Centre for Advanced Materials & Industrial Chemistry (CAMIC), School of Science, RMIT University , GPO BOX 2476, Melbourne, Victoria 3001, Australia.
Inorganic and Physical Chemistry Division, CSIR-Indian Institute of Chemical Technology , Uppal Road, Hyderabad 500 007, India.
ACS Appl Mater Interfaces. 2017 Sep 27;9(38):32652-32666. doi: 10.1021/acsami.7b07656. Epub 2017 Sep 12.
In the present work, nanowire morphologies of α-MnO, cobalt monodoped α-MnO, Cu and Co bidoped α-MnO, and Ni and Co bidoped α-MnO samples were prepared by a facile hydrothermal synthesis. The structural, morphological, surface, and redox properties of all the as-prepared samples were investigated by various characterization techniques, namely, scanning electron microscopy (SEM), transmission and high resolution electron microscopy (TEM and HR-TEM), powder X-ray diffraction (XRD), N sorption surface area measurements, X-ray photoelectron spectroscopy (XPS), hydrogen-temperature-programmed reduction (H-TPR), and oxygen-temperature-programmed desorption (O-TPD). The soot oxidation performance was found to be significantly improved via metal mono- and bidoping. In particular, Cu and Co bidoped α-MnO nanowires showed a remarkable improvement in soot oxidation performance, with its T (50% soot conversion) values of 279 and 431 °C under tight and loose contact conditions, respectively. The soot combustion activation energy for the Cu and Co bidoped MnO nanowires is 121 kJ/mol. The increased oxygen vacancies, greater number of active sites, facile redox behavior, and strong synergistic interaction were the key factors for the excellent catalytic activity. The longevity of Cu and Co bidoped α-MnO nanowires was analyzed, and it was found that the Cu/Co bidoped α-MnO nanowires were highly stable after five successive cycles and showed an insignificant decrease in soot oxidation activity. Furthermore, the HR-TEM analysis of a spent catalyst after five cycles indicated that the (310) crystal plane of α-MnO interacts with the soot particles; therefore, we can assume that more-reactive exposed surfaces positively affect the reaction of soot oxidation. Thus, the Cu and Co bidoped α-MnO nanowires provide promise as a highly effective alternative to precious metal based automotive catalysts.
在本工作中，通过简便的水热合成制备了 α-MnO、钴单掺杂 α-MnO、Cu 和 Co 共掺杂 α-MnO、Ni 和 Co 共掺杂 α-MnO 的纳米线形态。通过各种表征技术，即扫描电子显微镜（SEM）、透射电子显微镜（TEM）和高分辨率电子显微镜（HR-TEM）、粉末 X 射线衍射（XRD）、N 吸附比表面积测量、X 射线光电子能谱（XPS）、氢气程序升温还原（H-TPR）和氧气程序升温脱附（O-TPD），研究了所有制备样品的结构、形态、表面和氧化还原性质。通过金属单掺杂和共掺杂发现，烟尘氧化性能得到了显著提高。特别是，Cu 和 Co 共掺杂的 α-MnO 纳米线在烟尘氧化性能方面表现出显著的改善，在紧密和松散接触条件下，其 T（50%烟尘转化率）值分别为 279°C 和 431°C。Cu 和 Co 共掺杂 MnO 纳米线的烟尘燃烧活化能为 121 kJ/mol。增加的氧空位、更多的活性位、易还原的氧化还原行为和强协同相互作用是优异催化活性的关键因素。对 Cu 和 Co 共掺杂的 α-MnO 纳米线的长寿命进行了分析，发现 Cu/Co 共掺杂的 α-MnO 纳米线在经过五个连续循环后具有高度的稳定性，并且烟尘氧化活性没有明显下降。此外，五个循环后的失活催化剂的 HR-TEM 分析表明，α-MnO 的（310）晶面与烟尘颗粒相互作用；因此，我们可以假设更具反应性的暴露表面对烟尘氧化反应产生积极影响。因此，Cu 和 Co 共掺杂的 α-MnO 纳米线有望成为替代贵金属基汽车催化剂的高效替代品。
