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

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.