Background: Research on catalysts for the efficient conversion of NO 2 to NO is of great significance for the accurate determination of NO 2 concentration and the reduction of environmental pollution. The present work investigated the synergistic interaction between coconut shell activated carbon (AC) and Mo 2 C, along with the catalytic performance of NO 2 to NO. The aim of this study was to prepare a composite catalyst with activated carbon as the support to improve the conversion of NO 2 at low temperatures. The effect of Mo loading w(Mo) on the reaction performance of NO 2 to NO was studied by technical analysis, and the internal mechanism of Mo 2 C/AC for improving the reaction activity of the catalyst was revealed to provide a reference for the development of new efficient NO 2 converting agents.Results: Commercially available Mo 2 C, AC, and Mo 2 C/AC catalysts can convert NO 2 to NO under reaction test conditions. When the gas flow rate is 1.5 L/min and the temperature is 250°C, the NO 2 conversion rates of 5-Mo 2 C/AC, 10-Mo 2 C/AC, 15-Mo 2 C/AC, and 20-Mo 2 C/AC are 96.1%, 97.8%, 97.0%, and 93.2%, respectively. The NO 2 conversion rates of 10-Mo 2 C/AC is about 4 times that of Mo 2 C and 1.1 times that of AC at 250 °C. Conclusion:The Mo 2 C/AC catalyst is rich in micropores and provides a reaction vessel for the conversion of NO 2 to NO. AC with high specific surface area can not only change the dispersion and particle size of Mo 2 C species on the catalyst surface, but also adjust the NOx desorption performance of the catalyst. The synergism between the AC and Mo 2 C of Mo 2 C/AC provides more active sites for NO 2 to NO, improving the reaction performance of the catalyst.