NiFe2O4 Nanofibers with Surface Oxygen Vacancies for Piezo-Catalytic Hydrogen Peroxide Production

Piezoelectric catalysis is a way of renewable energy conversion, which involves the application of an external mechanical force to a piezoelectric catalyst. In this work, piezoelectric NiFe2O4 nanofibers with surface oxygen vacancies were successfully synthesized by electrospinning and annealing processes. The introduction of surface oxygen vacancies in NiFe2O4 nanofibers can effectively increase the piezo-catalytic degradation rates by 75% for organic dyes and increase the piezoelectric catalytic hydrogen peroxide generation by 39% in pure water. The piezoelectric catalytic mechanism has been discussed. The oxygen defects enhanced the charge transfer rate and the activation of molecular oxygen, providing more reaction sites for the catalytic process. It was confirmed that superoxide radicals (•O2–) played an important role in the whole catalytic process since force-generated electrons (e–) and holes (h+) migrated to the nanofiber surface and redox reactions occurred under the action of the internal electric field. This work provides a piezoelectric catalyst to achieve efficient degradation of dyes and produce hydrogen peroxide.