Carbon-Aerogel-Confined MoO ₂ as a Robust Nanocatalyst for the Reverse Water–Gas Shift Reaction

Converting CO₂ into syngas via the reverse water-gas shift (RWGS) reaction is promising for carbon cycling, but industrialization is critically dependent on developing efficient non-noble metal catalysts. Mo-based catalysts have been extensively investigated, with molybdenum carbide (Mo₂C) widely regarded as the true active species due to the in situ carburization of MoOx under reaction conditions. Here, we demonstrate that MoO₂ can act as an intrinsically active and stable RWGS catalyst when confined within the matrix of the carbon aerogel. The interface confinement effectively suppresses over-reduction and carburization of MoO₂ after the stability test at 500 °C for 200 h; in contrast, pure MoO₂ nanoparticles start to transform into metallic Mo under the same reaction conditions. This discovery differs from the prevailing argument that MoOx is the precursor to carbides in high-temperature RWGS, highlighting the role of interfacial confinement in stabilizing nanocatalysts.