dependent performance modulation with potential relevance to scenarios such as intermittent solar illumination and artificial metabolic learning systems. However, most photo-assisted electrocatalysts are stateless, showing only transient activity enhancement under illumination that vanishes once the light is removed. Here, we establish a photonic synaptic electrocatalyst based on a bimetallic covalent organic framework (Co-Ni─COF), in which optical stimulation writes synaptic information into the catalytic state, and oxygen evolution serves as a stringent functional readout. During electrochemical reactions, Co─Ni─COF shows strong photonic synaptic behavior, featuring excitatory postsynaptic current responses, tunable synaptic plasticity, transitions from short-term to long-term plasticity, learning-forgetting-relearning behavior, and long-term memory retention. Mechanistic investigations reveal that this light-written and retained state originates from strengthened electronic coupling between Co and Ni centers, promoted charge delocalization and intermetallic charge transfer, and the accumulation of metastable Co(III) active species together with key oxygenated intermediates (*OOH, *OO). Notably, a substantial fraction of enhanced catalytic activity is preserved for hours in the dark, maintaining ∼127% higher than the initial state after 3 h, highlighting its potential for efficient energy conversion under intermittent solar illumination.