Interfacial Dual Sites on Mo-MXene-Based Catalysts for Highly Efficient Ammonia Synthesis under Mild Conditions

The development of nonprecious metal (NPM) catalysts for ammonia (NH3) synthesis under mild conditions remains highly challenging, since the competitive adsorption of reactants (N2 and H2) and NH3 at active sites is a trade-off and detrimental to NH3 synthesis. Herein, we report a series of ZrH2-modified Mo-MXene (MX) catalysts for efficient NH3 synthesis, leveraging the synergistic effect of interfacial dual sites. The developed 40MX-ZrH2 catalyst shows a high NH3 synthesis rate of 15.7 mmol g–1 h–1 at 400 °C and 1 MPa, outperforming most reported NPM-based catalysts. Our studies demonstrate that the ball-milling process decreases the grain size of both Mo2CTx and ZrH2, thereby generating abundant interfacial dual sites. Although Mo-MXene is highly active for N2 activation through a dissociative route, its strong affinity for N species impedes H2 activation and NH3 desorption. The incorporation of ZrH2 not only is responsible for H2 activation and storage but also donates electrons to Mo2CTx to accelerate NH3 desorption. Thus, the interfacial dual sites in MX-ZrH2 synergistically promote the activation of N2 and H2 along with the desorption of NH3, enabling efficient NH3 synthesis under mild conditions.