Toluene combustion over Co3O4-CNTs/PSSF catalysts and investigation of the effects of acid treatment on catalytic activity

Background Co 3 O 4 shows potential as a cost-effective alternative to precious metal catalysts for VOCs catalytic combustion. However, its catalytic activity requires further enhancement. Methods A new type of paper-like carbon nanotube membrane composite (CNTs/PSSF) was used as a support to prepare Co 3 O 4 -CNTs/PSSF catalysts by metal-organic vapor deposition (MOCVD) and impregnation method (IM) respectively for toluene combustion. Besides, the effects of acid treatment to support on the catalytic activity were investigated. Various characterization techniques, including X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), electron paramagnetic resonance (EPR), and oxygen temperature-programmed desorption (O 2 -TPD), were employed to evaluate the effects of different preparation methods and acid treatment on the structure and catalytic performance mechanism of Co 3 O 4 -CNTs/PSSF. Significant findings The preparation method significantly affects the catalyst's properties and catalytic activity. Compared with IM, the MOCVD-prepared catalysts show stronger coordination of carbon nanotubes, resulting in more oxygen vacancies and surface active oxygen. Additionally, oxygenous groups introduced by HNO 3 form Co-O-C linkage between Co and CNTs, promoting oxygen vacancies and enhancing surface active oxygen content, thereby dramatically improving the catalyst's catalytic activity, especially for HIM-10 whose T 90 is reduced by 140 °C. This work provides insights for enhancing the catalytic combustion activity of cobalt oxide.