Two-step pyrolytic engineering of carbon-doped Mn3O4 with rich defects for efficient photothermal acetone oxidation

Efficient photothermal catalysts are crucial for effective light energy utilization and low-energy-driven catalytic oxidation reaction of oxygenated volatile organic compounds (OVOCs). Herein, defect-rich carbon-doped Mn₃O₄ samples were successfully synthesized through a two-step calcination process of Mn-MIL-100 under various atmospheres. Among them, Mn₃O₄/C-N6A2 exhibited the optimal performance, achieving a 91 % CO₂ yield and a 92 % acetone conversion under the entire spectrum simulated sunlight while maintaining stability for at least 100 h. The high activity can be due to the beneficial synergies of carbon's photothermal-assisted properties, numerous oxygen vacancies, and Mn³⁺ active sites. Additionally, carbon doping could also improve the catalytic performance of Mn₃O₄ by enhancing light-absorbing capacity, charge transmission efficiency, and reactive oxygen species (ROS) formation. Furthermore, light-driven thermocatalysis, photoactivation, and photocatalysis coexist, ensuring an efficient and sustained photothermal catalytic acetone oxidation. Besides, oxygen vacancies accelerated the adsorption and activation of gaseous oxygen and promoted intermediates such as acetaldehyde and carboxylate, deep oxidation into CO₂ and H₂O. Therefore, this study offers an innovative approach to designing and fabricating efficient carbon-doped metal oxide photothermal catalysts.