Synergistic Interplay of a Dual Active Site on a Mo₂N@ZrO₂ Heterostructure for a Low-Temperature Reverse Water–Gas Shift Reaction

The construction of the active site is pivotal in the design of highly efficient catalysts for heterogeneous catalysis. Notably, the synergy between the two active sites can substantially enhance the catalytic efficiency. Nonetheless, fabricating high-density dual active sites on the catalyst surface remains a significant challenge. In this study, the host-guest strategy was employed to construct a dual active site Mo₂N@ZrO₂ heterostructure catalyst, featuring a significant number of nitrogen sites and oxygen vacancies. The Mo₂N@ZrO₂ catalyst exhibited near-equilibrium conversion and 100% CO selectivity in a reverse water-gas shift reaction at 350 °C. Density functional theory (DFT) calculations and <i>in situ</i> diffuse reflection infrared Fourier transform (DRIFT) spectroscopy characterization indicate that oxygen vacancies on the Mo₂N@ZrO₂ catalyst dissociate CO₂ into CO, while Mo₂N promotes H₂ to form NH_<i>x</i> species by heterolytic dissociation. The formation of NH_<i>x</i> facilitates the desorption of CO and inhibits the further hydrogenation of CO*. This synergistic effect of the dual active site significantly enhances catalytic performance. This strategy of constructing a dual active site offers valuable insights for developing efficient catalysts.