CO₂ methanation over -Mo_XC catalyst: Effects of phase heterojunction

Modulating the structures of catalysts by heterojunctions has been extensively studied in heterogeneous catalysis. Here, we report a series of MoXC heterostructures, fabricated by phase regulation, for conversion of CO2 to CH4. The alpha beta-MoXC showed a CO2 conversion of 55.2% and CH4 selectivity of 69.8% at reaction temperature of 500 C. The alpha beta-MoXC is not only superior to the pure phase of alpha-MoXC or beta-MoXC, but also better than the commercial MoXC both in CO2 conversion and in CH4 selectivity. High resolution transmission electron microscopy confirms that alpha beta-MoXC is not a simple mixture of alpha and beta crystal phase but possesses a large portion of phase transition state of heterojunction. The larger specific surface area and pore volume, the more alkaline sites along with the Mo2+ components account for the superiority of the alpha beta-MoXC phase heterojunction. The present work provides guidelines for designing heterojunction catalyst in CO2 methanation reaction.