RESUMO
Photothermal catalysis has an advantage in effective and economical elimination technology of volatile organic compounds (VOCs) in the ascendant. Herein, various surface defect engineering routes were adopted to enhance the low-temperature propane oxidation of δ-MnO2. Compared to reducing etchants urea and vitamin C, δ-MnO2 treated with urea - H2O2 exhibited an excellent thermal (T90 = 240 â) and photothermal (T90 = 196 â) activities of propane oxidation. Urea - H2O2 treatment provided high concentration of Mn4+ and surface-active oxygen (Mn4+-Osur) species as surface-active sites, and produced numerous oxygen vacancies to improve charge separation and superoxide species generation capacity. Thus, the photothermal conversion efficiency and low-temperature reducibility were remarkably enhanced. Furthermore, the photothermal synergistic catalytic mechanism was proposed based on in-situ diffuse reflectance infrared Fourier transform spectroscopy and control experiments. The strategy here offered insight into the rational design of efficient transition catalysts, and in-depth understanding of the photothermal catalytic VOCs removal mechanism.
RESUMO
Polyhedral CoOx was synthesized by calcination of Co-based metal-organic framework ZIF-67 and highly dispersed Pt nanoparticles were successfully loaded on CoOx. The catalytic results showed that Ptnano/CoOx had the best activity and stability. As compared with conventional Co3O4, polyhedral CoOx showed more excellent catalytic oxidation performance of toluene, which was related to enhanced oxygen mobility, defective structure and rich active oxygen species provided by Polyhedral CoOx. Moreover, Pt-CoOx metal-support interaction enhanced the dispersion of Pt species and showed more Pt0 ratio. It was reasonable that the gaseous O2 can be activated directly or moved into the catalyst's surface to form oxygen cycle.