Operando Analysis of Hot Electron Dynamics and Schottky Barrier Modulation in Hierarchical Au/WO3 Inverse Opal Photonic Crystal Micro-Chip for Enhanced Gas Sensing

Au nanoparticle-modified WO₃ inverse opal photonic crystals (Au/WO₃ IOPCs) exhibit exceptional NO₂ sensing via synergistic hierarchical porosity, Au catalytic activity, and plasmonic hot electrons. A pioneering multimodal environmental operando microspectroscopy platform integrates photoconductive AFM, Kelvin probe microscopy, and in situ DRIFTS with computational modeling. This approach achieves atomic-scale spatiotemporal resolution of interfacial dynamics, directly revealing: (i) plasmonically generated hot electrons fluxing across the Au/WO₃ interface to activate NO₂ adsorption and modulate electron depletion layers under illumination and (ii) dynamic Schottky barrier reconfiguration at electrode junctions that quantitatively correlates environmental stimuli (gas concentration, photon flux, temperature) with resistance evolution. By bridging nanoscale charge transfer to device-level responses, the study establishes a transformative methodology for plasmon-enhanced photonic sensors while providing fundamental insights into interfacial processes, enabling knowledge-driven development of high-precision detectors with ultimate sensitivity and selectivity.