Oxygen Vacancy Engineering of Bi₄Ti₃O₁₂ Piezocatalyst Driving In Situ H₂O₂ Evolution for Self-Cycled Fenton-Like Degradation of Pollutants

In this work, we synthesized a Bi₄Ti₃O₁₂ piezocatalyst with surface oxygen vacancy (BTO-Ov) to facilitate in situ hydrogen peroxide (H₂O₂) production and to establish a piezocatalytic self-cycled Fenton-like system for degradation of pollutants. Notably, the H₂O₂ evolution rate from the BTO-Ov catalyst reaches 558.8 μmol g^-1 h^-1 when utilizing pure water, significantly exceeding the rate obtained from pure BTO (274.6 μmol g^-1 h^-1). Furthermore, this rate can be enhanced to 1091.6 μmol g^-1 h^-1 with the addition of ethanol as a sacrificial agent and endows robust stability. In the piezocatalytic self-cycled Fenton-like system (BTO-Ov/Fe⁰), degradation efficiency of the methyl orange (MO) dye pollutant can achieve 91.9% within 20 min, coupled with a high kinetic coefficient of 0.117 min^-1, indicating excellent catalytic activity. Relevant characterization results reveal that the introduction of oxygen vacancy improves piezoelectricity, reduces the band gap of BTO, enhances charge carrier transfer and separation, and facilitates a dual-channel reaction mechanism, thereby achieving superior piezocatalytic performance. This work not only facilitates the in situ synthesis of valuable chemicals but also offers a cost-effective and sustainable approach for wastewater purification.