Ti(3)C(2)-induced interface reconstruction of CeO(2) and in-situ derived TiO(2) boosting electron transfer and oxygen vacancies generation for efficient low-temperature soot oxidation over CeO(2)/Ti(3)C(2).

内容摘要

CeO2-based catalysts have been employed in soot oxidation in diesel engine exhaust owing to their excellent oxygen storage and release capacity derived from Ce3+/Ce4+ redox cycle. However, CeO2 still suffers from high reaction temperature limitation for soot oxidation, which seriously degrades its catalytic activity and reusability. Since soot oxidation degree strongly depends on active oxygen species and contact area, this study introduced Ti3C2 into CeO2 to construct CeO2-Ti3C2 with multiple heterojunctions, thereby enhancing CeO2 electron migration to form appropriate quantity of oxygen vacancies on the surface. The results indicated that CeO2/Ti3C2 construction induced TiO2 derivation and formed Schottky heterojunctions including TiO2/Ti3C2 and CeO2/Ti3C2, which increased interfacial electron transfer paths for effective active oxygen species generation. Among synthesized catalysts, CeO2/Ti3C2-12 exhibited a light-off temperature (T10, 242 °C) and half-conversion temperature (T50, 410 °C). Compared with the T10 and T50 values of CeO2 in this study and other Ce-based catalysts documented in the literature, those of CeO2/Ti3C2-12 were respectively reduced by 83 °C and 38 °C, demonstrating a remarkable low-temperature activity advantage. Such a result is attributed to Ti3C2-induced CeO2 interface restructuring and lowered oxygen vacancies formation energy, which enhanced interfacial electron transfer thereby accelerated soot oxidation. This study proposes a facile and efficient CeO2 interface reconstruction strategy to develop superior catalysts for soot oxidation and contribute to meeting China National Emission Standard VI for diesel engines.