High-density MoCx nanoclusters anchored on nanodiamond-derived nanocarbon as a robust CO2 reduction catalyst for syngas production

Molybdenum carbide (MoC x ) has been considered as a promising catalyst for CO 2 reduction at medium temperature (i.e. >400 °C) because of its excellent ability to dissociate CO 2 and H 2 . However, MoC x catalysts are mainly synthesized at high carburization temperature (i.e., >650 °C), which renders its low active sites exposed and the generation of CH 4 by-product, especially at a high H 2 /CO 2 molar ratio. Herein, the core–shell structure nanodiamond @ graphene (ND@G) hybrid with enriched electron density was applied for anchoring MoC x nanoparticles . The as-synthesized MoC x /ND@G catalyst consists of ultra-high exposed MoC x nanoparticles/nanoclusters, exhibiting an extremely high and stable reverse water gas shift (RWGS) catalytic performances (211.5 μmol CO 2  g MoCx −1  s −1 at 400 °C and 358.0 μmol CO2  g MoCx −1  s −1 at 600 °C, respectively) with CO selectivity up to 99.5% at H 2 /CO 2 ratio of 4. Remarkably, the MoC x /ND@G catalyst facilitates the CO 2 activation at a relatively low temperature compared to MoC x nanoparticles supported by other typical carriers (i.e., activated carbon and γ-Al 2 O 3 ) and bulk β-Mo 2 C due to the strong interaction between MoC x species and curved graphene layers on the surface of ND@G. This study paves a practical strategy for developing a highly efficient molybdenum carbide-based catalyst for CO 2 activation.