Sustainable Valorization of Methane into Formaldehyde via Atmospheric Gas–Solid Photothermal Catalysis Using a Diatomic Iron Catalyst

Gas–solid photothermal catalytic pathway for methane (CH 4 ) oxidation to formaldehyde (HCHO) at atmospheric pressure addresses product concentration limitations in high-pressure gas–liquid–solid batch systems. However, catalyst deactivation due to slow product desorption and oxygen replenishment remains a challenge. Here, inspired by methane monooxygenase, Fe 2 diatomic anchored ZnO catalyst (Fe 2 –ZnO) were synthesized to addresses such challenge. The Fe 2 diatomic pairs enhance charge separation, promoting C–H bond of CH 4 cleavage, while their weak interaction with oxygen species facilitates *HCHO desorption, enabling gaseous HCHO production with the assistance of heat. Additionally, the strong interaction between Fe 2 pairs and ZnO enhances charge accumulation around the Fe 2 diatomic pairs, facilitating O 2 adsorption, activation, and oxygen vacancy replenishment. Thus, the Fe 2 –ZnO catalyst achieves an HCHO production rate of 31.8 mmol g cat –1 h –1 (71.7% selectivity) and superior stability (<10% activity loss over 50 h). And a concentrated HCHO solution (579.7 μmol mL –1, 1.74 wt %) is obtained via water absorption at 0 °C for 12 h. These findings provide references for the application of diatomic catalysts in CH 4 conversion.