Bifunctional RbBiNb₂O₇/poly(tetrafluoroethylene) for high-efficiency piezocatalytic hydrogen and hydrogen peroxide production from pure water

Overall water splitting initiated by the green energy is a challenging yet promising route to address the worldwide environmental and energy issues. Herein, we report the implementation and unraveling of the piezoelectric effect of RbBiNb₂O₇/poly(tetrafluoroethylene) (RBNO/PTFE) on promoting the thermodynamically favorable 2e^- reaction to significantly enhance their overall water splitting (i.e., simultaneously producing H₂O₂ and H₂) via piezocatalysis. HRTEM, XPS and FTIR results confirm the successful preparation of RBNO/PTFE. The piezo-responses of RBNO/PTFE are uncovered by PFM. Remarkably, exceptional H₂ and H₂O₂ production rates (i.e., 260.79 and 219.23 μmol g^-1h^-1, respectively) are achieved over RBNO/PTFE in pure water without cocatalysts upon the ultrasonic excitation, far exceeding those of pure RBNO and PTFE. Specifically, the piezoelectric polarization of PTFE causes the band tilt of RBNO, leading to the energy match between the required redox potential and the band structure of RBNO towards dynamically favorable H₂ and ·OH mediated H₂O₂ generation. In addition, the hydrophobic modification of PTFE over RBNO makes water oxidation reaction occur toward the H₂O₂ production. Given the diversity of materials possessing the mechanical-force-to-chemical-energy conversion, this work may provide a robust way to underpin future advances in the catalytic renewable-energy production.