Promoted photocatalytic N₂ fixation to ammonia over floatable TiO₂/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.