J. Mater. Sci. Technol. ›› 2025, Vol. 214: 180-193.DOI: 10.1016/j.jmst.2024.06.038

• Research Article • Previous Articles     Next Articles

MXene-based 2D/2D Ti3C2/TiO2 heterojunction with spatially separated redox sites for efficient photocatalytic N2 reduction towards NH3

Chi Caoa, Jinshuo Lia, Linfeng Zhanga, Yang Hua, Lin Zhangb,*, Wensheng Yanga,b,*   

  1. aState Key Laboratory of Inorganic Synthesis and Preparative Chemistry, College of Chemistry, Jilin University, Changchun 130012, China;
    bEngineering Research Center for Nanomaterials, Henan University, Kaifeng 475004, China
  • Received:2024-03-23 Revised:2024-06-12 Accepted:2024-06-25 Published:2025-04-10 Online:2025-04-05
  • Contact: *E-mail addresses: lin.zhang@henu.edu.cn (L. Zhang), wsyang@jlu.edu.cn (W. Yang)

Abstract: Herein, a new type of two-dimensional (2D)/2D Ti3C2/TiO2 heterojunction was developed for efficient photocatalytic nitrogen reduction reaction (NRR), in which TiO2 nanosheets (TiO2 Ns) were designed as the main catalyst, while Ti3C2 MXene served as the co-catalyst. Experimental and theoretical results revealed that Ti3C2 MXene introduced electron-rich unsaturated Ti sites, serving as highly active sites for both the adsorption and activation of N2 on the Ti3C2/TiO2 heterojunction. Furthermore, the 2D/2D Ti3C2/TiO2 heterostructure greatly promoted the directional separation and transfer of charge carriers, facilitated by the internal electric field. This structural feature enabled the spatial separation of the N2 reduction and H2O oxidation half-reactions on the distinct surfaces of Ti3C2 (001) and TiO2 (001), consequently reducing the reaction energy barrier for each respective process. The synergistic effects arising from the interface and surface interactions within the heterojunction conspicuously improved the photocatalytic NRR activity. As a result, the optimized Ti3C2/TiO2 heterojunction exhibited a high NH3 production rate of 24.4 µmol g-1 h-1 in the absence of sacrificial agents, representing a remarkable 12.8-fold increase compared to individual TiO2 Ns. This work provides new insights into rational design of high-performance heterogeneous photocatalysts and offers a deeper understanding of the mechanism underlying surface active sites in the photocatalytic NRR process.

Key words: 2D/2D heterojunction, Ti3C2 MXene, Photocatalytic N2 reduction reaction, N2 adsorption and activation, Spatially separated redox sites