Synthesis of Onion-Like δ-MoN Catalyst for Selective Hydrogenation

Synthesis of base metal catalysts with well-defined structure and morphology is highly desired to achieve high catalytic performance for clean energy and green chemistry applications. However, in most catalyst synthesis, it is challenging to control structural manipulation at the nanoscale, especially for transition-metal nitrides, because they are often thermodynamically unfavorable at atmospheric pressure. In this work, we report a high-pressure approach for the formation of hexagonal δ-MoN nanocrystals with a unique onion-like morphology. The onion layers are made of stacked zigzag Mo-N shells associated with the (101) crystallographic plane. Impressively, the as-synthesized δ-MoN possesses intrinsic catalytic activities that are twice higher than the traditional MoS₂ for hydrodesulfurization of dibenzothiophene and more than five times higher in the selectivity to hydrogenation. The nitride is also highly active for selective hydrogenation of diverse nitroarenes to anilines at mild conditions. The enhanced catalytic properties are presumably attributed to the unique zigzag Mo-N bonding structure of the nitride. This work demonstrates that high-pressure synthesis is a viable approach to design and fabricate new and cost-effective transition-metal nitride catalysts for diverse hydrogenation applications.