Highly Dispersed Molybdenum Oxycarbide Clusters Supported on Multilayer Graphene for the Selective Reduction of Carbon Dioxide.

Molybdenum oxycarbide clusters are novel nanomaterials that exhibit attractive catalytic activity; however, the methods for their production are currently very restrictive. This work represents a new strategy for the creation of near-subnanometer size molybdenum oxycarbide clusters on multilayer graphene. To adsorb Mo-based polyoxometalates of the type [PMo O ] as a precursor for Mo oxycarbide clusters, the novel tripodal-phenyl cation N,N,N-tri(4-phenylbutyl)-N-methylammonium ([TPBMA] ) is synthesized. [TPBMA] exhibits superior adsorption on multilayer graphene compared to commercially available cations such as tetrabutylammonium ([nBu N] ) and tetraphenylphosphonium ([PPh ] ). Using [TPBMA] as an anchor, highly dispersed precursor clusters (diameter: 1.0 ± 0.2 nm) supported on multilayer graphene are obtained, as confirmed by high-resolution scanning transmission electron microscopy. Remarkably, this new material achieves the catalytic reduction of CO to selectively produce CO (≈99.9%) via the reverse water-gas-shift reaction, by applying carbothermal hydrogen reduction to generate Mo oxycarbide clusters in situ.