Ionic Liquid-Derived MoC Nanocomposites with Ordered Mesoporosity as Efficient Pt-Free Electrocatalyst for Hydrogen Evolution and Oxygen Reduction

Nanoparticle Size Effects on Phase Stability for Molybdenum and Tungsten Carbides

“…Our comparison focuses on average particle size and neglects particle size distributions (reported in only a subset of studies); we emphasize that our goal is to broadly compare the trends between particle sizes and phases in the literature. The δ-MoC phase dominates the smaller particle size ranges, ,,,,,,− in agreement with our calculations, although there are a few reports of δ-MoC at larger sizes. ,,, Similarly, η-MoC has been synthesized only at small particle sizes <6 nm. ,− The α-Mo 2 C phase has been experimentally synthesized − across a wide range of particle sizes, weighted more heavily toward larger particle sizes, consistent with Figure a. The β-Mo 2 C phase is close in free energy to α-Mo 2 C at all Δμ C and all particle sizes (Figures a,b and S6) and is similarly represented in a wide range of sizes (excluding the 0–3 nm range). ,,,,− ,,,− The one notable exception is the γ-MoC phase, predicted to be more stable at larger particle sizes, which has been synthesized with similar representation at both small (3–6 nm) , and large (>9 nm) − particle sizes and does not appear to follow a trend.…”

Design and modulation principles of molybdenum carbide-based materials for green hydrogen evolution

“…Among various candidates, group VI transition-metal carbides (TMCs) have been widely reported as HER catalysts in view of their similar d-band electronic structures, optimal hydrogenadsorption energy, and catalytic properties to Pt-based metals [16 , 17] . Molybdenum carbides (Mo x C), including Mo 2 C or MoC, as an important member of TMCs, have aroused great interest as efficient HER electrocatalysts since 2012 due to their low cost, earth abundance, good electrical conductivity, similar d-band state to Pt, and regulated morphology/electronic structures [18][19][20][21][22][23][24] . In addition, Mo x C structures exhibit excellent HER activity and stability in a wide pH range.…”

Non-precious Melamine/Chitosan Composites for the Oxygen Reduction Reaction: Effect of the Transition Metal

“…Transition metal carbides are highly attractive since they exhibit electronic and catalytic properties similar to Pt (Guil-López et al, 2010;Roca-Ayats et al, 2014;Zhong et al, 2015). Recently, a number of research groups have demonstrated that molybdenum carbides can be active electrocatalysts for the oxygen reduction reaction (Liao et al, 2014;Fan et al, 2017;Zhang et al, 2017;Li et al, 2019). The physicochemical properties of molybdenum carbides, such as mechanical hardness, thermal stability, singular metal-carbon chemical bonds, and noblemetal-like d-state density around the Fermi level, make them very promising materials for obtaining advanced ORR composites.…”