Chromium-doped cryptomelane: Mn-O debilitation and reactive enhancement in formaldehyde abatement

• Published in: Materials letters 2021-12, Vol.305, p.130777, Article 130777
• Main Authors: Tran-Thuy, Tuyet-Mai, Le, Thi-Phuong, Tran, Trong-Phu, Lam, Hoa-Hung, Nguyen, Long Q., Nguyen, Dung V., Dang-Bao, Trung
• Format: Article
• Language: English
• Subjects: AOS of manganese; Atomic oxygen; Chromium; Cr-doped cryptomelane; Debilitation of Mn-O in Mn-O-Cr bridges; Desorption; Distortion of (exotic metal) bridges; Formaldehyde; Formaldehyde abatement; Materials science; Nanorods; Oxidation
• ISSN: 0167-577X; 1873-4979
• DOI: 10.1016/j.matlet.2021.130777

•Nano-rod chromium-doped cryptomelane was synthesized by co-precipitation.•Effect of chromium-doped amount on average oxidation state of manganese.•Formaldehyde abatement: contributions of chromium-doping weakening Mn-O bonds in Mn-O-Cr bridges. Nano-rod chromium-doped cryptomelane was prepared by co-precipitation and characterized by XRD, EDX elemental maps, SEM, ICP-MS and N2 adsorption. Temperature-programmed desorption of oxygen (O2-TPD) revealed a significant down-shift of oxygen desorption temperature regarding atomic oxygen bounded Mn3+ sites from ~40 to ~488 °C corresponded to 0–4.9 wt% of chromium loading. This result was consistent with the elevation of Mn-average-oxidation-state (Mn-AOS) from 3.6 to 3.8 for non-doped and Cr-doped cryptomelane samples. The catalytic performance of Cr-doped cryptomelane on formaldehyde oxidation was correlated with the chromium loading because of the change in Mn-AOS values and debilitation of Mn-O in Mn-O-Cr bridges.