An Artificial Neuromorphic Opto‐Gas Synergistic Device Based on a Two‐Dimensional Perovskite Oxide for Acid Rain Warning

The development of multifunctional artificial synapses capable of integrating molecular sensing and physical stimuli detection remains a challenge due to limited material systems that exhibit both multi-modal responsiveness and tunable synaptic characteristics. Herein, we report two-dimensional perovskite oxide La₂Ti₂O₇ (LTO) nanosheets that are semiconducting and ion conductive, rendering them sensitive to humidity, NO₂ gas, and light. A two-terminal device based on the LTO nanosheets exhibited tunable synaptic behaviors and input-dependent switching between excitatory and inhibitory postsynaptic currents. Importantly, a long-term inhibitory memory was achieved, resulting from the light-triggered reaction between environmental H₂O and NO₂ molecules, which deprived H₂O from the LTO surface to bring LTO to a high resistance state. As a proof-of-concept, our two-terminal device was employed for evaluation and early warning of potential acid rain scenarios, demonstrating its advantage of reducing system complexity compared to a conventional system that requires multiple sensors and logic processors. Our work provides a new strategy of using multi-functional sensing materials for artificial synapses in responding to environmental chemical processes.