Magnetic field-enhanced photocatalytic nitrogen fixation over defect-rich ferroelectric Bi2WO6

Photocatalytic N 2 fixation is a promising and sustainable manufacturing process of ammonia (NH 3 ); however, the NH 3 production rate by this method is very low, thus severely restricting further application of this sustainable technology. Therefore, developing an efficient photocatalyst for N 2 fixation under mild conditions is urgently required. Herein, ferroelectric Bi 2 WO 6 materials with different surface oxygen defects were prepared, and the concentration of corresponding defects was controlled by adjusting the thermal reduction time. The abundant oxygen defects in Bi 2 WO 6 can provide more reactive sites to promote the effective adsorption of N 2 , and the photogenerated charge carrier can be efficiently separated benefiting from the internal electric field. These would weaken the N 2 triple bond and reduce the activation energy barrier for the conversion of N 2 to NH 3 under mild conditions. In the absence of sacrificial agents and cocatalysts, the optimized Bi 2 WO 6 with oxygen defects shows an indigenous NH 3 yield of 132.175 μmol·g -1 ·L -1 ·h -1 , which is more than two times higher than that of the original Bi 2 WO 6 . Surprisingly, the Bi 2 WO 6 with oxygen defects produced more than eight times NH 3 (471.13 μmol·g -1 ·L -1 ·h -1 ) than that of the original Bi 2 WO 6 when assisted by an external magnetic field, thus providing a new perspective for further enhancing the N 2 fixation performance.