The water‐gas shift (WGS) reaction (CO+H₂O→CO₂+H₂) is critical in producing high‐purity hydrogen for ammonia and methanol synthesis as well as in fuel cell applications.

By the concept of single‐atom catalysts (SAC), scientists now can understand the chemical bond and electronic structure between metal and support in an atomic scale.

A research group led by Prof. WANG Xiaodong and Prof. ZHANG Tao from the Dalian Institute of Chemical Physics (DICP) of the Chinese Academy of Sciences (CAS), in collaboration with Prof. LI Jun from Tsinghua University, proposed a redox mechanism with synergetic dual metal active sites for the WGS reaction on a Ir₁/FeO_x SAC. The results were published in Angew. Chem. Int. Ed.

The scientists reported a combined theoretical and experimental study on SAC of Ir₁/FeO_x for WGS reaction. They found that water easily dissociated to OH* on the Ir₁ single atom and H* on the nearby O atom bonded with a Fe site. The adsorbed CO on Ir₁ reacts with the adjacent O atom to produce CO₂. Then, the formation of H₂ became feasible due to migration of H from adsorbed OH* toward Ir₁ and its subsequent reaction with another H*.

They proposed a new pathway of a redox mechanism via synergetic dual metal active sites between Ir₁ and Fe species (DMAS) during the WGS reaction, which demonstrated the sequential production of CO₂ and H₂.

The elucidation of the catalytic mechanism involving this kind of dual metal active sites might provide insights for understanding the catalytic mechanism of metal catalysts with reducible supports, thus helping rational design of new and active dual-site single-atom and single-cluster catalysts.

This work was supported by the National Natural Science Foundation of China, the Youth Innovation Promotion Association of CAS. (Text by LIN Jian)

Synergetic dual metal active sites of Ir₁/FeO_x SAC for WGS reaction (Image by LIN Jian)