MIL-100(Fe)/Ti₃C₂ MXene as a Schottky Catalyst with Enhanced Photocatalytic Oxidation for Nitrogen Fixation Activities

Abstract

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.