Efficiently catalytic purification of indoor formaldehyde upon Co-N sites derived from ZIF-67 carbonization
Résumé
The catalytic elimination of formaldehyde (HCHO) by low-cost transition metal catalysts at ambient temperature has been a challenge. In this study, ZIF-67 as precursor was introduced to construct a series of Co-based catalysts supported by N-doped carbon (Co/NC-X) via the pyrolysis at different temperatures in N2 atmosphere. The catalyst obtained by pyrolysis of ZIF-67 at 700 °C (Co/NC-700) exhibited a HCHO conversion reaching 96 % at 25 °C. The characterizations and theoretical calculations showed that the abundant defect sites on the surface of Co/NC-700 generated by the rearrangement of N atoms into the hexagonal ring of graphitic carbon could anchor the exposed active cobalt component, forming Co-N1 centers and promoting the cobalt dispersion. Co-N1 centers are beneficial for the dissociation of adsorbed oxygen molecules into reactive oxygen species (ROS), which can accelerate the oxidation of intermediates along with a better activity.