Manganese Oxide Nanoarray-Based Monolithic Catalysts: Tunable Morphology and High Efficiency for CO Oxidation

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• 作者：Sheng-Yu Chen ; Wenqiao Song ; Hui-Jan Lin ; Sibo Wang ; Sourav Biswas ; Mehdi Mollahosseini ; Chung-Hao Kuo ; Pu-Xian Gao ; Steven L. Suib
• 刊名：ACS Applied Materials & Interfaces
• 出版年：2016
• 出版时间：March 30, 2016
• 年：2016
• 卷：8
• 期：12
• 页码：7834-7842
• 全文大小：605K
• ISSN：1944-8252

文摘

A generic one-pot hydrothermal synthesis route has been successfully designed and utilized to in situ grow uniform manganese oxide nanorods and nanowires onto the cordierite honeycomb monolithic substrates, forming a series of nanoarray-based monolithic catalysts. During the synthesis process, three types of potassium salt oxidants have been used with different reduction potentials, i.e., K₂Cr₂O₇, KClO₃, and K₂S₂O₈, denoted as HM-DCM, HM-PCR, and HM-PSF, respectively. The different reduction potentials of the manganese source (Mn²⁺) and oxidants induced the formation of manganese oxide nanoarrays with different morphology, surface area, and reactivity of carbon monoxide (CO) oxidation. K₂Cr₂O₇ and KClO₃ can induce sharp and long nanowires with slow growth rates due to their low reduction potentials. In comparison, the nanoarrays of HM-PSF presented shorter nanorods but displayed an efficient 90% CO oxidation conversion at 200 °C (T90) without noble-metal loading. Reducibility tests for the three monolithic catalysts by hydrogen temperature-programmed reduction revealed an activation energy order of HM-PSF > HM-DCM > HM-PCR for CO oxidation. The characterizations of oxygen temperature-programmed desorption and X-ray photoelectron spectroscopy indicated the abundant surface-adsorbed oxygen and lattice oxygen contributing to the superior reactivity of HM-PSF. The straightforward synthetic process showed a scalable, low-cost, and template-free method to fabricate manganese oxide nanoarray monolithic catalysts for exhaust treatment.