Oxygen vacancy promoted H2O activation over K+-doped ε-MnO2 for low-temperature HCHO oxidation

• Published in: Applied surface science Vol. 624; p. 157127
• Main Authors: Wang, Fanyu, Feng, Yaqin, Wang, Zhongsen, Liu, Yi, Gu, Huayu, Liu, Xiao
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.07.2023
• Subjects: K+-doped ε-MnO2; Low-Temperature HCHO Oxidation; Oxygen vacancy; Water activation; Low-Temperature HCHO Oxidation; Water activation; K+-doped ε-MnO2; Oxygen vacancy
• ISSN: 0169-4332; 1873-5584
• DOI: 10.1016/j.apsusc.2023.157127

Oxygen vacancy facilitates water activation to create reactive hydroxyl species for the improved low-temperature HCHO oxidation over K+-doped ε-MnO2. [Display omitted] •Surface oxygen vacancies were regulated with the aid of K doping over ε-MnO2.•Oxygen vacancies facilitated water activation to produce active hydroxyl species.•The active hydroxyl species and protonated lattice oxygen enhanced the catalytic oxidation activity of HCHO.•The optimized K+-doped ε-MnO2 exhibited the best catalytic performance for HCHO conversion with a T90 of 74 °C. H2O activation plays a crucial role in the oxidation process of HCHO, which can create active hydroxyl to attack HCHO molecules and enhance the catalytic activity. Therefore, the construction of highly active sites for H2O activation to accelerate the reaction rate is required. Herein, we constructed and regulated the surface oxygen vacancies over ε-MnO2 with the aid of K doping to activate H2O through a simple hydrothermal method. The role of oxygen vacancy produced by K+ doping for H2O activation in HCHO removal was investigated by various technologies, including XPS, TPD, TPSR, and in-situ DRIFTS. It was found that the addition of K+ not only increased the adsorption sites for negatively charged oxygen atoms of HCHO but also provided oxygen vacancies to induce more active hydroxyl species from water activation. The optimal K+-doped ε-MnO2 significantly removed 90% of HCHO at 74 °C (GHSV = 120 L/g·h, HCHO = 70 ppm). After the stability test at 65 and 80 °C for 100 h respectively, the conversion did not show a downward trend. This work innovatively developed a K-doped ε-MnO2 catalyst with surface oxygen vacancy to activate H2O and revealed the role of K+ and oxygen vacancy for efficient HCHO oxidation.