Microwave hydrothermal synthesis of lanthanum oxyfluoride nanorods for photocatalytic nitrogen fixation: Effect of Pr doping

Photocatalytic fixation of nitrogen has been recognized as a green and promising strategy for ammonia synthesis under ambient conditions. However, the efficient reduction of nitrogen remains a challenge due to high activation energy of nitrogen and low utilization of solar energy. Herein, lanthanum oxyfluoride with different doping content of Pr3+ (LaOF:xPr3+) upconversion nanorods were synthesized by microwave hydrothermal method. Results indicated that the doping of Pr3+ generated considerable defects on the surface of LaOF which acted as the adsorption and activation center for nitrogen. Meanwhile, the Pr3+ ion narrowed the band gap and broadened the light response range of LaOF because LaOF:Pr3+ can upconvert visible light into ultraviolet light, which excite LaOF nanorods and improve the utilization of solar light. The doping amount of Pr3+ had critical effect on the photocatalytic nitrogen fixation performance which reached as high as 180 μmol·L−1·ho1 when the molar ratio of Pr3+ to LaOF was optimized to be 2%.