Promoted photocatalytic N 2 fixation to ammonia over floatable TiO 2 /Bi/Carbon cloth through relay pathway.

The floatable photocatalyst at N2 -water interface allows the adequate supply of N2 reactant and the utilization of photothermal energy for photocatalytic N2 fixation, however, the presence of non-volatile NO3 - product poses a challenge to the stability as it easily covers the catalytic active sites. Herein, a floatable TiO2 /Bi/CC (Carbon cloth) photocatalyst was designed, in which the non-volatile NO3 - can be transformed to the volatile NH3 via the newly synergistic relay photocatalysis pathway (N2  → NO3 -  → NH3 ) between TiO2 (N2  → NO3 - ) and Bi (NO3 -  → NH3 ). Attractively, the spontaneous NO3 -  → NO2 - step occurs on Bi component to promote the relay pathway performing. Therefore, TiO2 /Bi/CC system displays better long-term stability than TiO2 /CC, and moreover, it achieves a higher NH3 yield of 8.28 mmol L-1  h-1  g-1 (i.e. 4.14 mmol h-1  m-2 ) than that 1.46 mmol L-1  h-1  g-1 for TiO2 /Bi powder. Importantly, the N2 fixation products by TiO2 /Bi/CC effectively promote lettuce growth and enhance lettuce nutrient contents, which further validates the feasibility of this system in large-scale application of crop cultivation.