Xing Gang, Liu Xuan, Jia Yazhen, Wu Jialin, Chai Liming, Zhai Wenjie, Wu Zhaojun, Kong Jing, Zhang Jianbin
Hebei Provincial Key Lab of Green Chemical Technology and High Efficient Energy Saving, School of Chemical Engineering and Technology, Hebei University of Technology, Tianjin 300130, China; Inner Mongolia Engineering Research Center for CO(2) Capture and Utilization, Inner Mongolia University of Technology, Hohhot 010051, China.
Environmental Engineering School of Energy and Power Engineering, Xi'an Jiaotong University, Xi'an 710049, China.
J Colloid Interface Sci. 2025 Jan;677(Pt B):417-428. doi: 10.1016/j.jcis.2024.08.085. Epub 2024 Aug 13.
Synthesis of catalysts with high catalytic degradation activity for formaldehyde (HCHO) at room temperature is highly desirable for indoor air quality control. Herein, a novel K-MnO@CeO catalyst with excellent catalytic oxidation activity toward HCHO at near room temperature was reported. In particular, the K addition in K-MnO@CeO considerably enhanced the oxidation activity, and importantly, 99.3 % conversion of 10 mL of a 40 mg/L HCHO solution at 30 °C for 14 h was achieved, with simultaneous strong cycling stability. Moreover, the addition of K species considerably influenced the chemical valence state of Mn from +4 (ε-MnO) to +8/3 (MnO) on the surface of CeO, which obviously changed the tunnel structure and the number of oxygen vacancies. One part of K species is uniformly dispersed on K-MnO@CeO, and the other part exists in the tunnel structure of MnO@CeO, which is mainly used to balance the negative charge of the tunnel and prevent collapse of the structure, providing enough active sites for the catalytic oxidation of HCHO. We observed a phase transition from tunneled KMnO to MnO to tunneled MnO with the decreasing K content, in which K-MnO@CeO exhibited higher HCHO oxidation activity. In addition, K-MnO@CeO exhibited lower oxygen vacancy formation and HCHO adsorption energies in aqueous solution based on density functional theory calculations. This is because the K species provide more active oxygen species and richer oxygen vacancies on the surface of K-MnO@CeO, promote the mobility of lattice oxygen and the room-temperature reduction properties of oxygen species, and enhance the ability of the catalyst to replenish the consumed oxygen species. Finally, a possible HCHO catalytic oxidation pathway on the surface of K-MnO@CeO catalyst is proposed.
合成具有高催化降解活性的室温甲醛（HCHO）催化剂对于室内空气质量控制非常必要。在此，报道了一种新型的K-MnO@CeO催化剂，其在近室温下对HCHO具有优异的催化氧化活性。特别是，K-MnO@CeO中K的加入显著提高了氧化活性，重要的是，在30℃下14小时内实现了10 mL 40 mg/L HCHO溶液99.3%的转化率，同时具有很强的循环稳定性。此外，K物种的加入显著影响了CeO表面Mn的化学价态，从+4（ε-MnO）变为+8/3（MnO），这明显改变了隧道结构和氧空位数量。一部分K物种均匀分散在K-MnO@CeO上，另一部分存在于MnO@CeO的隧道结构中，主要用于平衡隧道的负电荷并防止结构坍塌，为HCHO的催化氧化提供足够的活性位点。随着K含量的降低，我们观察到从隧道状KMnO到MnO再到隧道状MnO的相变，其中K-MnO@CeO表现出更高的HCHO氧化活性。此外，基于密度泛函理论计算，K-MnO@CeO在水溶液中表现出较低的氧空位形成能和HCHO吸附能。这是因为K物种在K-MnO@CeO表面提供了更多的活性氧物种和更丰富的氧空位，促进了晶格氧的迁移和氧物种的室温还原性能，并增强了催化剂补充消耗的氧物种的能力。最后，提出了K-MnO@CeO催化剂表面可能的HCHO催化氧化途径。
