Novel composite photocatalysts MIL-100 (Fe) modified with carbon quantum dots (CQDs) were prepared via a simple one-step hydrothermal method. The photocatalytic performances were indagated through the gas phase NO removal experiment under visible-light illumination. Compared with the pure MIL-100 (Fe), the CQDs@MIL-100 (Fe) material showed excellent photocatalytic performance, with a maximum of 70% NO removal efficiency. The composite photocatalysts were systematically characterized with SEM, XRD, BET, DRS, PL, and FTIR. The results showed that CQDs were successfully coupled with the MIL-100 (Fe) via the C-O bond. The introduction of CQDs enhanced the utilization of sunlight and photoexcited-charge utilization efficiency, which in turn promoted the conversion of NO to NO3-. (C) 2021 Elsevier B.V. All rights reserved.

A new microporous MIL-100(Fe)/Ti3C2 MXene composite was constructed as a non-noble metal-based Schottky junction photocatalyst with improved nitrogen fixation ability. Ti3C2 MXene nanosheets exhibited excellent metal conductivity and were employed as two-dimensional support to optimize the composite's energy band structure. MIL-100(Fe) with a large specific surface area was used as an adsorbent and a photocatalytic oxidation center. The MIL-100(Fe)/Ti3C2 MXene composite not only exhibited higher thermal stability but also showed significantly increased nitrogen fixation activity under visible light. The NO conversion rate of the composite catalyst was about four and three times higher than that of the pure Ti3C2 MXene and the pure MIL-100(Fe) samples, respectively. Although adsorption plays an important role in the nitrogen fixation process, the synergistic effects of the Schottky junctions are the main cause of the enhanced photocatalytic activity. The built-in electric field can be generated to form charge-transfer channels, which help to achieve a desirable photocatalytic activity.