文献类型：期刊文献

英文题名：Effect of MnO2 Polymorphs? Structure on Low-Temperature Catalytic Oxidation: Crystalline Controlled Oxygen Vacancy Formation

作者：Tian, Fei-Xiang[1];Li, Hu[1];Zhu, Minghui[1];Tu, Weifeng[2];Lin, Dehai[2];Han, Yi-Fan[1,2]

机构：[1]East China Univ Sci & Technol, State Key Lab Chem Engn, Shanghai 200237, Peoples R China;[2]Zhengzhou Univ, Engn Res Ctr Adv Funct Mat Mfg, Minist Educ, Zhengzhou 450001, Peoples R China

年份：2022

卷号：14

期号：16

起止页码：18525

外文期刊名：ACS APPLIED MATERIALS & INTERFACES

收录：;EI(收录号：20221812046317);WOS:【SCI-EXPANDED(收录号:WOS:000812793000001)】；

基金：This work was funded by the National Natural Science Foundation of China (Grant no. 22078307) and the Program for Professor of Special Appointment (Eastern Scholar) at the Shanghai Institutions of Higher Learning and Shanghai Sailing Program (19YF1410600)

语种：英文

外文关键词：beta-MnO2; oxygen vacancy; low-temperature CO oxidation; kinetics; mechanism

摘要：MnO2 polymorphs (alpha-, beta-, and epsilon-MnO2) were synthesized, and their chemical/physical properties for CO oxidation were systematically studied using multiple techniques. Density functional theory (DFT) calculations and temperature-programmed experiments reveal that beta-MnO2 shows low energies for oxygen vacancy generation and excellent redox properties, exhibiting significant CO oxidation activity (T-90 = 75 degrees C) and stability even under a humid atmosphere. For the first time, we report that the specific reaction rate for beta-MnO2 (0.135 moleculeCO.nm(-2).s(-1) at 90 degrees C) is roughly approximately 4 and 17 times higher than that of epsilon-MnO2 and alpha-MnO2, respectively. The specific reaction rate order (beta-MnO2 > epsilon-MnO2 > alpha-MnO2) is not only in good agreement with reduction rates (CO-TPSR measurements) but also agrees with the DFT calculation. In combination with in situ spectra and intrinsic kinetic studies, the mechanisms of CO oxidation over various crystal structures of MnO2 were proposed as well. We believe the new insights from this study will largely inspire the design of such a kind of catalyst.