Interfacial Schottky junctions modulated by photo-piezoelectric band bending to govern charge carrier migration for selective H₂O₂ generation

A major challenge faced by most systems is the dissociation of O−O bonding on H₂O₂ by subsequent electron (e^-) reduction. This study investigates interfacial charge transfer by manipulating e^- flows through a deflexed band potential on polarized piezoelectric BiFO₃ (BFO). The H₂O₂ accumulation via coupling with the photocatalyst BiOCl/BiVO₄ (BCV) was highly effective since the Schottky barrier height (SBH) formed within the heterojunction composite shifted according to the surface polarity of BFO. Additionally, the constant alternating surface charge on BFO, reduced the SBH, forcing the photoexcited e^- to flow from BCV→BFO for effective H₂O₂ production, while restricting decomposition of H₂O₂ during downshifted band potential (positive surface) as high SBH discontinuing the electrons flow from BCV→BFO. The high interfacial charge transfer resistance (R_ct) was also critical for H₂O₂ accumulation, since it is unfavorable for H₂O₂ dissociation (H₂O₂/·OH, +0.39 V) despite the presence of a high band potential (+0.16 eV) on the opposite surface's upshifted band. The formation rate (k_f: 1.13 µmol L⁻¹ min⁻¹) of H₂O₂ was calculated much higher than decomposition rate (k_d: 0.01 min⁻¹). Additionally, the RRDE results indicated favorable 2e^- transfer with > 90 % selectivity for H₂O₂. Results from ESR DMPO-·OH abduction and atrazine degradation show an insignificant concentration of ·OH has been produced. This work provides an effective strategy to regulate semiconductors' surface junction by piezoelectric polarization for selective H₂O₂ generation.