Promoted photocatalytic N2 fixation to ammonia over floatable TiO2/Bi/Carbon cloth through relay pathway

Abstract

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.