Giant molybdenum‐based polyoxometalate clusters create ultrafine molybdenum carbide nanoparticles with smaller and narrower size distribution and superior catalytic activity for the hydrogen evolution reaction. Abstract Due to its electronic structure, similar to platinum, molybdenum carbides (Mo2C) hold great promise as a cost‐effective catalyst platform. However, the realization of high‐performance Mo2C catalysts is still limited because controlling their particle size and catalytic activity is challenging with current synthesis methods. Here, the synthesis of ultrafine β‐Mo2C nanoparticles with narrow size distribution (2.5 ± 0.7 nm) and high mass loading (up to 27.5 wt%) on graphene substrate using a giant Mo‐based polyoxomolybdate cluster, Mo132 ((NH4)42[Mo132O372(CH3COO)30(H2O)72]·10CH3COONH4·300H2O) is demonstrated. Moreover, a nitrogen‐containing polymeric binder (polyethyleneimine) is used to create MoN bonds between Mo2C nanoparticles and nitrogen‐doped graphene layers, which significantly enhance the catalytic activity of Mo2C for the hydrogen evolution reaction, as is revealed by X‐ray photoelectron spectroscopy and density functional theory calculations. The optimal Mo2C catalyst shows a large exchange current density of 1.19 mA cm−2, a high turnover frequency of 0.70 s−1 as well as excellent durability. The demonstrated new strategy opens up the possibility of developing practical platinum substitutes based on Mo2C for various catalytic applications.
Published in: "Small".