Enhancement of the catalytic performance of Co-ZIF/WO 3 heterostructures for selective catalytic reduction of NO x .

Nitrogen oxides (NOx) are one of the growing air pollutants in industrial countries, and their emissions are regulated by stringent legislation. Therefore, the design of the catalyst comprised of metal oxides and ZIFs a potential solution for improving selective catalytic reduction (SCR) of NOx. Here, an efficient strategy was described to fabricate Co-ZIF/WO 3 heterostructures for SCR of NOx. First, WO 3 nanostructures were fabricated by the solvothermal method, and subsequently epitaxial growth of ZIF-67 on the metal oxide surface to create a new type of semiconductor Co-ZIF/WO 3 heterostructures. The obtained heterostructures were systemically characterized by wide-angle XRD, FESEM, UV DRS, FT-IR, AFM, and TEM spectroscopies. The Co-ZIF/WO 3 heterostructures shift the temperature corresponding to the maximum conversion around 50 °C towards lower temperatures. The maximum conversion is substantially enhanced from 55% at 400 °C to 78% at 350 °C. The enhanced activity is attributed to better interaction and synergic effect of WO 3 incorporated into ZIF-67 and also the electron transfer facility between the WO 3 and Co species in Co-ZIF/WO 3 heterostructures. Moreover, Co-ZIF/WO 3 results in a distinct effect on the production of carbon monoxide (CO) in the product gas stream. The current study highlights some of the challenges in the development of semiconductor-based heterostructures for a decrease in air pollution.