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

Abstract

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.

Magnetic origin of phase stability in cubic γ-MoN

“…Using a special high-pressure (P) reaction route, we have recently synthesized a series of interesting TM nitrides in W-N, 27 Mo-N, [28][29][30] Cr-N, 31,32 and V-N systems, 33 including synthesis of c-MoN x single crystals. 30 In this work, we further have investigated this nitride with both experiments and first-principles calculations with a focus on its phase stability from the perspective of magnetism.…”

Low temperature synthesis of plasmonic molybdenum nitride nanosheets for surface enhanced Raman scattering

“…It is well known that the bulk δ−MoN is probably one of the most stable materials, with extremely high hardness, melting point, and corrosion resistance 25 , 27 . In order to test whether these ultrathin δ−MoN nanosheets still have these excellent properties, we examined their thermal and chemical stability.…”

“…Among these transition metal nitrides, δ−MoN has attracted extensive attention due to their catalytic properties similar to platinum-group metals, energy storage, and superconductivity properties 21 – 24 . However, δ−MoN is inert in thermodynamics under an ambient pressure, so it is a great challenge to prepare δ−MoN with controllable structures 25 . So far, the synthesis of δ−MoN generally requires high temperature (above 1000 °C) and high pressure (up to severe GPa) 26 .…”

Effect of Fe, Co and Ni promoters on MoS2 based catalysts for chemoselective hydrogenation of nitroarenes

“…The coordinative unsaturated sites (CUS) at the edge of MoS 2 slabs have been deemed as the active centers in the hydrodesulfurization (HDS) and hydrodeoxygenation (HDO). 48 They are also postulated as the reaction sites in the selective hydrogenation of nitroarenes owing to the similar hydrogenation process. Due to NO molecule can adsorb on CUS, the NO temperatureprogrammed desorption (NO-TPD) experiment was used to estimate the amount of CUS on the MoS 2 /g-Al 2 O 3 and promoted MoS 2 catalysts.…”