Insights into highly efficient piezocatalytic molecule oxygen activation over Bi2Fe4O9: Active sites and mechanism

Piezocatalytic molecular oxygen activation has been regarded as a promising and low energy-cost strategy for environment remediation, yet the piezocatalytic activity is still far from satisfactory and little is known on its activation mechanism, which greatly hinders its further development. Herein, the piezocatalyst Bi 2 Fe 4 O 9 nanosheets (BFO NSs) are synthesized via a facile hydrothermal method, which exhibit excellent piezocatalytic performance for sulfamethoxazole degradation. O 2 ∙ - ${\mathrm{O}}_2^{\bullet -}$ generated via the molecular oxygen reduction reaction by piezo-electrons and the piezo-holes were confirmed as major active species for organic pollutants degradation. Further theoretical calculations and XPS analyses confirm the Fe 2+ sites as active centers activate molecular oxygen into O 2 ∙ - ${\mathrm{O}}_2^{\bullet -}$ via donating the electrons to molecular oxygen and the piezo-electrons reduce Fe 3+ to Fe 2+ . This work provides atomic-scale insights into the active sites of piezocatalytic molecular oxygen activation, which can inspire the development of more efficient piezocatalysts for environment application.