Photocatalytic N 2 fixation to NH 3 via defect creation on TiO 2 to activate ultra-stable N [Private characterTRIPLE BOND, LENGTH AS M-DASH ] N has drawn enormous scientific attention, but poor selectivity and low yield rate are the major bottlenecks. Additionally, whether N 2 preferentially adsorbs on phase-selective defect sites on TiO 2 in correlation with appropriate band alignment has yet to be explored. Herein, theoretical predictions reveal that the defect sites on disordered anatase (A d) preferentially exhibit higher N 2 adsorption ability with a reduced energy barrier for a potential-determining-step (*N 2 to NNH*) than the disordered rutile (R d) phase of TiO 2. Motivated by theoretical simulations, we synthesize a phase-selective disordered-anatase/ordered-rutile TiO 2 photocatalyst (Na-A d/R o) by sodium-amine treatment of P25-TiO 2 under ambient conditions, which exhibits an efficient NH 3 formation rate of 432 μmol g −1 h −1, which is superior to that of any other defect-rich disordered TiO 2 under solar illumination with a high apparent quantum efficiency of 13.6% at 340 nm. The multi-synergistic effects including selective N 2 chemisorption on the defect sites of Na-A d with enhanced visible-light absorption, suitable band alignment, and rapid interfacial charge separation with R o enable substantially enhanced N 2 fixation.
This work highlights the importance of a rational design for more energetically suitable nitrogen reduction reaction routes and mechanisms by regulating the electronic band structures with phase-selective defect sites.