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In this work, a novel heterojunction catalyst was constructed by introducing Ti3C2MXene quantum dots (QDs) into SiC. The Ti3C2MXene QDs/SiC composite showed 74.6% efficiency in NO pollutant removal under visible light irradiation, which is 3.1 and 3.7 times higher than those of the bare Ti3C2MXene quantum dots and SiC, respectively. The Ti3C2MXene quantum dots existing in SiC can function as a channel for electron and hole transfer. The enhanced visible light absorption, increased superoxide radical, and strong oxidization ability endow the Ti3C2MXene QDs/SiC composite with a superior photocatalytic performance for NOx removal. The increased superoxide radical formation and enhanced oxidization ability of Ti3C2MXene QDs/SiC were demonstrated by theoretical calculations. The robust stability in both photocatalytic performance and crystal structures was revealed in the Ti3C2MXene QDs/SiC composite using the cycling test, transient photocurrent response, XRD, and TG.

A new microporous MIL-100(Fe)/Ti3C2MXene composite was constructed as a non-noble metal-based Schottky junction photocatalyst with improved nitrogen fixation ability. Ti3C2MXene 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)/Ti3C2MXene 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 Ti3C2MXene 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.