The Catalytic and Adsorptive Synergistic Effect of Oxygen-Vacancy-Rich MnOx/C Catalysts for HCHO Oxidation at Room Temperature

Indoor formaldehyde (HCHO) pollution has attracted extensive attention and shows a carcinogenic effect on humans. However, removal of HCHO still faces the issues of low activity and high-loading noble metals. Herein, we combined catalysis and adsorption into the MnOx/C composite catalysts with abundant oxygen vacancy (VO), which were prepared through a facile in situ synthesis approach between fructose and KMnO4. With the addition of fructose during preparation, the as-achieved MnOx/C-y catalysts not only increased oxygen vacancies but also provided adsorption sites, which showed excellent activity and durability for mineralizing HCHO to CO2 and H2O at room temperature. The HCHO removal efficiency was up to 97.3% for 100 ppm of HCHO and 89.7% for 0.66 ppm of HCHO. Furthermore, no significant downward trend was detected even after four cycles. The rich Mn3+, surface oxygen vacancies, and reactive oxygen species were the main factors for HCHO removal. In situ DRIFTS study revealed that surface −OH accelerated the conversion and oxidation of the formed intermediates.