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

Abstract

Molybdenum carbide (MoCx) has been considered as a promising catalyst for CO2 reduction at medium temperature (i.e. >400 °C) because of its excellent ability to dissociate CO2 and H2. However, MoCx catalysts are mainly synthesized at high carburization temperature (i.e., >650 °C), which renders its low active sites exposed and the generation of CH4 by-product, especially at a high H2/CO2 molar ratio. Herein, the core–shell structure nanodiamond @ graphene (ND@G) hybrid with enriched electron density was applied for anchoring MoCx nanoparticles. The as-synthesized MoCx/ND@G catalyst consists of ultra-high exposed MoCx nanoparticles/nanoclusters, exhibiting an extremely high and stable reverse water gas shift (RWGS) catalytic performances (211.5 μmolCO2 gMoCx−1 s−1 at 400 °C and 358.0 μmolCO2 gMoCx−1 s−1 at 600 °C, respectively) with CO selectivity up to 99.5% at H2/CO2 ratio of 4. Remarkably, the MoCx/ND@G catalyst facilitates the CO2 activation at a relatively low temperature compared to MoCx nanoparticles supported by other typical carriers (i.e., activated carbon and γ-Al2O3) and bulk β-Mo2C due to the strong interaction between MoCx 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 CO2 activation.