Synergistic Piezophototronic and Surface Plasmon Effects for Enhanced Solar N2 Reduction: Combined Experimental and Theoretical Insights.

Photoreduction of nitrogen (N2) to ammonia (NH3) driven by plasmon-induced piezo-polarization serves as a highly advanced technique by utilizing various steps of synergistic mechanisms. This work delves into the detailed investigation of the synergistic effects of vacancy-engineered AgCu-modified BiFeO3 (ACBFO) towards plasmon-mediated piezo-polarization-steered solar NH3 production. The optimized catalyst exhibits an NH3 production rate of 278 µmol g-1 h-1 (AQE 0.31%, SCC 0.075%), 2.9-fold higher compared to the pristine counterpart. The characteristic 14N NMR signal verifies NH3 formation, while 15N isotopic labelling confirms its origin from the supplied N2 source. The integration of AgCu nanoparticles over BFO nanosheet induces localized surface plasmon resonance (LSPR), broadening a wide light absorption window. Coincidentally, the Schottky junction of AgCu and BFO allows faster exciton separation, whereas the macroscopic spontaneous piezo-polarization induced by the internal electric field. Mechanical vibration further fastens the charge separation. The presence of Oxygen vacancies (Ovs) enhances charge-carrier lifetime by tuning the electronic structure and reducing the energy barrier for N2 adsorption/activation. A combined experimental and theoretical investigation, including an AI/machine learning (ML) study and finite element method (FEM) simulation, explains the detailed underlying mechanism of carrier dynamics, band structure alignment, and piezo-polarization effects.