Ambient Sunlight Driven Photothermal Green Syngas Production at 100 m³ Scale by the Dynamic Structural Reconstruction of Iron Oxides with 38.7% Efficiency

Abstract Ambient sunlight‐driven photothermal green syngas production via reverse water‐gas shift (RWGS) reaction is important for carbon neutrality, which lacks efficient and inexpensive catalysts at low temperatures. This studydemonstrates that the scalable Fe 3 O 4 supported with K atoms modified Ag nanoparticles (AgK/Fe 3 O 4 ) exhibits a RWGS CO production rate of 1089 mmol g −1 h −1 at 300 °C and 100% CO selectivity through dynamic structural reconstruction, surpassing all reported platinum‐based catalysts. In situ characterization and theoretical simulation indicate that the AgK nanoparticles activate H 2 to reduce Fe 3 O 4 as metallic Fe. Subsequently, the metallic Fe spontaneously reacts with CO 2 to form CO and Fe 3 O 4 , thereby facilitating low‐temperature RWGS. Owing to its superior low‐temperature performance, AgK/Fe 3 O 4 equipped with a homemade photothermal device achieves one sun‐driven photothermal RWGS with a CO production rate of 1925 mmol g −1 h −1 and a 38.7% solar to enthalpy energy conversion efficiency. Furthermore, the enlarged outdoor demonstration yields 100.6 m 3 day −1 of green syngas with an H 2 /CO ratio of 3. This work paves the way for designing efficient platinum‐free CO 2 hydrogenation catalysts and introduces a new approach for sunlight‐driven scalable green syngas production.