Sustainable CO₂ conversion is crucial in curbing excess emissions. Molybdenum carbide catalysts have demonstrated excellent performances for catalytic CO₂ conversion, but harsh carburization syntheses and poor stabilities make studies challenging. Here an unsaturated Mo oxide (Mo₁₇O₄₇) shows a high activity for the reverse water–gas shift reaction, without carburization pretreatments, and remains stable for 2,000 h at 600 °C. Flame spray pyrolysis synthesis and Ir promoter facilitate the formation of Mo₁₇O₄₇ and its in situ carburization during reaction. The reaction-induced cubic α-MoC with unsaturated Mo oxycarbide (MoO_xC_y) on the surface serves as the active sites that are crucial for catalysis. Mechanistic studies indicate that the C atom in CO₂ inserts itself in the vacancy between two Mo atoms, and releases CO by taking another C atom from the oxycarbide to regenerate the vacancy, following a carbon cycle pathway. The design of Mo catalysts with unsaturated oxycarbide active sites affords new territory for high-temperature applications and provides alternative pathways for CO₂ conversion.

可持续的CO ₂转化对于抑制过量排放至关重要。碳化钼催化剂在催化CO ₂转化方面表现出优异的性能，但苛刻的渗碳合成和较差的稳定性使研究具有挑战性。此处，不饱和钼氧化物 (Mo ₁₇ O ₄₇ ) 在逆水煤气变换反应中表现出高活性，无需渗碳预处理，并且在 600 °C 下保持稳定 2,000 小时。火焰喷射热解合成和Ir促进剂促进了Mo ₁₇ O ₄₇的形成及其在反应过程中的原位渗碳。反应诱导的立方 α-MoC 表面具有不饱和 Mo 碳氧化物 (MoO _x C _y )，作为催化至关重要的活性位点。机理研究表明，CO ₂中的C原子将自身插入到两个Mo原子之间的空位中，并通过碳循环路径中的另一个C原子再生空位来释放CO。具有不饱和碳氧化物活性位点的Mo催化剂的设计为高温应用提供了新领域，并为CO ₂转化提供了替代途径。