Oxygen‐Vacancy‐Regulated Piezoelectric Field‐Assisted Photocatalytic Nitrogen Fixation Over La2Ti2O7 Nanosheets

Abstract

Photocatalytic nitrogen fixation is commonly limited by sluggish N2 activation and rapid recombination of photogenerated charge carriers. Here, layered piezoelectric La2Ti2O7 (LTO) nanosheets were used as a model oxide, and Ti3+‐associated oxygen vacancies were introduced by Ar/H2 reduction. Oxygen vacancies created electron‐rich Ti sites, promoted N2 adsorption and charge transfer, and enhanced the local electromechanical response. Under simultaneous light irradiation and ultrasonication, optimized LTO‐600 delivered an NH3 production rate of 148.4 μmol g−1 h−1 in pure water without sacrificial agents. 15N2 isotope labeling confirmed that NH3 originated from N2 reduction. Site‐resolved calculations show that the vacancy‐neighboring Ti site is the principal electron donor, whereas neighboring La weakly polarizes and stabilizes the distal N atom. The combined defect‐mediated N2 activation and piezoelectric‐field‐assisted charge separation account for the enhanced activity.