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Song, Min-Kyu,Cheng, Shuang,Chen, Haiyan,Qin, Wentao,Nam, Kyung-Wan,Xu, Shucheng,Yang, Xiao-Qing,Bongiorno, Angelo,Lee, Jangsoo,Bai, Jianming,Tyson, Trevor A.,Cho, Jaephil,Liu, Meilin American Chemical Society 2012 Nano letters Vol.12 No.7
<P>While pseudocapacitors represent a promising option for electrical energy storage, the performance of the existing ones must be dramatically enhanced to meet today’s ever-increasing demands for many emerging applications. Here we report a nanostructured, mixed-valent manganese oxide film that exhibits anomalously high specific capacitance (∼2530 F/g of manganese oxide, measured at 0.61 A/g in a two-electrode configuration with loading of active materials ∼0.16 mg/cm<SUP>2</SUP>) while maintaining excellent power density and cycling life. The dramatic performance enhancement is attributed to its unique mixed-valence state with porous nanoarchitecture, which may facilitate rapid mass transport and enhance surface double-layer capacitance, while promoting facile redox reactions associated with charge storage by both Mn and O sites, as suggested by in situ X-ray absorption spectroscopy (XAS) and density functional theory calculations. The new charge storage mechanisms (in addition to redox reactions of cations) may offer critical insights to rational design of a new-generation energy storage devices.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/nalefd/2012/nalefd.2012.12.issue-7/nl300984y/production/images/medium/nl-2012-00984y_0006.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/nl300984y'>ACS Electronic Supporting Info</A></P>
Run Chen,Gang Li,Weiyang Bai,Shuang Bao,Zhiliang Cheng 성균관대학교(자연과학캠퍼스) 성균나노과학기술원 2018 NANO Vol.13 No.6
The development of highly active catalysts for the pyrolysis of ammonium perchlorate (AP) is of considerable importance for AP-based composite solid propellant. In the present study, we produced porous MgFe2O4 architectures by using a facile two-step strategy. A rod-like precursor of MgFe2(C2O4)3 · nH2O (diameter: 0.5–2.5 μm; length: 2–15 μm) was fabricated under solvothermal conditions using metal sulfates as raw materials and oxalic acid as the precipitant. Subsequently, porous MgFe2O4 architectures were obtained by the thermal treatment of the as-prepared oxalate precursor, during which the mesopores were formed in situ via the liberation of volatile gases, while the rod-like morphology was well preserved. The catalytic performances of the as-synthesized porous rod-like MgFe2O4 architectures with respect to the AP pyrolysis were assessed using differential scanning calorimetry (DSC) techniques. The results indicated that the high thermal decomposition temperature and the apparent activation energy of AP with 2 wt.% MgFe2O4 addition decreased from 445.4 ℃ to 386.7 ℃ and from 280.5ffi11.8 to 147.6ffi4.8 kJ mol-1, respectively. Meanwhile, the decomposition heat of AP with MgFe2O4 as the additive reached up to 1230.6 J g-1, which was considerably higher than that of its neat counterpart (695.8 J g-1). Thus, porous rod-like MgFe2O4 architectures could be served as the catalyst for the AP pyrolysis.