Upconversion hollow nanospheres CeF_(3) co-doped with Yb^(3+) and Tm^(3+) for photocatalytic nitrogen fixation

Solar driven nitrogen(N_(2))fixation to synthesize ammonia is a potential alternative for the traditional Haber-Bosch approach to meeting industrial demand,but is largely hampered by the difficulties in the harvesting of solar energy and activating inert N_(2).In this work,hollow CeF_(3) nanospheres co-doped with activator Tm^(3+)and sensitizer Yb^(3+)(Yb^(3+):Tm^(3+):CeF_(3))were prepared by microwave hydrothermal method.The product was employed as a catalyst for photo-driven N_(2) fixation by adjusting the molar ratio of Ce^(3+):Yb^(3+):Tm^(3+).Results show that the porous hollow structure enhances the light-harvesting by physical scattering and reflection.In addition,heteroatom doping generates abundant fluorine vacancies(F_(V))which provide abundant active sites for adsorption and activation of N_(2).The sample with molar ratio of CeF_(3):Yb^(3+):Tm^(3+)at 178:20:2 demonstrates the highest utilization of solar energy attributed to the strongest upconversion capability of near-infrared(NIR)light to visible and ultraviolet(UV)light,and the NH_(4)+concentration achieves the highest value of 15.06μmol/(gcat∙h)under simulated sunlight while nearly 6.22μmol/(gcat∙h)under NIR light.Current study offers a promising and sustainable strategy for the fixation of atmospheric N_(2) using full-spectrum solar energy.

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 180μmol·L?1·ho1 when the molar ratio of Pr3+to LaOF was optimized to be 2%.